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%%% ==================================================================== %%% BibTeX-file{ %%% filename = "iandc.bib", %%% version = "3.15a", %%% url = "http://theory.lcs.mit.edu/~iandc/iandc.bib", %%% date = "02 July 1999", %%% time = "17:19:33 EDT", %%% author = "David M. Jones", %%% address = "MIT Laboratory for Computer Science %%% Room NE43-316 %%% 545 Technology Square %%% Cambridge, MA 02139 %%% USA", %%% telephone = "(617) 253-5936", %%% FAX = "(617) 253-3480", %%% checksum = "56693 25180 107300 928526", %%% email = "iandc at theory.lcs.mit.edu", %%% codetable = "ISO/ASCII", %%% keywords = "theoretical computer science, bibliography, %%% BibTeX", %%% supported = "yes", %%% docstring = "This is a BibTeX bibliography for the %%% journal {\em Information and Computation}, %%% published by Academic Press. It covers the %%% years 1982 through the present (volumes 52 %%% through the present) and is updated %%% monthly. A list of forthcoming papers can %%% be found at the end of this file, under the %%% headings "FORTHCOMING" and "FUTURE %%% ATTRACTIONS". %%% %%% A companion bibliography containing papers %%% published before 1982 is also available: %%% %%% ftp://theory.lcs.mit.edu/pub/iandc/ic.bib %%% %%% This bibliography is also available as a %%% World Wide Web hyptertext document via the %%% following URL: %%% %%% http://theory.lcs.mit.edu/~iandc/ %%% %%% Abstracts for recent papers are available in %%% the WWW version. %%% %%% The checksum field above contains a CRC-16 %%% checksum as the first value, followed by the %%% equivalent of the standard UNIX wc (word %%% count) utility output of lines, words, and %%% characters. This is produced by Robert %%% Solovay's checksum utility.", %%% } %%% ==================================================================== INFORMATION AND COMPUTATION January 1982 -- present Volumes 52--current Albert R. Meyer, Editor-in-Chief This is BibTeX bibliography containing all papers published in Information and Computation since January 1982. There are undoubtably numerous small errors left in it. Please report any errors you find to iandc at theory.lcs.mit.edu. For documentation on using this file, see Chapter 13 of "The LaTeX Companion" by Michel Goossens and Frank Mittelbach and Alexander Samarin, Addison-Wesley, 1993, or Section 4.3 and Appendix B of "LaTeX: A Document Preparation System" by Leslie Lamport. NOTE: This file will only work under BibTeX version 0.99a or later, as it makes use of the string concatenation feature which was introduced in that release. This file is updated on a monthly basis. For information on ordering back issues, write to Academic Press, Inc. Journal Division/Back Volumes Suite 1900 525 B Street San Diego, CA 92101-4495 Attn: Stephanie Burton The name of the journal was originally "Information and Control." It was changed in January 1987 to "Information and Computation." For convenience, we use the following two strings for the journal titles. @string{iandc={Information and Control}} @string{iandcomp={Information and Computation}} INFORMATION AND CONTROL January 1982 Volume 52, Number 1 Special Issue NSF Workshop on Recursion Theoretic Aspects of Computer Science Martin Davis, Carl Smith and Paul Young -- Special Issue Editors @Article{DavisSY82a, title={Introduction}, author={Martin Davis and Carl Smith and Paul Young}, pages={1}, journal=iandc, month=jan, year=1982, volume=52, number=1 } @Article{Hay82, title={On the Recursion-Theoretic Complexity of Relative Succinctness of Representations of Languages}, author={Louise Hay}, pages={2--7}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={sicomp::Hartmanis1980, focs::MeyerF1971:188, sicomp::SchmidtS1977, ic::Valiant1976} } @Article{Soare82, title={Computational Complexity of Recursively Enumerable Sets}, author={Robert I. Soare}, pages={8--18}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={tcs::BennisonS1978, jacm::Blum1967, jacm::Blum1971} } @Article{MenzelS82, title={Universal Automata with Uniform Bounds on Simulation Time}, author={W. Menzel and V. Sperschneider}, pages={19--35}, journal=iandc, month=jan, year=1982, volume=52, number=1 } @Article{Selman82, title={Analogues of Semicursive Sets and Effective Reducibilities to the Study of {{\em NP\/}} Complexity}, author={Alan L. Selman}, pages={36--51}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={sicomp::BakerGS1975, ic::Book1974, jcss::Book1974, jcss::Breidbart1978, stoc::Cook1971, stoc::KarpL1980, mst::Ko1983, jcss::Ko1982, jacm::Ladner1975, tcs::LadnerLS1975, tcs::Long1982, mst::Selman1979, tcs::Selman1982, jcss::Selman1981, tcs::Stockmeyer1976, tcs::Wrathall1976} } @Article{Daley82, title={Busy Beaver Sets: Characterizations and Applications}, author={Robert P. Daley}, pages={52--67}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={jacm::Blum1967, ic::Blum1967, mfcs::Daley1979} } @Article{Chen82, title={Tradeoffs in the Inductive Inference of Nearly Minimal Size Programs}, author={Keh-Jiann Chen}, pages={68--86}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={jacm::Blum1967, ic::Blum1967, ic::BlumB1975, ic::Case1983:100, stoc::CaseS1978, ic::Gold1967, ic::Meyer1972, ic::Schubert1974} } @Article{Meyer82, title={What is a Model of the Lambda Calculus?}, author={Albert R. Meyer}, pages={87--122}, journal=iandc, month=jan, year=1982, volume=52, number=1, references={tcs::Plotkin1975, tcs::Plotkin1977, jcss::Plotkin1978, sicomp::Scott1976, sicomp::Wadsworth1976}, abstract={An elementary, purely algebraic definition of model for the untyped lambda calculus is given. This definition is shown to be equivalent to the natural semantic definition based on environments. These definitions of model are consistent with, and yield a completeness theorem for, the standard axioms for lambda convertibility. A simple construction of models for lambda calculus is reviewed. The algebraic formulation clarifies the relation between combinators and lambda terms.} } February 1982 Volume 52, Number 2 @Article{OshersonW82, title={Criteria of Language Learning}, author={Daniel N. Osherson and Scott Weinstein}, pages={123--138}, journal=iandc, month=feb, year=1982, volume=52, number=2, references={ic::BlumB1975, ic::Feldman1972, ic::Gold1967, ic::Wharton1974} } @Article{ArbibM82, title={Parametrized Data Types Do Not Need Highly Constrained Parameters}, author={Michael A. Arbib and Ernest G. Manes}, pages={139--158}, journal=iandc, month=feb, year=1982, volume=52, number=2, references={jcss::AdamekK1979, mst::LehmannS1981:97, toplas::ThatcherWW1982:711} } @Article{BergstraCT82, title={Another Incompleteness Result for {Hoare's} Logic}, author={Jan Bergstra and Anna Chmielinska and Jerzy Tiuryn}, pages={159--171}, journal=iandc, month=feb, year=1982, volume=52, number=2, references={tcs::BergstraT1982, jcss::BergstraT1982, sicomp::Cook1978, ipl::BergstraT1982, stoc::HarelMP1977, jacm::Wand1978} } @Article{AlbertCK82, title={Test Sets for Context Free Languages and Algebraic Systems of Equations over a Free Monoid}, author={J. Albert and K. {Culik II} and J. Karhum{\"a}ki}, pages={172--186}, journal=iandc, month=feb, year=1982, volume=52, number=2, references={ic::AlbertC1980, jcss::CulikS1978, jcss::CulikS1980} } @Article{Tomita82, title={A Direct Branching Algorithm for Checking Equivalence of Some Classes of Deterministic Pushdown Automata}, author={Etsuji Tomita}, pages={187--238}, journal=iandc, month=feb, year=1982, volume=52, number=2, references={tcs::Beeri1976, tcs::Courcelle1978, jcss::FriedmanG1979, sicomp::HarrisonH1972, tcs::HarrisonHY1979, focs::KorenjakH1966, jcss::Linna1979, tcs::OlshanskyP1977, ic::OyamaguchiH1978, ic::OyamaguchiH1980:90, ic::RosenkrantzS1970, jcss::TaniguchiK1976, tcs::Tomita1983, ic::Valiant1974, jcss::Valiant1975} } March 1982 Volume 52, Number 3 @Article{BorodinGH82, oldkey={GathenBH82}, title={Fast Parallel Matrix and {GCD} Computations}, author={Allan Borodin and Joachim von zur Gathen and John Hopcroft}, pages={241--256}, journal=iandc, month=mar, year=1982, volume=52, number=3, references={tcs::BaurS1983, sicomp::Csanky1976, stoc::FortuneW1978, stoc::Gathen1983, tcs::GoldschlagerSS1982, focs::Pippenger1979, sicomp::Rabin1980, sicomp::ValiantSBR1983:641} } @Article{DolevFFLS82, oldkey={StrongDFF82}, title={An Efficient Algorithm for {Byzantine} Agreement without Authentication}, author={Danny Dolev and Michael J. Fischer and Rob Fowler and Nancy A. Lynch and H. Raymond Strong}, pages={257--274}, journal=iandc, month=mar, year=1982, volume=52, number=3, abstract={Byzantine Agreement involves a system of $n$ processes, of which some $t$ may be faulty. The problem is for the correct processes to agree on a binary value sent by a transmitter that may itself be one of the $n$ processes. If the transmitter sends the same value to each process, then all correct processes must agree on that value, but in any case, they must agree on some value. An explicit solution not using authentication for $n=3t+1$ processes is given, using $2t+3$ rounds and $O(t^3 \log t)$ message bits. This solution is easily extended to the general case of $n \geq 3t+1$ to give a solution using $2t+3$ rounds and $O(nt + t^3 \log t)$ message bits.}, references={stoc::DeMilloLM1982, jalgo::Dolev1982, focs::Dolev1981, stoc::DolevS1982, toplas::Lamport1984:254, toplas::LamportSP1982, jacm::PeaseSL1980} } @Article{CourcelleF82, title={On the Equivalence Problem for Attribute Systems}, author={Bruno Courcelle and Paul Franchi-Zannettacci}, pages={275--305}, journal=iandc, month=mar, year=1982, volume=52, number=3, references={mst::ChiricaM1979, tcs::Courcelle1978, mst::Courcelle1983, tcs::CourcelleF1982, jcss::CourcelleV1976, jacm::Huet1980, mst::Knuth1968, toplas::MartelliM1982, sicomp::Mayoh1981, ic::Valiant1974} } @Article{Koymans82, title={Models of the Lambda Calculus}, author={C. P. J. Koymans}, pages={306--332}, journal=iandc, month=mar, year=1982, volume=52, number=3, references={sicomp::Scott1976} } @Article{ButzerE82a, title={Dyadic Calculus and Sampling Theorems for Functions with Multidimensional Domain. {I}: General Theory}, author={P. L. Butzer and W. Engels}, pages={333--351}, journal=iandc, month=mar, year=1982, volume=52, number=3 } @Article{ButzerE82b, title={Dyadic Calculus and Sampling Theorems for Functions with Multidimensional Domain. {II}: Applications to Dyadic Sampling Representations}, author={P. L. Butzer and W. Engels}, pages={352--363}, journal=iandc, month=mar, year=1982, volume=52, number=3, references={ic::PetersenM1962, ic::ButzerS1977} } @Article{KleijnR82, title={Corrigendum: Sequential, Continuous and Parallel Grammars}, author={H. C. M. Kleijn and G. Rozenberg}, pages={364}, journal=iandc, month=mar, year=1982, volume=52, number=3, references={KleijnR1981:221} } Author Index for Volume 52 -- page 367 April/May 1982 Volume 53, Numbers 1/2 @Article{Paul82, title={On-Line Simulation of $k+1$ Tapes by $k$ Tapes Requires Nonlinear Time}, author={W. Paul}, pages={1--8}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={jacm::HennieS1966, focs::Paul1981, jcss::PaulSS1981} } @Article{NathK82, title={On Some Characterizations of the Shannon Entropy Using Extreme Symmetry and Block Symmetry}, author={Prem Nath and Man Mohan Kaur}, pages={9--20}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2} } @Article{Ko82, title={Some Negative Results on the Computational Complexity of Total Variation and Differentiation}, author={Ker-I Ko}, pages={21--31}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={jcss::Ko1982, tcs::KoF1982} } @Article{OshersonSW82, title={Learning Strategies}, author={Daniel N. Osherson and Michael Stob and Scott Weinstein}, pages={32--51}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={ic::Angluin1980, ic::BlumB1975, ic::Gold1967, ic::OshersonW1982} } @Article{Sippu82, title={Derivational Complexity of Context-Free Grammars}, author={Seppo Sippu}, pages={52--65}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={sicomp::AhoU1973, jcss::Book1971, tcs::Heilbrunner1981, actai::Pager1977} } @Article{Borden82, title={Optimal Asymmetric Error Detecting Codes}, author={J. Martin Borden}, pages={66--73}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={ic::Berger1961, ic::ConstantinR1979, ic::Freiman1962} } @Article{Kantor82, title={An Exponential Number of Generalized Kerdock Codes}, author={William M. Kantor}, pages={74--80}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={Kerdock1972} } @Article{Minamide82, title={An Extension of the Entropy Theorem for Parameter Estimation}, author={Nariyasu Minamide}, pages={81--90}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={ic::WeidemannS1969} } @Article{Sifakis82, title={Global and Local Invariants in Transition Systems}, author={Joseph Sifakis}, pages={91--107}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, abstract={Given a transition system and a cover $P$ of the set of its states, a set of local invariants with respect to $P$ is defined as a set of predicates in bijection with the set of the blocks of $P$ in such a way that a local invariant is true every time the system is in a state belonging to teh corresponding block of the cover. This definition is proved to be sufficiently general in the sense that any proof made by using global invariants can be also made by using sets of local invariants with respect to any cover $P$. The same result is proved for for two more restrictive definitions of the notion of local invariant by using well-known properties of connections between lattices. Finally, it is shown that the notion of invariant assertion, commonly used for proving programs can be deduced from the definition of local invariant when a transition system represents a program. In this case, the fixed point equations characterizing local invariants can be simplified to obtain semantical equations of programs.}, references={jcss::Ashcroft1975, TR::Birkle1973, IWPC::CousotC1980, PSAM::Floyd1967:19, TR::Keller1972, CACM::Keller1976, POPL::Lamport1980, CACM::MannaW1978, ISSTFPM::MannaP1981, ALGOR2::Mazurkiewicz1974, LNCS::Pnueli1979, TAMS::Ore1944:493, RAIRO::Sanchis1977:339, ISP::QueilleS1982, TCS::Sifakis1982} } @Article{ReedR82, title={Recognition of Surfaces in Three-Dimensional Digital Images}, author={George M. Reed and Azriel Rosenfield}, pages={108--120}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={ic::Rosenfeld1981, ic::MorgenthalerR1981} } @Article{GolzeP82, title={Petri Net Implementations by a Universal Cell Space}, author={Ulrich Golze and Lutz Priese}, pages={121--138}, journal=iandc, month=apr # "/" # may, year=1982, volume=53, number={1/2}, references={jcss::Golze1978, tcs::Kwong1977, jcss::LiptonMS1977, ic::MaruokaK1977, jcss::Priese1978, tcs::Priese1983, jcss::Richardson1972, jacm::Smith1971:339, ic::Smith1971, jcss::Yaku1976, ic::YamadaA1971} } June 1982 Volume 53, Number 3 @Article{SippuS82, title={On {LL}($k$) Parsing}, author={Seppo Sippu and Eljas Soisalon-Soininen}, pages={141--164}, journal=iandc, month=jun, year=1982, volume=53, number=3, references={actai::FischerMQ1980, jcss::GellerH1977, ic::Knuth1965, actai::Knuth1971, jacm::LewisS1968, ic::RosenkrantzS1970} } @Article{LehmannS82, title={Reasoning with Time and Chance}, author={Daniel Lehmann and Saharon Shelah}, pages={165--198}, journal=iandc, month=jun, year=1982, volume=53, number=3, references={popl::Ben-AriMP1981, stoc::EmersonH1982, stoc::FeldmanH1982, popl::GabbayPSS1980, stoc::HalpernR1983, popl::HartSP1982, jcss::Kozen1981, popl::Lamport1980, sicomp::Lehmann1982, popl::LehmannR1981, tcs::Pnueli1981, jcss::Rabin1982, actai::Rabin1982, stoc::Reif1980, stoc::SistlaC1982:159, sicomp::SolovayS1977} } @Article{Hashiguchi82, title={Regular Languages of Star Height One}, author={K. Hashiguchi}, pages={199--210}, journal=iandc, month=jun, year=1982, volume=53, number=3, references={jcss::Cohen1970, jcss::CohenB1970, ic::DejeanS1966, jcss::Hashiguchi1982, jcss::Hashiguchi1983, ic::HashiguchiH1976, ic::HashiguchiH1979, ic::McNaughton1967} } @Article{PapadimitriouT82, title={On the Complexity of Designing Distributed Protocols}, author={Christos H. Papadimitriou and John Tsitsiklis}, pages={211--218}, journal=iandc, month=jun, year=1982, volume=53, number=3, references={focs::Abelson1978, stoc::Cook1971, focs::KanellakisP1981, stoc::Ladner1979, stoc::LiptonS1981, stoc::PapadimitriouS1982, stoc::Schaefer1978:216, stoc::Yao1979} } Author Index for Volume 53 -- page 219 July/August 1982 Volume 54, Numbers 1/2 Special Issue NSF Workshop on Recursion Theoretic Aspects of Computer Science Martin Davis, Carl Smith and Paul Young -- Special Issue Editors @Article{DavisSY82b, title={Introduction}, author={Martin Davis and Carl Smith and Paul Young}, pages={1}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2} } @Article{Davis82, title={Why {G{\"o}del} Didn't Have {Church's} Thesis}, author={Martin Davis}, pages={3--24}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2} } @Article{Blair82, title={The Recursion-Theoretical Complexity of the Semantics of Predicate Logic as a Programming Language}, author={Howard A. Blair}, pages={25--47}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2}, references={jacm::Robinson1965, jacm::EmdenK1976} } @Article{MandersD82, title={The Complexity of the Validity Problem for Dynamic Logic}, author={Kenneth L. Manders and Robert R. Daley}, pages={48--69}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2}, references={mfcs::AndrekaNS1979, stoc::HarelMP1977, jcss::MeyerP1981} } @Article{BakkerZ82, title={Processes and the Denotational Semantics of Concurrency}, author={J. W. de Bakker and J. I. Zucker}, pages={70--120}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2}, references={toplas::AptFR1980, tcs::ArnoldN1980, mfcs::Bakker1977, stoc::BakkerZ1982, tcs::Boussinot1982, jcss::FrancezHLR1979, focs::FrancezLP1980, mfcs::HennessyP1979, popl::Kosinski1978:214, focs::Lehmann1976, jacm::MilneM1979, jacm::Milner1979, sicomp::Plotkin1976, focs::Pnueli1977, popl::Pratt1982, focs::RoundsB1981, sicomp::Scott1976, jcss::Smyth1978, tcs::Wadge1981} } @Article{Streett82, title={Propositional Dynamic Logic of Looping and Converse Is Elementarily Decidable}, author={Robert S. Streett}, pages={121--141}, journal=iandc, month=jul # "/" # aug, year=1982, volume=54, number={1/2}, references={popl::Ben-AriMP1981, jcss::FischerL1979, focs::HossleyR1972, ic::McNaughton1966, stoc::Mirkowska1980, mfcs::Parikh1978, focs::Parikh1978, tcs::Park1976, focs::Pratt1976, focs::Pratt1979, focs::Pratt1981:421, stoc::Streett1981} } September 1982 Volume 54, Number 3 @Article{Zachos82, title={Robustness of Probabilistic Computational Complexity Classes under Definitional Perturbations}, author={Stathis Zachos}, pages={143--154}, journal=iandc, month=sep, year=1982, volume=54, number=3, references={stoc::AdlemanM1977, focs::Adleman1978, tcs::Angluin1980, sicomp::BennettG1981:96, sicomp::Gill1977, jacm::Rackoff1982, sicomp::SolovayS1977} } @Article{MaurerRW82, title={Using String Languages to Describe Picture Languages}, author={H. A. Maurer and G. Rozenberg and E. Welzl}, pages={155--185}, journal=iandc, month=sep, year=1982, volume=54, number=3, references={ic::Feder1968, acmcs::Freeman1974, ic::Shaw1969} } @Article{BergstraT82, title={The Completeness of the Algebraic Specification Methods for Computable Data Types}, author={J. A. Bergstra and J. V. Tucker}, pages={186--200}, journal=iandc, month=sep, year=1982, volume=54, number=3, references={Sicomp::BergstraT1983, actai::GuttagH1978, ieeetse::LiskovZ1975, jcss::Wand1979, mfcs::WirsingB1980, mfcs::GiarratanaGM1976} } @Article{Rocca82, title={Characterization Theorems for a Filter Lambda Model}, author={Ronchi Della Rocca, Simonetta}, pages={201--216}, journal=iandc, month=sep, year=1982, volume=54, number=3, references={jcss::Plotkin1978, TCS::RoccaV1984} } @Article{GalilD82, title={On Reversal-Bounded Counter Machines and on Pushdown Automata with a Bound on the Size of their Pushdown Store}, author={Pavol Duris and Zvi Galil}, pages={217--227}, journal=iandc, month=sep, year=1982, volume=54, number=3, references={stoc::Chan1981, tcs::DurisG1982, jcss::FreedmanL1975, mst::Galil1977} } Author Index for Volume 54 -- page 228 October/November/December 1982 Volume 55, Numbers 1-3 @Article{RivestS82, title={How to Reuse a ``Write-Once'' Memory}, author={Ronald L. Rivest and Adi Shamir}, pages={1--19}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, preliminary={STOC::RivestS1982} } @Article{Vitanyi82, title={On Efficient Simulations of Multicounter Machines}, author={Paul M. B. Vit{\'a}nyi}, pages={20--39}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, abstract={An oblivious 1-tape Turing machine can simulate a multicounter machine on-line in linear time and logarithmic space. This leads to a linear cost combinational logic network implementing the first $n$ steps of a multicounter machine and also to a linear time/logarithmic space on-line simulation by an oblivious logarithmic cost RAM\@. An oblivious $\log *n$-head tape unit can simulate the first $n$ steps of a multicounter machine in real-time, which leads to a linear cost combinational logic network with a constant data rate.}, references={MST::FischerR1968, MST::FischerMR1968, TAMS::HartmanisS1965, ANNMA::Minsky1961, BOOK::MeadC1980, MISC::PatersonFM1974, JACM::PippengerF1979, JACM::Rosenberg1967, ACTAI::Schnorr1976, STOC::Vitanyi1982} } @Article{Kannan82, title={Circuit-Size Lower Bounds and Non-Reducibility to Sparse Sets}, author={R. Kannan}, pages={40--56}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, preliminary={FOCS::Kannan1981}, references={focs::Adleman1978, sicomp::BermanH1977, focs::Blum1981, jcss::BookGW1970, sicomp::Borodin1977, jacm::ChandraKS1981, stoc::Cook1971, stoc::GoldwasserM1982, focs::Immerman1980, stoc::KarpL1980, focs::LamagnaS1974, focs::Mahaney1980, focs::MeyerS1972, tcs::Paterson1975, stoc::Paul1975, tcs::Pippenger1980, jacm::PippengerV1976, sicomp::Pratt1975, focs::Ruzzo1979, jacm::Savage1972, mst::Stockmeyer1977, tcs::Wegener1979, focs::Yao1982} } @Article{DolevEK82, title={On the Security of Ping-Pong Protocols}, author={D. Dolev and S. Even and R. M. Karp}, pages={57--68}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={jacm::Rosen1973} } @Article{GurevichL82, title={The Inference Problem for Template Dependencies}, author={Yuri Gurevich and Harry R. Lewis}, pages={69--79}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, abstract={Answering a question of Jeffrey Ullman, the problem in the title is shown to be undecidable.}, preliminary={PODS::GurevichL1982}, references={stoc::ChandraLM1981, stoc::Fagin1980, sicomp::FaginMUY1983:36, stoc::SadriU1980, jacm::SadriU1982, pods::Vardi1982:230, focs::YannakakisP1980} } @Article{BlassG82, title={On the Unique Satisfiability Problem}, author={Andreas Blass and Yuri Gurevich}, pages={80--88}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, abstract={Papadimitriou and Yannakakis were interested whether Unique Sat is hard for $\{\, L-L' : L, L' \mbox{ are NP}\,\}$ when NP $\neq$ co-NP (otherwise the answer is obvious). We show that this is true under one oracle and false under another.}, references={sicomp::BakerGS1975, stoc::PapadimitriouY1982} } @Article{BerklingF82, title={A Consistent Extension of the Lambda-Calculus as a Base for Functional Programming Languages}, author={Klaus J. Berkling and Elfriede Fehr}, pages={89--101}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={tcs::Plotkin1977, sicomp::Scott1976, spe::Turner1979} } @Article{Simon82, title={A Tight {$\Omega(\log\log n)$}-Bound on the Time for Parallel {RAM}'s to Compute Nondegenerated {Boolean} Functions}, author={Hans-Ulrich Simon}, pages={102--106}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={stoc::BorodinH1982, stoc::CookD1982} } @Article{ZaksFPM82, title={Fair Deriviations in Context-Free Grammars}, author={Sara Porat and Nissim Francez and Shlomo Moran and Shmuel Zaks}, pages={108--116}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={tcs::Dershowitz1982, jcss::GinsburgS1968, ic::Yntema1967} } @Article{EvenLY82, title={A Note on Deterministic and Nondeterministic Time Complexity}, author={Shimon Even and Timothy J. Long and Yacov Yacobi}, pages={117--124}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={jcss::ChewM1981, jacm::Ladner1975, tcs::LandweberLR1981, tcs::Schoning1982, tcs::Stockmeyer1976, tcs::Wrathall1976} } @Article{WoodEZM82, title={The Theory of Fringe Analysis and Its Application to 2-3 Trees and {B}-Trees}, author={Bernhard Eisenbarth and Nivio Ziviani and Gaston H. Gonnet and Kurt Mehlhorn and Derick Wood}, pages={125--174}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={actai::BayerM1972, actai::BayerS1977, ipl::Brown1979, acmcs::Comer1979:121, acmcs::Comer1979:412, actai::HuddlestonM1982, sicomp::Mehlhorn1982, actai::Yao1978} } @Article{HarelS82, title={Looping vs. Repeating in Dynamic Logic}, author={D. Harel and R. Sherman}, pages={175--192}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, abstract={Two extensions of propositional dynamic logic for dealing with infinite computations, LPDL and RPDL, are compared in expressive power. The first is obtained by adding the assertion {\em loop\/}($a$) for any program $a$, meaning ``$a$ contains an infinite computation,'' and the second by adding {\em repeat\/}($a$), meaning ``$a$ can be repeated indefinitely.'' While {\em repeat\/} can be used to encode {\em loop}, and hence LPDL$\leq$RPDL, it is shown here that the converse fails. Thus LPDL$<$RPDL. The proof is surprisingly nontrivial, especially in the presence of tests. The significance of the result is discussed and is put in perspective with other known results for LPDL, RPDL and their first-order counterparts. Some open questions are posed.}, references={stoc::EmersonH1982, jcss::FischerL1979, popl::HarelP1978, tcs::MeyerW1982, ic::McNaughton1966, focs::Pratt1976, ic::Streett1982} } @Article{ItoITT82, title={Two-Dimensional Alternating {Turing} Machines with Only Universal States}, author={Akira Ito and Katsushi Inoue and Itsuo Takanami and Hiroshi Taniguchi}, pages={193--221}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={focs::BlumH1967, jacm::ChandraKS1981, mst::GurariI1982, jacm::HopcroftU1969:168, stoc::InoueTT1982, tcs::InoueTT1983, stoc::King1981, focs::LadnerLS1978, actai::PaulPR1980, actai::PaulR1980, jcss::Ruzzo1980, focs::Sudborough1980} } @Article{Blake82, title={The Enumeration of Certain Run-Length Sequences}, author={Ian F. Blake}, pages={222--236}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3}, references={ic::Franaszek1969, ic::FreimanW1964, ic::TangB1970} } @Article{NeuhoffS82, title={Channel Distances and Representation}, author={D. L. Neuhoff and P. C. Shields}, pages={238--264}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1982, volume=55, number={1--3} } Author Index for Volume 55 -- pages 265-266 Cumulative Subject Index for Volumes 52-55 -- pages 267-275 January/February 1983 Volume 56, Numbers 1/2 @Article{Miller83a, title={Isomorphism of $k$-Contractible Graphs. {A} Generalization of Bounded Valence and Bounded Genus}, author={Gary L. Miller}, pages={1--20}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={STOC::FilottiM1980, STOC::Hoffmann1980, STOC::Lichtenstein1980, FOCS::Luks1980, STOC::Miller1980, STOC::BabaiGM1982, sicomp::BabaiES1980, jcss::Miller1979, sicomp::Valiant1979, sicomp::HopcroftT1973, tcs::Angluin1980, ipl::Mathon1979} } @Article{Miller83b, title={Isomorphism of Graphs Which are Pairwise $k$-separable}, author={Gary L. Miller}, pages={21--33}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={STOC::FilottiM1980, STOC::Hoffmann1980, STOC::Lichtenstein1980, FOCS::Luks1980, STOC::Miller1980, STOC::BabaiGM1982, sicomp::BabaiES1980, jcss::Miller1979, sicomp::Valiant1979, sicomp::HopcroftT1973, tcs::Angluin1980, ipl::Mathon1979} } @Article{BraunmuhlCMV83, refkey={BraunmuhlCV83}, title={The Recognition of Deterministic {CFL}'s in Small Time and Space}, author={Burchard von Braunm{\"u}hl and Stephen Cook and Kurt Mehlhorn and Rutger Verbeek}, pages={34--51}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={FOCS::BraunmuhlV1980, FOCS::Cobham1966, STOC::Cook1979, FOCS::DymondC1980, FOCS::Hong1980, FOCS::LewisSH1965, FOCS::Pippenger1979:307, FOCS::Ruzzo1979, JACM::Sudborough1978, FOCS::Sudborough1980, FOCS::Verbeek1981} } @Article{DavisW83, title={A Formal Notion of Program-Based Test Data Adequacy}, author={Martin D. Davis and Elaine J. Weyuker}, pages={52--71}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={ieeetse::Howden1982, ieeetse::McCabe1976, ieeetse::WeyukerO1980, ieeetse::WhiteC1980, ieeetse::WoodwardHH1979, actai::Howden1978} } @Article{Wolper83, title={Temporal Logic Can Be More Expressive}, author={Pierre Wolper}, pages={72--99}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={FOCS::HarelKP1980, FOCS::HarelPS1981, FOCS::HalpernR1981, FOCS::Pnueli1977, STOC::SistlaC1982, STOC::Streett1981, popl::Ben-AriMP1981, jcss::CohenG1977, jcss::FischerL1979, popl::GabbayPSS1980, tcs::KozenP1981, jcss::Savitch1970, popl::Wolper1982, icalp::EmersonC1980} } @Article{Case83, title={Pseudo-Extending Computable Functions}, author={John Case}, pages={100--111}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, references={JACM::Blum1967, JACM::Blum1971, jsyml::MollM1974, jsyml::Rogers1958} } @Article{MeyerM83, title={Termination Assertions for Recursive Programs: Completeness and Axiomatic Definability}, author={Albert R. Meyer and John C. Mitchell}, pages={112--138}, journal=iandc, month=jan # "/" # feb, year=1983, volume=56, number={1/2}, abstract={The termination assertion $p\langle S\rangle q$ means that whenever the formula~$p$ is true, there is an execution of the possibly nondeterministic program~$S$ which terminates in a state in which $q$ is true. The program~$S$ may declare and use local variables and nondeterministic procedures with call-by-value and call-by-address parameters. In addition, the program may call undeclared global procedures. Formulas $p$ and~$q$ are first-order formulas extended to express hypotheses about the termination of calls to undeclared procedures. A complete effective axiom system with rules corresponding to the syntax of the programming language is given for the termination assertions valid over all interpretations. Termination assertions define the semantics of programs in the following sense: if two programs have different input-output semantics, then there is a termination assertion that is valid for one program but not the other. Thus the complete axiomatization of termination assertions is an axiomatic definition of the semantics of recursive programs.}, references={JACM::Clarke1979, STOC::HarelMP1977, JACM::MeyerH1982, FOCS::Pratt1976, toplas::Apt1981, popl::CartwrightM1979, sicomp::Cook1978, tcs::Csirmaz1981, tcs::Gallier1981, jcss::LuckhamPP1970} } March 1983 Volume 56, Number 3 @Article{CulikS83, title={Ambiguity and Decision Problems Concerning Number Systems}, author={Karel {Culik II} and Arto Salomaa}, pages={139--153}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={tcs::MaurerSW1983:331} } @Article{Mitchell83, title={The Implication Problem for Functional and Inclusion Dependencies}, author={John C. Mitchell}, pages={154--173}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={acmtds::BeeriB1979, sigmod::BeeriFH1977, pods::BeeriK1982:55, pods::CasanovaFP1982, jcss::CasanovaFP1984:29, acmtds::Chen1976, acmtds::Codd1979:397, acmtds::Fagin1981, pods::JohnsonK1982, stoc::KanellakisCV1983, pods::Mitchell1983, jcss::YannakakisP1982, jsyml::Post1947} } @Article{VishkinW83, title={Dynamic Parallel Memories}, author={Uzi Vishkin and Avi Wigderson}, pages={174--182}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={sicomp::GabowK1982, acmcs::Kuck1977, sicomp::SavageJ1981, sicomp::StockmeyerV1984:409, jacm::Winograd1975, icalp::PaulVW1983} } @Article{GalperinW83, title={Succinct Representations of Graphs}, author={Hana Galperin and Avi Wigderson}, pages={183--198}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={stoc::Cook1971, tcs::Stockmeyer1976} } @Article{WitsenhausenW83a, title={On Storage Meda with Aftereffects}, author={H. S. Witsenhausen and A. D. Wyner}, pages={199--211}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={ic::RivestS1982} } @Article{Urzyczyn83a, title={A Necessary and Sufficient Condition in Order That a {Herbrand} Interpretation Be Expressive Relative to Recursive Programs}, author={Pawel Urzyczyn}, pages={212--219}, journal=iandc, month=mar, year=1983, volume=56, number=3, references={sicomp::ConstableG1972, sicomp::Cook1978, ic::Urzyczyn1983} } Author Index for Volume 56 -- page 220 April 1983 Volume 57, Number 1 @Article{Kamimura83, title={Tree Automata and Attribute Grammars}, author={Tsutomu Maimiura}, pages={1--20}, journal=iandc, month=apr, year=1983, volume=57, number=1, references={ic::AhoU1971:439, cacm::Bochmann1976:55, mst::ChiricaM1979, tcs::CourcelleF1982, ic::DuskePSS1977, jcss::EngelfrietRS1980, actai::EngelfrietF1981, ic::KamimuraS1981, actai::Kastens1980, popl::KennedyW1976, mst::Knuth1968, jcss::LewisRS1974, sicomp::Mayoh1981, jacm::Parikh1966, mst::RiisS1981:17, icalp::EngelfrietF1981, icalp::Saarinen1978} } @Article{Huynh83, title={Commutative Grammars: The Complexity of Uniform Word Problems}, author={Dung T. Huynh}, pages={21--39}, journal=iandc, month=apr, year=1983, volume=57, number=1, references={tcs::Hotz1980, jcss::HuntRS1976, tcs::JonesLL1977, stoc::Leeuwen1974, stoc::Mayr1981, stoc::StockmeyerM1973} } @Article{Kurtz83, title={On the Random Oracle Hypothesis}, author={Stuart A. Kurtz}, pages={40--47}, journal=iandc, month=apr, year=1983, volume=57, number=1, references={sicomp::BakerGS1975, sicomp::BennettG1981, tcs::Book1981, tcs::BookW1981, sicomp::BookLS1984:461} } @Article{StolboushkinT83, title={Deterministic Dynamic Logic is Strictly Weaker than Dynamic Logic}, author={A. P. Stolboushkin and M. A. Taitslin}, pages={48--55}, journal=iandc, month=apr, year=1983, volume=57, number=1, references={tcs::MeyerW1982, icalp::BermanHT1982} } @Article{Halpern83, title={Deterministic Process Logic is Elementary}, author={Joseph Y. Halpern}, pages={56--89}, journal=iandc, month=apr, year=1983, volume=57, number=1, abstract={Process Logic (PL) is a language for reasoning about the behavior of a program during a computation, while Propositional Dynamic Logic (PDL) can only reason about the input-output states of a program. Nevertheless, we show that to each PL model $M$, there corresponds in a natural way a PDL model $M^t$ such that each path in $M$ is represented by a state in $M^t$. Moreover, to every PL formula $p$, there corresponds a PDL formula $p^t$, whose length is linear in that of $p$, such that $p$ is true of a path in $M$ iff $p^t$ is true of the state which represents that path in $M^t$. We then show that $p$ is satisfiable iff $p^t$ is satisfiable in a finite PDL model with special properties which we call a {\em pseudomodel}. The size of the pseudomodel is in general nonelementary but is bounded by both the depth of nesting of the {\bf suf} operator and the alternation of the {\bf suf} and diamond operators. However, for DPL, a deterministic version of PL, the psuedomodel has exponential size, giving us a deterministic exponential time procedure for deciding DPL validity. These results suggest that it is the interaction between nondeterministic programs and the {\bf suf} operator that makes the general decision problem for PL so difficult.}, references={jcss::Ben-AriHP1982, stoc::ChandraHMP1981, stoc::EmersonH1982:169, jcss::EmersonH1985:1, jcss::FischerL1979, popl::GabbayPSS1980, focs::HalpernR1981, tcs::HalpernR1983:127, tcs::HalpernR1983:127, jcss::HarelKP1982, focs::Parikh1978, focs::Pnueli1977, focs::Pratt1976, jcss::Pratt1980, focs::Pratt1979, popl::Pratt1979, popl::ShermanPH1982, ipl::Harel1979}, preliminary={FOCS::Halpern1982} } May/June 1983 Volume 57, Numbers 2/3 @Article{Stockmeyer83, title={Optimal Orientations of Cells in Slicing Floorplan Designs}, author={Larry Stockmeyer}, pages={91--101}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, abstract={A methodology of VLSI layout described by several authors first determines the relative positions of indivisible pieces, called cells, on the chip. Various optimizations are then performed on this initial layout to minimize some cost measure such as chip area or perimeter. If each cell is a rectangle with given dimensions, one optimization problem is to choose orientations of all the cells to minimize the cost measure. A polynomial time algorithm is given for this optimization problem for layouts of a special type called slicings. However, orientation optimization for more general layouts is shown to be NP-complete (in the strong sense).} } @Article{GolsonR83, title={Connections Between Two Theories of Concurrency: Metric Spaces and Synchronization Trees}, author={William G. Golson and William C. Rounds}, pages={102--124}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, references={tcs::ArnoldN1980, IC::BakkerZ1982} } @Article{GoltzR83, title={The Non-sequential Behavior of {Petri} Nets}, author={U. Goltz and W. Resig}, pages={125--147}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, references={tcs::NielsenPW1981, tcs::Winkowski1982, icalp::FernandezT1982} } @Article{Wand83, title={Loops in Combinator-Based Compilers}, author={Mitchell Wand}, pages={148--164}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, abstract={In our paper [Wand 82a], we introduced a paradigm for compilation based on combinators. A program from a source language is translated (via a semantic definition) to trees of combinators; the tree is simplified via associative and distributive laws) to a linear, assembly-language-like format; the ``compiler writer's virtual machine'' operates by simulating a reduction sequence of the simplified tree. The correctness of these transformations follows from general results about the $\lambda$-calculus. The code produced by such a generator is always tree-like. In this paper, the method is extended to produce target code with explicit loops. This is done by re-introducing variables into the terms of the target language in a restricted way, along with a structured binding operator. We also consider general conditions under which these transformations hold.}, references={JALGE::ArbibM1980, JACM::ArbibM1982:577, BOOK::Barendregt1981, BOOK::MilneC1976, MISC::Mosses1982, LNCS::RaskovskyC1980, ICALP::Sethi1981, TOPLAS::Sethi1983, TCS::ThatcherWW1981, JSYML::Turing1937, SPE::Turner1979, ACTAI::Wand1980, TR::Wand1980, POPL::Wand1982, TOPLAS::Wand1982}, preliminary={popl::Wand1983} } @Article{Csirmaz83, author={L. Csirmaz}, title={On the Strength of ``Sometimes'' and ``Always'' in Program Verification}, pages={165--179}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, references={tcs::AndrekaNS1982:193, tcs::AndrekaNS1982:259, sicomp::Cook1978, tcs::Csirmaz1981, cacm::MannaW1978} } @Article{Grandjean83, title={Complexity of the First-Order Theory of Almost All Finite Structures}, author={Etienne Grandjean}, pages={180--204}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, references={tcs::Berman1980, tcs::BrussM1980, jacm::ChandraKS1981, jsyml::Fagin1976, tcs::FerranteG1977, jcss::Immerman1982, mst::Lynch1982, jcss::Paterson1972, actai::PaulPR1980, jcss::Ruzzo1980, jcss::Savitch1970, actai::Savitch1973, jcss::Seiferas1977, jcss::Seiferas1977, jacm::SeiferasFM1978, tcs::Stockmeyer1976, stoc::StockmeyerM1973} } @Article{RestivoR83, title={Some Applications of a Theorem of {Shirshov} to Language Theory}, author={Antonio Restivo and Christophe Reutenauer}, pages={205--213}, journal=iandc, month=may # "/" # jun, year=1983, volume=57, number={2/3}, references={sicomp::EhrenfeuchtPR1981} } July/August/September 1983 Volume 58, Numbers 1-3 @Article{LorencL83, title={Discrete Random Process Stabilization}, author={Aivar A. Lorenc and J{\=a}nis K. Lapi{\c{n}}{\v{s}}}, pages={1--18}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={ic::Gelenbe1970, Lorenc1976:295} } @Article{SteyaertF83, title={Patterns and Pattern-Matching in Trees: An Analysis}, author={Jean-Marc Steyaert and Philippe Flajolet}, pages={19--58}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={tcs::BerstelR1982, cacm::BoyerM1977, jcss::FlajoletO1982, tcs::FlajoletRV1979, focs::FlajoletS1981, stoc::KarpMR1972, actai::Kemp1979, sicomp::KnuthMP1977, jacm::HoffmannO1982} } @Article{Urzyczyn83b, title={Nontrivial Definability by Flow-Chart Programs}, author={Pawe{\l} Urzyczyn}, pages={59--87}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={jcss::Kfoury1974, tcs::Kfoury1983, mst::LynchB1979, ic::StolboushkinT1983, focs::Tiuryn1981, ic::Urzyczyn1981, ic::Urzyczyn1983, icalp::BermanHT1982} } @Article{GasarchH83, title={Relativizations Comparing {{\em NP\/}} and Exponential Time}, author={W. Ian Gasarch and Steven Homer}, pages={88--100}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, abstract={We construct oracles that force all possible relationships between $NP$ and $EXP_k = DTIME (2^{O(n^k)})$. We then obtain these results with immunity, and, in some cases, bi-immunity. In addition, for almost all oracles, these classes are incomparble.}, references={sicomp::BakerGS1975, tcs::BakerS1979, sicomp::BennettG1981:96, sicomp::Book1972, tcs::HomerM1983, mst::LadnerL1976, jacm::Rackoff1982} } @Article{Cosmadakis83, title={The Complexity of Evaluating Relational Queries}, author={Stavros Cosmadakis}, pages={101--112}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={sicomp::AhoSU1979, stoc::ChandraM1977, cacm::Codd1970, stoc::Cook1971, stoc::DeMilloL1980, jacm::MaierSY1981, stoc::PapadimitriouY1982, tcs::Stockmeyer1976, jacm::SagivY1980, sicomp::Valiant1979, tcs::Wrathall1976} } @Article{BorodinCP83, title={Parallel Computation for Well-Endowed Rings and Space-Bounded Probabilistic Machines}, author={A. Borodin and S. Cook and N. Pippenger}, pages={113--136}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={sicomp::Borodin1977, focs::BorodinGH1982, sicomp::Csanky1976, sicomp::Gill1977, tcs::GillHS1980, jacm::LadnerF1980, focs::Pippenger1979, jcss::Ruzzo1981, jcss::Savitch1970, tcs::Simon1981, stoc::Simon1981, focs::SimonGH1978, jacm::Winograd1965, jacm::Winograd1967, mfcs::Jung1981} } @Article{MehlhornP83, title={Area-Time Optimal {VLSI} Integer Multiplier with Minimum Computation Time}, author={Kurt Mehlhorn and Franco P. Preparata}, pages={137--156}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={cacm::AbelsonA1980, jacm::BrentK1981, cacm::PreparataV1981, stoc::Thompson1979, icalp::PreparataV1981} } @Article{Ko83, title={On the Computational Complexity of Ordinary Differential Equations}, author={Ker-I Ko}, pages={157--194}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={ic::Book1974, jcss::Cleave1969, jcss::Ko1983, tcs::KoF1982, jcss::Miller1970, stoc::StockmeyerM1973, icalp::Schnorr1976} } @Article{WitsenhausenW83b, title={Erratum: On Storage Media with Aftereffects}, author={H. S. Witsenhausen and A. D. Wyner}, pages={195}, journal=iandc, month=jul # "/" # aug # "/" # sep, year=1983, volume=58, number={1--3}, references={ic::WitsenhausenW1983:199} } Author Index for Volume 58 -- page 196 October/November/December 1983 Volume 59, Numbers 1-3 @Article{YamasakiD83, title={The Satisfiability Problem for a Class Consisting of {Horn} Sentences and Some Non-{Horn} Sentences in Proportional Logic}, author={Susumu Yamasaki and Shuji Doshita}, pages={1--12}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={stoc::Cook1971, tcs::Galil1977, jacm::HenschenW1974, tcs::JonesL1976, jacm::Joyner1976} } @Article{EhrenfeuchtR83, title={Repetition of Subwords in {DOL} Languages}, author={A. Ehrenfeucht and G. Rozenberg}, pages={13--35}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={mst::Cobham1972, ic::EhrenfeuchtR1978, tcs::EhrenfeuchtR1981} } @Article{Hennessy83, title={Synchronous and Asynchronous Experiments on Processes}, author={M. Hennessy}, pages={36--83}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={focs::CourcelleN1976, tcs::NicolaH1984:83, jcss::FrancezHLR1979, jacm::GoguenTWW1977:68, ic::Hennessy1981, tcs::Milner1983, focs::RoundsB1981, jcss::Smyth1978, tcs::AustryB1984:91, icalp::NicolaH1983:548} } @Article{BaranyF83, title={Mental Poker with Three or More Players}, author={Imre B{\'a}r{\'a}ny and Zolt{\'a}n F{\"u}redi}, pages={84--93}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={stoc::GoldwasserM1982:365} } @Article{Stolboushkin83, title={Regular Dynamic Logic Is Not Interpretable in Deterministic Context-Free Dynamic Logic}, author={A. P. Stolboushkin}, pages={94--107}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={ic::StolboushkinT1983} } @Article{Schmeck83, title={Algebraic Semantics of Recursive Flowchart Schemes}, author={Hartmut Schmeck}, pages={108--126}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={tcs::BloomT1979, tcs::Courcelle1983, tcs::Cousineau1980, ieeetse::Elgot1976, tcs::ElgotS1979, tcs::Gallier1981:193, tcs::Gallier1981:239, jcss::Gallier1981, jcss::Ginali1979, jacm::goguenTWW1977, sicomp::HechtU1972, jacm::HechtU1974, jcss::Schmeck1983, tcs::ThatcherWW1981, focs::WrightTWG1976} } @Article{BarendregtR83, title={Semantics for Classical {AUTOMATH} and Related Systems}, author={Henk Barendregt and Adrian Rezus}, pages={127--147}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={sicomp::Scott1976} } @Article{Staiger83, title={Subspaces of {${\rm GF}(q)^{w}$} and Convolutional Codes}, author={Ludwig Staiger}, pages={148--183}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={ic::Forney1974:222, ic::Kuich1970, ic::Linna1976, ic::Piret1978, jcss::Staiger1983, ic::Wagner1979} } @Article{Weiss83, title={An $n^{3/2}$ Lower Bound on the Monotone Network Complexity of the {Boolean} Convolution}, author={J{\"u}rgen Weiss}, pages={184--188}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1983, volume=59, number={1--3}, references={tcs::Blum1984:337, focs::Blum1981, actai::Mehlhorn1979, tcs::Paterson1975, sicomp::Pratt1975, tcs::Wegener1982, tcs::Wegener1979} } Author Index for Volume 59 -- page 189 Cumulative Subject Index for Volume 59 -- pages 190-195 January/February/March 1984 Volume 60, Numbers 1-3 @Article{DurisGPR84, oldkey={ReischukDPG84}, title={Two Nonlinear Lower Bounds for On-Line Computations}, author={Pavol D{\=u}ri{\=s} and Zvi Galil and Wolfgang Paul and Ruediger Reischuk}, pages={1--11}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } @Article{Tiuryn84, title={Unbounded Program Memory Adds to the Expressive Power of First-Order Programming Logic}, author={Jerzy Tiuryn}, pages={12--35}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3}, preliminary={focs::Tiuryn1981:335} } @Article{FalaschiLP84, title={A Synchronization Logic: Axiomatics and Formal Semantics of Generalized {Horn} Clauses}, author={M. Falaschi and G. Levi and C. Palamidessi}, pages={36--69}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3}, abstract={An extension of Horn Clause Logic is defined based on the introduction of a synchronization operator. Generalized Horn Clauses (GHC) are introduced though an informal descriptionof their operational semantics, which allows discussion of some typical synchronization problems. GHC are first considered formally as a programming language by defining the syntax, the operational semantics, the model-theoretic semantics, and the fixed-point sematics. The above mentioned semantics are given in the van Emden-Kowalski style (1976, \emph{J.\ Assoc.\ Comput.\ Mach.}\ 23, 733--742) and are proved equivalent. GHC are then characterized as axiomatic theories. A set of axiom schemata concerned with the newly introduced synchronization operator is defined and it is proved that the operational semantics inference rule is both sound and complete. Finally, the relation between GHC and Horn Clauses is analyzed, and it is proved that Horn Clause Logic is strictly included in the Generalized Horn Clause Logic.}, xxx-references={JACM::AptE82, JACM::EmdenK76, JACM::Robinson65} } @Article{Loui84, title={The Complexity of Sorting on Distributed Systems}, author={Michael C. Loui}, pages={70--85}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } @Article{HarelP84, title={On Static Logics, Dynamic Logics, and Complexity Classes}, author={D. Harel and D. Peleg}, pages={86--102}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3}, abstract={Several versions of quantified dynamic logic are shown to be equivalent in expressive power to ``static'' extensions of classical logics. Consequently, by recent results of various researchers, many connections between dynamic logics and complexity classes are obtained. Among other things, a sequence of dynamic logics of increasing expressive power, which correspond, over appropriate finite structures, to LOGSPACE, PTIME, and PSPACE, as well as to the sets of definable in the logarithmic-space, polynomial-time, and arithmetical hierarchies is exhibited.} } @Article{WidmayerS84, title={On the Complexity of Concurrency Control by Locking in Distributed Database Systems}, author={Eljas Soisalon-Soininen and Peter Widmayer}, pages={103--108}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } @Article{BergstraK84, title={Process Algebra for Synchronous Communication}, author={J. A. Bergstra and J. W. Klop}, pages={109--137}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } @Article{BackM84, title={A Semantic Approach to Program Modularity}, author={R. J. R. Back and H. Mannila}, pages={138--167}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } @Article{Kazakos84, title={A Game Theoretic Approach to Robust Filtering}, author={P. Papantoni-Kazakos}, pages={168--191}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1984, volume=60, number={1--3} } Author Index for volume 60 -- page 192 April 1984 Volume 61, Number 1 @Article{CoffmanG84, title={Dynamic, First-Fit Packings in Two or More Dimensions}, author={Coffman, Jr., E. G. and E. N. Gilbert}, pages={1--14}, journal=iandc, month=apr, year=1984, volume=61, number=1 } @Article{Levin84, title={Randomness Conservation Inequalities; Information and Independence in Mathematical Theories}, author={Leonid A. Levin}, pages={15--37}, journal=iandc, month=apr, year=1984, volume=61, number=1 } @Article{MohanFS84, title={Compatibility and Commutativity of Lock Modes}, author={C. Mohan and D. Fussell and A. Silberschatz}, pages={38--64}, journal=iandc, month=apr, year=1984, volume=61, number=1 } @Article{GurevichL84, title={A Logic for Constant-Depth Circuits}, author={Yuri Gurevich and Harry R. Lewis}, pages={65--74}, journal=iandc, month=apr, year=1984, volume=61, number=1, abstract={We present an extension of first-order logic that captures precisely the computational complexity of (the uniform sequences of) constant-depth polynomial-time circuits.} } May 1984 Volume 61, Number 2 @Article{BeeriV84, title={On Acyclic Database Decompositions}, author={Catriel Beeri and Moshe Y. Vardi}, pages={75--84}, journal=iandc, month=may, year=1984, volume=61, number=2, references={ACMTDS::AhoBU1979, ICVLDB::BeeriBG1978, JACM::BeeriFMY1983, SICOMP::BeeriH1981, JACM::BeeriV1984:718, JCSS::CasanovaFP1984, PODS::Cosmadakis1983:317, ACMTDS::Fagin1977, JACM::Fagin1982:952, ACMTDS::FaginMU1982, ACMTDS::GoodmanS1982, STOC::KanellakisCV1983:264, ACMTDS::Rissanen1977, SICOMP::TarjanY1984, FOCS::Vardi1982:176, ACTAI::Vardi1983} } @Article{ThiagarajanV84, title={A Fresh Look at Free Choice Nets}, author={P. S. Thiagarajan and K. Vos}, pages={85--113}, journal=iandc, month=may, year=1984, volume=61, number=2, references={JCSS::CommonerHEP1971, TCS::GenrichL1981, TCS::Jensen1981, SICOMP::JumpT1973, JACM::JumpT1975, BOOK::Milner1980} } @Article{Doberkat84, author={Ernst E. Doberkat}, title={An Average Case Analysis of {Floyd's} Algorithm to Construct Heaps}, pages={114--131}, journal=iandc, month=may, year=1984, volume=61, number=2, references={BOOK::AhoHU1974, IPL::Doberkat1982, CACM::Floyd1964} } @Article{FengT84, title={On Quasi-Perfect Property of Double-Error-Correcting Goppa Codes and Their Complete Decoding}, author={G. L. Feng and K. K. Tzeng}, pages={132--146}, journal=iandc, month=may, year=1984, volume=61, number=2, references={IC::GorensteinPZ1960:291} } @Article{Schmitt84, title={Diamond Formulas: A Fragment of Dynamic Logic with Recursively Enumerable Validity Problem}, author={Peter H. Schmitt}, pages={147--158}, journal=iandc, month=may, year=1984, volume=61, number=2, references={MST::Engeler1967, STOC::HarelMP1977, JACM::MeyerH1982:555} } @Article{EvenSY84, title={The Complexity of Promise Problems with Applications to Public-Key Cryptography}, author={Shimon Even and Alan L. Selman and Yacov Yacobi}, pages={159--173}, journal=iandc, month=may, year=1984, volume=61, number=2, references={BOOK::GareyJ1979, JACM::Ladner1975:155, TCS::LadnerLS1975:103, STOC::PapadimitriouY1982, JACM::Rackoff1982:261, IC::Ullian1967} } @Article{YamasakiD84, title={Erratum: The Satisfiability Problem for a Class Consisting of {Horn} Sentences and Non-{Horn} Sentences in Proportional Logic}, author={Susumu Yamasaki and Shuji Doshita}, pages={174}, journal=iandc, month=may, year=1984, volume=61, number=2, references={YamasakiD1983:1} } June 1984 Volume 61, Number 3 @Article{EmersonS84, title={Deciding Full Branching Time Logic}, author={E. Allen Emerson and A. Prasad Sistla}, pages={175--201}, journal=iandc, month=jun, year=1984, volume=61, number=3 } @Article{Broy84, title={Semantics of Communicating Processes}, author={Manfred Broy}, pages={202--246}, journal=iandc, month=jun, year=1984, volume=61, number=3 } @Article{Niwinski84, title={Fixed-Point Characterization of Context-Free $\infty$-Languages}, author={Damian Niwi{\'n}ski}, pages={247--276}, journal=iandc, month=jun, year=1984, volume=61, number=3 } Author Index for Volume 61 -- page 277 July 1984 Volume 62, Number 1 @Article{WijshoffL84, title={Arbitrary versus Periodic Storage Schemes and Tessellations of the Plane Using One Type of Polyomino}, author={H. A. G. Wijshoff and J. van Leeuwen}, pages={1--25}, journal=iandc, month=jul, year=1984, volume=62, number=1 } @Article{ItzhaikY84, title={An Intermediate Machine Technique for Deciding Equivalence between a {DPDA} and a Linear {DPDA}}, author={Yair Itzhaik and Amiram Yehudai}, pages={26--35}, journal=iandc, month=jul, year=1984, volume=62, number=1 } @Article{GianniniL84, title={Effectively Given Domains and Lambda-Calculus Models}, author={Paola Giannini and Giuseppe Longo}, pages={36--63}, journal=iandc, month=jul, year=1984, volume=62, number=1 } @Article{Krichevsky84, title={Optimal Hashing}, author={R. E. Krichevsky}, pages={64--92}, journal=iandc, month=jul, year=1984, volume=62, number=1 } August/September 1984 Volume 62, Numbers 2/3 @Article{LadnerSL84, title={Alternation Bounded Auxiliary Pushdown Automata}, author={Richard E. Ladner and Larry J. Stockmeyer and Richard J. Lipton}, pages={93--108}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3}, abstract={Languages accepted by alternating auxiliary pushdown automata using simultaneously $a(n)$ alternations and $s(n)$ space are shown to be members of the class of languages accepted by nondeterministic Turing machines using $a(n)2^{cs(n)}$ space for some $c > 0$. This result is used to show that the hierarchy of classes of languages accepted by pushdown automata based on the number of alternations collapses at the second level of the hierarchy. The power of alternation bounded pushdown automata without auxiliary storage is also investigated.} } @Article{Hong84, title={On Similarity and Duality of Computation ({I})}, author={Jia-Wei Hong}, pages={109--128}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3} } @Article{Wegener84, title={Optimal Decision Trees and One-Time-Only Branching Programs for Symmetric {Boolean} Functions}, author={Ingo Wegener}, pages={129--143}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3} } @Article{MainB84, title={Functional Behvior of Nondeterministic and Concurrent Programs}, author={Michael G. Main and David B. Benson}, pages={144--189}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3} } @Article{LundeliusL84, title={An Upper and Lower Bound for Clock Synchronization}, author={Jennifer Lundelius and Nancy Lynch}, pages={190--204}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3}, abstract={The problem of synchronizing clocks of processes in a fully connected network is considered. It is proved that, even if the clocks all run at the same rate as real time and there are no failures, an uncertainty of $\epsilon$ in the message delivery time makes it impossible to synchronize the clocks of $n$ processes any more closely than $\epsilon(1 - 1/n)$. A simple algorithm is given that achieves this bound.} } @Article{Friedman84, title={On the Spectra of Universal Relational Sentences}, author={Harvey Friedman}, pages={205--209}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3} } @Article{MunroP84, title={Fault Tolerance and Storage Reduction in Binary Search Trees}, author={J. Ian Munro and Patricio V. Poblete}, pages={210--218}, journal=iandc, month=aug # "/" # sep, year=1984, volume=62, number={2/3} } Author Index for Volume 62 -- page 219 October/November 1984 Volume 63, Numbers 1/2 @Article{Arazi84, title={An Approach for Generating Different Types of Gray Codes}, author={Benjamin Arazi}, pages={1--10}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{Feldman84, title={A Decidable Propositional Dynamic Logic with Explicit Probabilities}, author={Yishai A. Feldman}, pages={11--38}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{ColeY84, title={Geometric Retrieval Problems}, author={Richard Cole and Chee K. Yap}, pages={39--57}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{NarendranOW84, title={The Uniform Conjugacy Problem for Finite {Church}-{Rosser} {Thue} Systems is {NP}-Complete}, author={Paliath Narendran and Friedrich Otto and Karl Winklmann}, pages={58--66}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{Robson84, title={Fast Probabilistic {RAM} Simulation of Single Tape {Turing} Machine Computations}, author={J. M. Robson}, pages={67--87}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{SistlaCFNM84, title={Can Message Buffers Be Axiomatized in Linear Temporal Logic?}, author={A. P. Sistla and E. M. Clarke and N. Francez and A. R. Meyer}, pages={88--112}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2}, abstract={Message passing is one of the primary modes of interprocess communication in a distributed system. In this paper we investigate the possibility of {\em characterizing\/} and {\em axiomatizing\/} different message passing systems in temporal logic. Specifically, we consider FIFO buffers (queues), LIFO buffers (stacks) and unordered buffers (bags). We show that all bounded buffers are characterizable in propositional temporal logic (PTL) and so are axiomatizable. We prove that the theory of unbounded FIFO buffers is $\pi^1_1$-complete and so is not axiomatizable. We also prove that the theories of unbounded LIFO and unordered buffers are decidable and hence are axiomatizable.}, xxx-references={Wolper83} } @Article{KleijnPRS84, title={Direction Independent Context-Sensitive Grammars}, author={H. C. M. Kleijn and M. Penttonen and G. Rozenberg and K. Salomaa}, pages={113--117}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2} } @Article{HarelK84, title={A Programming Language for the Inductive Sets, and Applications}, author={David Harel and Dexter Kozen}, pages={118--139}, journal=iandc, month=oct # "/" # nov, year=1984, volume=63, number={1/2}, abstract={We describe a programming language IND that generalizes alternating Turing machines to arbitrary first-order structures. We show that IND programs (resp.\ everywhere-halting IND programs, loop-free IND programs) accept precisely the inductively definable (resp.\ hyperelementary, elementary) relations. We give several examples showing how the language provides a robust and computational approach to the theory of first-order inductive definability. We then show: (1)~on all acceptable structures (in the sense of Moschovakis {\em Elementary Induction on Abstract Structures}, North-Holland, Amsterdam, 1974), r.e.\ dynamic logic is more expressive than finite-test dynamic logic. This refines a separation result of Meyer and Parikh (``Proc.\ 12th ACM Sympos.\ on Theory of Computing,'' 1979, pp.\ 167--175); (2)~IND provides a natural query language for the set of fixpoint queries over a relational database, answering a question of Chandra and Harel ({\em J.\ Comput.\ System Sci.} {\bf 25}, No.~1 (1982), 99--128).} } December 1984 Volume 63, Number 3 @Article{Guting84, title={Dynamic {$C$}-Oriented Polygonal Intersections Searching}, author={Ralf Hartmut G{\"u}ting}, pages={143--163}, journal=iandc, month=dec, year=1984, volume=63, number=3 } @Article{FranzblauK84, title={An Algorithm for Covering Polygons with Rectangles}, author={D. S. Franzblau and D. J. Kleitman}, pages={164--189}, journal=iandc, month=dec, year=1984, volume=63, number=3 } @Article{EhrenfeuchtR84, title={An Easy Proof of {Greibach} Normal Form}, author={Andrzej Ehrenfeucht and Grzegorz Rozenberg}, pages={190--199}, journal=iandc, month=dec, year=1984, volume=63, number=3 } @Article{GoudaMY84, title={On the Progress of Communications between Two Finite State Machines}, author={M. G. Gouda and E. G. Manning and Y. T. Yu}, pages={200--216}, journal=iandc, month=dec, year=1984, volume=63, number=3 } @Article{AjtaiFK84, title={Hash Functions for Priority Queues}, author={M. Ajtai and M. Fredman and J. Koml{\`o}s}, pages={217--225}, journal=iandc, month=dec, year=1984, volume=63, number=3 } Author Index for Volume 63 -- page 226 Cumulative Subject Index for Volumes 60-63 -- pages 227-231 January/February/March 1985 Volume 64, Numbers 1-3 Special Issue International Conference on "Foundations of Computation Theory" M. Karpinski and J. van Leeuwen, Special Issue Editors @Article{KarpinskiL85, title={Preface}, author={M. Karpinski and J. van Leeuwen}, pages={1}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{Cook85, title={A Taxonomy of Problems with Fast Parallel Algorithms}, author={Stephen A. Cook}, pages={2--21}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{Reischuk85, title={A New Solution for the {Byzantine} Generals Problem}, author={R{\"u}diger Reischuk}, pages={23--42}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{FurstLS85, title={Pseudorandom Number Generation and Space Complexity}, author={Merrick Furst and Richard Lipton and Larry Stockmeyer}, pages={43--51}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3}, abstract={Blum and Micali (1982) have described a pseudorandom number generator that transforms $m$-bit seeds to $m^k$-bit pseudorandom numbers, for any integer $k$. Under the assumption that the discrete logarithm problem cannot be solved by polynomial-size combinational logic circuits, they show that the pseudorandom numbers generated are good in the sense that no polynomial-size circuit can determine the $t$-th bit given the 1st through $(t-1)$-th bits, with better than 50\%\ accuracy. Yao (1982) has shown under the same assumption about the nonpolynomial complexity of the discrete logarithm problem, that these pseudorandom numbers can be used in place of truly random numbers by any polynomial-time probabilistic Turing machine. Thus, given a time $n^k$ probabilistic Turing machine $M$ and given any $\epsilon > 0$, a deterministic Turing machine can simulate $M$ by cycling through all seeds of length $n^\epsilon$, giving a deterministic simulation in time $2^{n^\epsilon}$, an improvement over the time $2^{n^k}$ taken by the obvious simulation. Yao also shows that other problems, for example, integer factorization, can be used instead of the discrete logarithm in the intractability assumption. The purpose of this paper is to observe that these intractability assumptions have implications toward space complexity. Two implications are that random time $T(n)$ is contained in deterministic space $T(n)/\log T(n)$, and checking whether a bipartite graph has a perfect matching can be done in space $n^\epsilon$, for any $\epsilon > 0$.} } @Article{HertelM85, title={Fast Triangulation of the Plane with Respect to Simple Polygons}, author={Stefan Hertel and Kurt Mehlhorn}, pages={52--76}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{Chazelle85, title={How to Search in History}, author={Bernard Chazelle}, pages={77--99}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{Ukkonen85, title={Algorithms for Approximate String Matching}, author={Esko Ukkonen}, pages={100--118}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } @Article{HarelS85, title={Propositional Dynamic Logic of Flowcharts}, author={D. Harel and R. Sherman}, pages={119--135}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3}, abstract={Following a suggestion of Pratt, we consider propositional dynamic logic in which programs are nondeterministic finite automata over atomic programs and tests (i.e., flowcharts), rather than regular expressions. While the resulting version of PDL, call it APDL, is clearly equivalent in expressive power to PDL, it is also (in the worst case) exponentially more succinct. In particular, deciding its validity problem by reducing it to that of PDL leads to a double exponential time procedure, although PDL itself is decidable in exponential time. We present an elementary combined proof of the completeness of a simple axiom system for APDL and decidability of the validity problem in exponential time. The results are thus stronger than those for PDL, since PDL can be encoded in APDL with no additional cost, and the proofs simpler, since induction on the structure of programs is virtually eliminated. Our axiom system for APDL relates to the PDL system just as Floyd's proof method for partial correctness relates to Hoare's.} } @Article{Nicola85, title={Two Complete Axiom Systems for a Theory of Communicating Sequential Processes}, author={Rocco De Nicola}, pages={136--172}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1985, volume=64, number={1--3} } Author Index for Volume 64 -- page 173 April 1985 Volume 65, Number 1 @Article{GrantM85, title={Normalization and Axiomatization for Numerical Dependencies}, author={John Grant and Jack Minker}, pages={1--17}, journal=iandc, month=apr, year=1985, volume=65, number=1 } @Article{IbarraR85a, title={The Equivalence Problem and Correctness Formulas for a Simple Class of Programs}, author={Oscar H. Ibarra and Louis E. Rosier}, pages={18--41}, journal=iandc, month=apr, year=1985, volume=65, number=1 } @Article{IbarraR85b, title={On Simple Programs with Primitive Conditional Statements}, author={Oscar H. Ibarra and Louis E. Rosier}, pages={42--62}, journal=iandc, month=apr, year=1985, volume=65, number=1 } @Article{Ambos-spies85, title={Sublattices of the Polynomial Time Degrees}, author={Klaus Ambos-Spies}, pages={63--84}, journal=iandc, month=apr, year=1985, volume=65, number=1 } May/June 1985 Volume 65, Numbers 2/3 @Article{Statman85, title={Logical Relations and the Typed $\lambda$-Calculus}, author={R. Statman}, pages={85--97}, journal=iandc, month=may # "/" # jun, year=1985, volume=65, number={2/3} } @Article{Kfoury85, title={Definability by Deterministic and Non-deterministic Programs (with Applications to First-Order Dynamic Logic)}, author={A. J. Kfoury}, pages={98--121}, journal=iandc, month=may # "/" # jun, year=1985, volume=65, number={2/3} } @Article{Dershowitz85, title={Computing with Rewrite Systems}, author={Nachum Dershowitz}, pages={122--157}, journal=iandc, month=may # "/" # jun, year=1985, volume=65, number={2/3} } @Article{HartmanisIS85, title={Sparse Sets in {NP-P}: {EXPTIME} versus {NEXPTIME}}, author={J. Hartmanis and N. Immerman and V. Sewelson}, pages={158--181}, journal=iandc, month=may # "/" # jun, year=1985, volume=65, number={2/3} } @Article{Plaisted85, title={Semantic Confluence Tests and Completion Methods}, author={David A. Plaisted}, pages={182--215}, journal=iandc, month=may # "/" # jun, year=1985, volume=65, number={2/3} } Author Index for Volume 65 -- page 216 July/August 1985 Volume 66, Numbers 1/2 @Article{Kannan85, title={Unraveling $k$-page graphs}, author={Ravi Kannan}, pages={1--5}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{Rounds85, title={On the Relationship between {Scott} Domains, Synchronization Trees, and Metric Spaces}, author={William C. Rounds}, pages={6--28}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{Grabowski85, title={On Relative Completeness of {Hoare} Logics}, author={Michal Grabowski}, pages={29--44}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{Blum85, title={An Area-Maximum Edge Length Trade-off for {VLSI} Layout}, author={Norbert Blum}, pages={45--52}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{AfratiPP85, title={The Complexity of Cubical Graphs}, author={Foto Afrati and Christos H. Papadimitriou and George Papageorgiou}, pages={53--60}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{Frederickson85, title={Implicit Data Structures for Weighted Elements}, author={Greg N. Frederickson}, pages={61--82}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2}, abstract={Several new data structures are presented for dictionaries containing elements with different weights (access probabilities). The structures use just one location in addition to those required for the values of the elements. The first structure supports a worst-case search time that is within a constant multiplicative factor of optimal, in terms of the rank of the weight of the desired element with respect to the multiset of weights. If the values of the elements that comprise the dictionary have been drawn from a uniform distribution, then a variation of this structure achieves average search times that are asymptotically very good. Similar results are established for data structures which handle the case in which the intervals between consecutive dictionary values also have access probabilities. Lower bounds are presented for the worst-case search complexity.} } @Article{GrumbergFR85, title={A Proof Rule for Fair Termination of Guarded Commands}, author={Orna Grumberg and Nissim Francez and Johann A. Makowsky and William P. de Roever}, pages={83--102}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } @Article{Huynh85, title={The Complexity of Equivalence Problems for Commutative Grammars}, author={Dung T. Huynh}, pages={103--121}, journal=iandc, month=jul # "/" # aug, year=1985, volume=66, number={1/2} } September 1985 Volume 66, Number 3 @Article{Kaltofen85, title={Effective {Hilbert} Irreducibility}, author={Erich Kaltofen}, pages={123--137}, journal=iandc, month=sep, year=1985, volume=66, number=3 } @Article{Adachi85, title={Powerposets}, author={Takanori Adachi}, pages={138--162}, journal=iandc, month=sep, year=1985, volume=66, number=3 } @Article{Stern85, title={Complexity of Some Problems from the Theory of Automata}, author={Jacques Stern}, pages={163--176}, journal=iandc, month=sep, year=1985, volume=66, number=3 } @Article{Amir85, title={Separation in Nonlinear Time Models}, author={Amihood Amir}, pages={177--203}, journal=iandc, month=sep, year=1985, volume=66, number=3 } Author Index for Volume 66 -- page 206 October/November/December 1985 Volume 67, Numbers 1-3 Symposium: Mathematical Foundations of Computer Science @Article{Tiuryn85, title={Preface}, author={Jerzy Tiuryn}, pages={1}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3} } @Article{Robson85, title={Alternation with Restrictions on Looping}, author={J. M. Robson}, pages={2--11}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={JACM::ChandraKS81, JACM::LichtensteinS80} } @Article{Rytter85, title={Fast Recognition of Pushdown Automaton and Context-free Languages}, author={Wojciech Rytter}, pages={12--22}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={AhoHU68, STOC::GrahamHR76} } @Article{HennessyS85, title={The Power of the Future Perfect in Program Logics}, author={Matthew Hennessy and Colin Stirling}, pages={23--52}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={JACM::HennessyM85, FOCS::Wolper81} } Regular Articles @Article{BalcazarDG85, title={Uniform Characterizations of Non-Uniform Complexity Measures}, author={Jos{\'e} L. Balc{\'a}zar and Josep D{\'\i}az and Joaquim Gabarr{\'o}}, pages={53--69}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::BorodinDFP83, JACM::Cook71, JACM::HopcroftU69, STOC::KarpL80, JACM::Lynch77} } @Article{BlassGK85, title={A Zero-One Law for Logic with a Fixed-Point Operator}, author={Andreas Blass and Yuri Gurevich and Dexter Kozen}, pages={70--90}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, abstract={The logic obtained by adding the least-fixed-point operator to first-order logic was proposed as a query language by Aho and Ullman ({\em in\/} ``Proc.\ 6th ACM Sympos.\ on Principles of Programming Languages,'' 1979, pp.\ 110-120) and has been studied, particularly in connection with finite models, by numerous authors. We extend to this logic, and to the logic containing the more powerful iterative-fixed-point operator, the zero-one law proved for first-order logic in (Glebskii, Kogan, Liogonki, and Talanov (1969), {\em Kibernetika\/} {\bf 2}, 31-42; Fagin (1976), {\em J. Symbolic Logic\/} {\bf 41}, 50-58). For any sentence $\varphi$ of the extended logic, the proportion of models of $\varphi$ among all structures with universe $\{1,2,\ldots, n \}$ approaches 0 or 1 as $n$ tends to infinity. We also show that the problem of deciding, for any $\varphi$, whether this proportion approaches 1 is complete for exponential time, if we consider only $\varphi$'s with a fixed finite vocabulary (or vocabularies of bounded arity) and complete for double-exponential time if $\varphi$ is unrestricted. In addition, we establish some related results.}, xxx-references={JACM::ChandraKS81, STOC::Cook71, STOC::Immerman82, STOC::Vardi82} } @Article{Vishkin85, title={Optimal Parallel Pattern Matching in Strings}, author={Uzi Vishkin}, pages={91--113}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={FOCS::AggarwalCGOY85, STOC::AwerbuchIS84, STOC::BorodinH82, STOC::Galil84, FOCS::LandauV85, FOCS::Reischuk81, STOC::ReifV83, STOC::Vishkin84} } @Article{IbarraKR85a, title={Some Characterizations of Multihead Finite Automata}, author={Oscar H. Ibarra and Sam M. Kim and Louis E. Rosier}, pages={114--125}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={AhoHU68, Igarashi78, STOC::Sudborough76} } @Article{IbarraKR85b, title={On Space and Time Efficient {TM} Simulations of Some Restricted Classes of {PDA}'s}, author={Oscar H. Ibarra and Sam M. Kim and Louis E. Rosier}, pages={126--143}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::Cook79, Igarashi78, FOCS::LewisSH65, JACM::Lynch77, Moriya73a, RitchieS72, JACM::Sudborough75, Valiant74, FOCS::Verbeek81, BraunmuhlCMV83, FOCS::BraunmuhlV80} } @Article{Galil85, title={Optimal Parallel Algorithms for String Matching}, author={Zvi Galil}, pages={144--157}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::BorodinH82, STOC::CookD82, STOC::KarpMR72, FOCS::PreparataV79} } @Article{KarpinskiV85, title={There Is No Polynomial Deterministic Space Simulation of Probabilistic Space with a Two-Way Random-Tape Generator}, author={Marek Karpinski and Rutger Verbeek}, pages={158--162}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::AdlemanM77, JACM::Blum67, BorodinCP83, STOC::BabaiGM82} } @Article{Szwerinski85, title={Symmetrical One-Dimensional Cellular Spaces}, author={Helge Szwerinski}, pages={163--172}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={Smith71b} } @Article{Tsakalidis85, title={{AVL}-Trees for Localized Search}, author={Athanasios K. Tsakalidis}, pages={173--194}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::GuibasMPR77, STOC::Kosaraju81} } @Article{Heide85, oldkey={Meyer85}, title={Lower Time Bounds for Solving Linear Diophantine Equations on Several Parallel Computational Models}, author={Friedhelm {Meyer auf der Heide}}, pages={195--211}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::FortuneW78, JACM::Reischuk87, JACM::GalilP83, STOC::Ben-Or83, STOC::Yao81, JACM::Heide85, JACM::Waksman68} } @Article{Wegener85, title={The Critical Complexity of All (Monotone) {Boolean} Functions and Monotone Graph Properties}, author={Ingo Wegener}, pages={212--222}, journal=iandc, month=oct # "/" # nov # "/" # dec, year=1985, volume=67, number={1--3}, xxx-references={STOC::CookD82} } Author Index for Volume 67 -- page 223 Cumulative Subject Index for Volumes 64 -- 67 January/February/March 1986 Volume 68, Numbers 1-3 @Article{Poigne86, title={On Specifications, Theories, and Models with Higher Types}, author={Axel Poign{\'e}}, pages={1--46}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3} } @Article{LynchGFG86, title={Probabilistic Analysis of a Network Resource Allocation Algorithm}, author={Nancy A. Lynch and Nancy D. Griffeth and Michael J. Fischer and Leonidas J. Guibas}, pages={47--85}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, abstract={A distributed algorithm is presented, for allocating a large number of identical resources (such as airline tickets) to requests which can arrive anywhere in a distributed network. Resources, once allocated, are never returned. The algorithm searches sequentially, exhausting certain neighborhoods of the request origin before proceeding to search at greater distances. Choice of search direction is made non-deterministically. Analysis of expected response time is simplified by assuming that the search direction is chosen probabilistically, that messages require constant time, that the network is a tree with all leaves at the same distance from the root, and that requests and resources occur only at leaves. It is shown that the response time is approximated by the number of messages of one type that are sent during the execution of the algorithm, and that this number of messages is a nondecreasing function of the interarrival time for requests. Therefore, the worst case occurs when requests come in so far apart that they are processed sequentially. The expected time for the sequential case of the algorithm is analyzed by standard techniques. This time is shown to be bounded by a constant, independent of the size of the network. It follows that the expected response time for the algorithm is bounded in the same way.}, xxx-references={FischerGGL92} } @Article{Immerman86, title={Relational Queries Computable in Polynomial Time}, author={Neil Immerman}, pages={86--104}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, abstract={We characterize the polynomial time computable queries as those expressible in relational calculus plus a least fixed point operator and a total ordering on the universe. We also show that even without the ordering one application of fixed point suffices to express any query expressible with several alternations of fixed point and negation. This proves that the fixed point query hierarchy suggested by Chandra and Harel collapses at the first fixed point level. It is also a general result showing that in finite model theory one application of fixed point suffices.}, references={BOOK::AhoHU1974, POPL::AhoU1979, POPL::Chandra1981, JCSS::ChandraH1980, FOCS::ChandraH1980:333, MISC::Codd1972, STOC::Rougemont1984:409, BOOK::Enderton1972, SIAMAMSP::Fagin1974, FOCS::FurstSS1981:260, FOCS::GurevichS1985, JCSS::Immerman1981, JCSS::Immerman1982, STOC::Immerman1982:147, STOC::Immerman1983:347, BOOK::Moschovakis1974, STOC::Sipser1983:61, BOOK::Ullman1982, STOC::Vardi1982:137}, preliminary={stoc::Immerman1982} } @Article{ChazelleCPY86, title={New Upper Bounds for Neighbor Searching}, author={B. Chazelle and R. Cole and F. P. Preparata and C. Yap}, pages={105--124}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={FOCS::Chazelle83} } @Article{GrafS86a, title={A Modal Characterization of Observational Congruence on Finite Terms of {CCS}}, author={S. Graf and J. Sifakis}, pages={125--145}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, abstract={We propose a translation method for finite terms of \textbf{CCS} into formulas of a modal language representing their class of observational congruence. For this purpose, we define a modal language and a function associating with any finite term of CCS a formula of the language, satisfied by the term. Furthermore, this function is such that two terms are congruent if and only if the corresponding formulas are equivalent. The translation method consists in associating with operations on terms (that is action and +) operations on the corresponding formulas. This works is a first step towards the definition of a modal language with modalities expressing both possibility and inevitability that is compatible with observational congruence.}, references={ICALP::BrookesR1983, ICALP::HennessyM1980, TCS::Kozen1983, BOOK::Milner1980, TCS::Stirling985, THESIS::Graf1984, MISC::GrafS1985} } @Article{Townsend86, title={A Polynomial Jump Operator}, author={Mike Townsend}, pages={146--169}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={JACM::Ladner75, FOCS::Mahaney80, FOCS::Mehlhorn73, FOCS::Yao85} } @Article{HoffmanMRT86, title={Sorting {Jordan} Sequences in Linear Time Using Level-Linked Search Trees}, author={Kurt Hoffman and Kurt Mehlhorn and Pierre Rosenstiehl and Robert E. Tarjan}, pages={170--184}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={JACM::HopcroftT74, JACM::SleatorT85} } @Article{Brandt86, title={The Position of Index Sets of Identifiable Sets in the Arithmetical Hierarchy}, author={Ulrike Brandt}, pages={185--195}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={BlumB75, Gold67} } @Article{Huynh86, title={A Superexponential Lower Bound for {Gr\"obner} Bases and {Church}-{Rosser} Commutative {Thue} Systems}, author={Dung T. Huynh}, pages={196--206}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={STOC::CardozaLM76} } @Article{Flanagan86, title={An Optimally Data Efficient Isomorphism Inference Algorithm}, author={Peter A. Flanagan}, pages={207--222}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={BlumB75, Feldman72, Gold67, Gold78, Kugel77, Solomonoff64a, Solomonoff64b} } @Article{AptD86, title={Syntax Directed Analysis of Liveness Properties}, author={Krzysztof R. Apt and Carole Delporte-Gallet}, pages={223--253}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, xxx-references={STOC::BarringerKP84, STOC::Gerth84, FOCS::Pnueli77} } @Article{GrafS86b, title={A Logic for the Description of Non-deterministic Programs and Their Properties}, author={S. Graf and J. Sifakis}, pages={254--270}, journal=iandc, month=jan # "/" # feb # "/" # mar, year=1986, volume=68, number={1--3}, abstract={We present a logic, called \emph{Synchronization tree logic} (\textbf{STL}), for the specification and proof of programs described in a simple term language obtained from a constant \emph{Nil} by using a set $A$ of unary operators, a binary operator~$+$ and \emph{recursion}. The elements of \textbf{A} represent names of actions, $+$ represents non-deterministic choice, and \emph{Nil} is the program performing no action. The language of formulas of the logic proposed contains the term language used for the description of programs, i.e., programs are formulas of the logic. This provides a uniform frame to deal with programs and their properties as the verification of an assertion $t\models f$ ($t$ is a program and $f$ a formula) is reduced to the proof of the validity of the formula $t\supset f$. We propose a sound, and under some conditions complete deductive system for STL and discuss its relation with modal logics used for the specification of programs.}, references={ACTAI::Ben-AriPM1983, ICALP::BrookesR1983, JACM::HennessyM1985:137, TCS::Kozen1983, BOOK::Milner1980, ACTAI::QueilleS1983:195, THESIS::Graf1984, IC::GrafS1986:125, MISC::GrafS1985} } Author Index for Volume 68 -- page 271 April/May/June 1986 Volume 69, Numbers 1-3 @Article{HomerR86, title={Arithmetic Theories for Computational Complexity Problems}, author={Steve Homer and John Reif}, pages={1--11}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{DaleyS86, title={On the Complexity of Inductive Inference}, author={Robert P. Daley and Carl H. Smith}, pages={12--40}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3}, abstract={The notion of the complexity of performing an inductive inference is defined. Some examples of the tradeoffs between the complexity of performing an inference and the accuracy of the inferred result are presented. An axiomatization of the notion of the complexity of inductive inference is developed and several results are presented which both resemble and contrast with results obtainable for the axiomatic computational complexity of recursive functions.}, xxx-references={Angluin78, BlumB75, JACM::Blum67, Gold67, Gold78} } @Article{File86, title={Machines for Attribute Grammars}, author={Gilberto Fil{\'e}}, pages={41--124}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{ZachosH86, title={A Decisive Characterization of {BPP}}, author={Stathis Zachos and Hans Heller}, pages={125--135}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{RozenbergW86, title={Boundary {NLC} Graph Grammars---Basic Definitions, Normal Forms, and Complexity}, author={Grzegorz Rozenberg and Emo Welzl}, pages={136--167}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{AtallahH86, title={Solving Tree Problems on a Mesh-Connected Processor Array}, author={Mikhail J. Atallah and Susanne E. Hambrusch}, pages={168--187}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{Curien86, title={Categorical Combinators}, author={P.-L. Curien}, pages={188--254}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } @Article{Seiferas86, title={A Simplified Lower Bound for Context-Free-Language Recognition}, author={Joel I. Seiferas}, pages={255--260}, journal=iandc, month=apr # "/" # may # "/" # jun, year=1986, volume=69, number={1--3} } Author Index for Volume 69 -- page 261 July 1986 Volume 70, Number 1 @Article{AtzeniM86, title={Functional Dependencies and Constraints on Null Values in Database Relations}, author={Paolo Atzeni and Nicola M. Morfuni}, pages={1--31}, journal=iandc, month=jul, year=1986, volume=70, number=1 } @Article{ColeV86, title={Deterministic Coin Tossing with Applications to Optimal Parallel List Ranking}, author={Richard Cole and Uzi Vishkin}, pages={32--53}, journal=iandc, month=jul, year=1986, volume=70, number=1 } @Article{OrponenS86, title={The Density and Complexity of Polynomial Cores for Intractable}, author={Pekka Orponen and Uwe Sch{\"o}ning}, pages={54--68}, journal=iandc, month=jul, year=1986, volume=70, number=1 } @Article{OshersonSW86, title={Aggregating Inductive Expertise}, author={Daniel N. Osherson and Michael Stob and Scott Weinstein}, pages={69--95}, journal=iandc, month=jul, year=1986, volume=70, number=1 } August/September 1986 Volume 70, Numbers 2/3 @Article{HartS86, title={Probabilistic Propositional Temporal Logics}, author={Sergiu Hart and Micha Sharir}, pages={97--155}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3} } @Article{Royer86, title={Inductive Inference of Approximations}, author={James S. Royer}, pages={156--178}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3} } @Article{MoriyaIK86, title={A Note on some Simultaneous Relations among Time, Space, and Reversal for Single Work Tape Nondeterministic {Turing} Machines}, author={Etsuro Moriya and Shigeki Iwata and Takumi Kasai}, pages={179--185}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3} } @Article{Gacs86, title={Every Sequence Is Reducible to a Random One}, author={P{\'e}ter G{\'a}cs}, pages={186--192}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3} } @Article{LausenSW86, title={Pre-analysis Locking}, author={Georg Lausen and Eljas Soisalon-Soininen and Peter Widmayer}, pages={193--215}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3}, abstract={A safe and deadlock free locking policy is introduced, called pre-analysis locking. A transaction system with no lock and unlock operations in the transactions is first being analyzed by the pre-analysis locking algorithm. Then, the result of this analysis is used to insert lock and unlock operations into the transactions with the goal of achieving a degree of concurrency as high as possible. However, pre-analysis locking is merely a heuristic operating in polynomial time; therefore, it is not guaranteed to perform optimally in all cases. In comparison with two-phase locking, none of pre-analysis locking and two-phase locking dominates the other: there exist transaction systems in which pre-analysis locking allows for more concurrency than any two-phase locking policy, but there are also cases in which a two-phase locking policy allows for more concurrency than pre-analysis locking. However, pre-analysis locking is free from deadlocks, in general.}, references={ACTAI::BayerS1977, CACM::EswaranGLT1976, FOCS::KedemS1979, ICVLDB::KedemS1980, PODS::LausenSW1984:38, ICVLDB::LausenSW1985, JALGO::LipskiP1981:211, INFOS::OttmannSW1984, JACM::Papadimitriou1979:631, JACM::Papadimitriou1982, SICOMP::Papadimitriou1983, JACM::SilberschatzK1980, IEEETSE::SilberschatzK1982, SICOMP::Tarjan1972, BOOK::Ullman1982, MISC::Wolfson1984, STOC::Yannakakis1981, SICOMP::Yannakakis1982, JACM::Yannakakis1982, JACM::Yannakakis1984, FOCS::YannakakisPK1979} } @Article{DenenbergGS86, title={Definability by Constant-Depth Polynomial-Size Circuits}, author={Larry Denenberg and Yuri Gurevich and Saharon Shelah}, pages={216--240}, journal=iandc, month=aug # "/" # sep, year=1986, volume=70, number={2/3}, abstract={We investigate the expressive power of constant-depth polynomial-size circuit models. In particular, we construct a circuit model whose expressive power is precisely that of first-order logic.} } Author Index for Volume 70 -- page 241 October/November 1986 Volume 71, Numbers 1/2 @Article{DammG86, title={An Automata-Theoretical Characterization of the {OI}-Hierarchy}, author={Werner Damm and Andreas Goerdt}, pages={1--32}, journal=iandc, month=oct # "/" # nov, year=1986, volume=71, number={1/2} } @Article{Yokouchi86, title={Retraction Map Categories and Their Applications to the Construction of Lambda Calculus Models}, author={Hirofumi Yokouchi}, pages={33--86}, journal=iandc, month=oct # "/" # nov, year=1986, volume=71, number={1/2} } @Article{Zak86, title={An Exponential Lower Bound for Real-Time Branching Programs}, author={Stanislav {\v Z}{\'a}k}, pages={87--94}, journal=iandc, month=oct # "/" # nov, year=1986, volume=71, number={1/2} } @Article{MacQueenPS86, title={An Ideal Model for Recursive Polymorphic Types}, author={David MacQueen and Gordon Plotkin and Ravi Sethi}, pages={95--130}, journal=iandc, month=oct # "/" # nov, year=1986, volume=71, number={1/2} } @Article{KarpinskiV86, title={On the Power of Two-Way Random Generators and the Impossibility of Deterministic Poly-Space Simulation}, author={Marek Karpinski and Rutger Verbeek}, pages={131--142}, journal=iandc, month=oct # "/" # nov, year=1986, volume=71, number={1/2} } December 1986 Volume 71, Number 3 @Article{BodlaenderL86, author={H. L. Bodlaender and J. van Leeuwen}, title={Simulation of Large Networks on Smaller Networks}, pages={143--180}, journal=iandc, month=dec, year=1986, volume=71, number=3 } @Article{PapadimitriouY86, author={Christos H. Papadimitriou and Mihalis Yannakakis}, title={A Note on Succinct Representations of Graphs}, pages={181--185}, journal=iandc, month=dec, year=1986, volume=71, number=3 } @Article{MohanS86, title={Function Definitions in Term Rewriting and Applicative Programming}, author={Chilukuri K. Mohan and Mandayam K. Srivas}, pages={186--217}, journal=iandc, month=dec, year=1986, volume=71, number=3 } @Article{IiGS86, author={Culik II, K. and J. Gruska and A. Salomaa}, title={Systolic Trellis Automata: Stability, Decidability and Complexity}, pages={218--230}, journal=iandc, month=dec, year=1986, volume=71, number=3 } @Article{Heller86, title={On Relativized Exponential and Probabilistic Complexity Classes}, author={Hans Heller}, pages={231--243}, journal=iandc, month=dec, year=1986, volume=71, number=3 } Author Index for Volume 71 -- page 244 Cumulative Subject Index for Volumes 68-71 INFORMATION AND COMPUTATION January 1987 Volume 72, Number 1 @Article{Gunter87, title={Universal Profinite Domains}, author={Carl A. Gunter}, pages={1--30}, journal=iandcomp, month=jan, year=1987, volume=72, number=1 } @Article{AndrekaGN87, title={A Unifying Theorem for Algebraic Semantics and Dynamic Logics}, author={H. Andr{\'e}ka and I. Guessarian and I. N{\'e}meti}, pages={31--45}, journal=iandcomp, month=jan, year=1987, volume=72, number=1 } @Article{Thatte87, title={A Refinement of Strong Sequentiality for Term Rewriting with Constructors}, author={Satish Thatte}, pages={46--65}, journal=iandcomp, month=jan, year=1987, volume=72, number=1 } @Article{AmirG87, title={Preservation of Expressive Completeness in Temporal Models}, author={Amihood Amir and Dov M. Gabbay}, pages={66--83}, journal=iandcomp, month=jan, year=1987, volume=72, number=1 } February 1987 Volume 72, Number 2 @Article{CoppoDM87, title={Type Theories, Normal Forms and {${\rm D}_\infty$}-Lambda-Models}, author={M. Coppo and M. Dezani-Ciancaglini and M. Zacchi}, pages={85--116}, journal=iandcomp, month=feb, year=1987, volume=72, number=2 } @Article{DriscollF87, title={Computing Short Generator Sequences}, author={James R. Driscoll and Merrick L. Furst}, pages={117--132}, journal=iandcomp, month=feb, year=1987, volume=72, number=2 } @Article{Kutylowski87, title={A Generalized {Grzegorczyk} Hierarchy and Low Complexity Classes}, author={Miroslaw Kuty{\l}owski}, pages={133--149}, journal=iandcomp, month=feb, year=1987, volume=72, number=2 } @Article{RawlinsW87, title={Optimal Computation of Finitely Oriented Convex Hulls}, author={Gregory J. E. Rawlins and Derick Wood}, pages={150--166}, journal=iandcomp, month=feb, year=1987, volume=72, number=2 } March 1987 Volume 72, Number 3 @Article{Woll87, title={Reductions among Number Theoretic Problems}, author={Heather Woll}, pages={167--179}, journal=iandcomp, month=mar, year=1987, volume=72, number=3 } @Article{DolevHSS87, title={A New Look at Fault-Tolerant Network Routing}, author={Danny Dolev and Joseph Y. Halpern and Barbara Simons and H. Raymond Strong}, pages={180--196}, journal=iandcomp, month=mar, year=1987, volume=72, number=3, abstract={We model a communication network as a graph in which a processor is a node and a communication link is an edge. A routing for such a network is a fixed path, or route, between each pair of nodes. Given a network with a predefined routing, we study the effects of faulty components on the routing. Of particular interest is the number of routes along which a message must travel between any two non-faulty nodes. This problem is analyzed for specific families of graphs and for classes of routings. We also give some bounds for general versions of the problem. Finally, we conclude with one of the most important contributions of this paper, a list of interesting and apparently difficult open problems.} } @Article{Winskel87, title={Petri Nets, Algebras, Morphisms, and Compositionality}, author={Glynn Winskel}, pages={197--238}, journal=iandcomp, month=mar, year=1987, volume=72, number=3 } @Article{Kazakos87, title={Qualitative Robustness in Time Series}, author={P. Papantoni-Kazakos}, pages={239--269}, journal=iandcomp, month=mar, year=1987, volume=72, number=3 } @Article{MehlhornP87, title={Area-Time Optimal Division for {$T=\Omega((\log n)^{1+ \epsilon})$}}, author={K. Mehlhorn and F. P. Preparata}, pages={270--282}, journal=iandcomp, month=mar, year=1987, volume=72, number=3 } Author Index for Volume 72 -- page 283 April 1987 Volume 73, Number 1 @Article{DurisGS87, title={Lower Bounds on Communication Complexity}, author={Pavol Duris and Zvi Galil and Georg Schnitger}, pages={1--22}, journal=iandcomp, month=apr, year=1987, volume=73, number=1 } @Article{TeneketzisH87, title={The Decentralized {Wald} Problem}, author={Demosthenis Teneketzis and Yu-Chi Ho}, pages={23--44}, journal=iandcomp, month=apr, year=1987, volume=73, number=1 } @Article{BeckerO87, title={Layouts with Wires of Balanced Length}, author={B. Becker and H. G. Osthof}, pages={45--59}, journal=iandcomp, month=apr, year=1987, volume=73, number=1 } @Article{ClerboutL87, title={Semi-commutations}, author={M. Clerbout and M. Latteux}, pages={59--74}, journal=iandcomp, month=apr, year=1987, volume=73, number=1 } @Article{Rytter87, title={Parallel Time {$O(\log n)$} Recognition of Unambiguous Context-free Languages}, author={Wojciech Rytter}, pages={75--86}, journal=iandcomp, month=apr, year=1987, volume=73, number=1 } May 1987 Volume 73, Number 2 @Article{PaciniT87, title={Semantics of Production Systems}, author={Giuliano Pacini and Franco Turini}, pages={87--101}, journal=iandcomp, month=may, year=1987, volume=73, number=2 } @Article{LiY87, title={Separation and Lower Bounds for {ROM} and Nondeterministic Models of Parallel Computation}, author={Ming Li and Yaacov Yesha}, pages={102--128}, journal=iandcomp, month=may, year=1987, volume=73, number=2 } @Article{Obtulowicz87, title={Algebra of Constructions. {I}. The Word Problem for Partial Algebras}, author={Adam Obtu{\l}owicz}, pages={129--173}, journal=iandcomp, month=may, year=1987, volume=73, number=2 } @Article{GinsburgG87, title={Object Histories Which Avoid Certain Subsequences}, author={Seymour Ginsburg and Marc Gyssens}, pages={174--206}, journal=iandcomp, month=may, year=1987, volume=73, number=2 } June 1987 Volume 73, Number 3 @Article{CostaS87, title={Weak and Strong Fairness in {CCS}}, author={Berardo Costa and Colin Stirling}, pages={207--244}, journal=iandcomp, month=jun, year=1987, volume=73, number=3 } @Article{EngelfrietV87, title={Look-Ahead on Pushdowns}, author={Joost Engelfriet and Heiko Vogler}, pages={245--279}, journal=iandcomp, month=jun, year=1987, volume=73, number=3 } Author Index for Volume 73 -- page 280 July 1987 Volume 74, Number 1 @Article{Krichevsky87, title={Information Compression and {Varshamov}-{Gilbert} Bound}, author={R. E. Krichevsky}, pages={1--14}, journal=iandcomp, month=jul, year=1987, volume=74, number=1 } @Article{KirschenhoferP87, author={Peter Kirschenhofer and Helmut Prodinger}, title={On the Recursive Depth of Special Tree Traversal Algorithms}, pages={15--32}, journal=iandcomp, month=jul, year=1987, volume=74, number=1 } @Article{PelegS87, title={On Fault Tolerant Routings in General Networks}, author={David Peleg and Barbara Simons}, pages={33--49}, journal=iandcomp, month=jul, year=1987, volume=74, number=1 } @Article{YangM87, title={An Efficient Algorithm for Multiprocessor Fault Diagnosis Using the Comparison Approach}, author={Che-Liang Yang and Gerald M. Masson}, pages={50--63}, journal=iandcomp, month=jul, year=1987, volume=74, number=1 } @Article{Rozoy87, title={The {Dyck} Language {$D'_1{}^{*}$} Is Not Generated by Any Matric Grammar of Finite Index}, author={Brigitte Rozoy}, pages={64--89}, journal=iandcomp, month=jul, year=1987, volume=74, number=1 } August 1987 Volume 74, Number 2 @Article{MarronK87, title={Identification of Pattern Languages from Examples and Queries}, author={Assaf Marron and Ker-I Ko}, pages={91--112}, journal=iandcomp, month=aug, year=1987, volume=74, number=2 } @Article{FredericksonS87, title={On-line Updating of Solutions to a Class of Matroid Intersection Problems}, author={Greg N. Frederickson and Mandayam A. Srinivas}, pages={113--139}, journal=iandcomp, month=aug, year=1987, volume=74, number=2, abstract={The class of matroid intersection problems is considered in which one of the matroids is a partition matroid specifying that exactly $q$ elements in the solution must be red, and the rest green. A characterization is presented for how the solution changes when one element changes in cost. Data structures are given for updating the solution on-line each time the cost of an arbitrary matroid element is modified. Efficient update algorithms are given for maintaining a red-green minimum spanning tree in both a general and a planar graph, and a red-green job schedule for unit-time jobs with deadlines.} } @Article{Kratsch87, title={Finding the Minimum Bandwidth of an Interval Graphs}, author={Dieter Kratsch}, pages={140--158}, journal=iandcomp, month=aug, year=1987, volume=74, number=2 } @Article{Welch87, title={Simulating Synchronous Processors}, author={Jennifer Lundelius Welch}, pages={159--170}, journal=iandcomp, month=aug, year=1987, volume=74, number=2 } September 1987 Volume 74, Number 3 @Article{Sakarovitch87, title={Easy Multiplications. {I}. {The} Realm of {Kleene's} Theorem}, author={Jacques Sakarovitch}, pages={173--197}, journal=iandcomp, month=sep, year=1987, volume=74, number=3 } @Article{Hrbacek87, title={Convex Powerdomains {I}}, author={Karel Hrbacek}, pages={198--225}, journal=iandcomp, month=sep, year=1987, volume=74, number=3 } @Article{BoppanaL87, title={One-Way Functions and Circuit Complexity}, author={R. B. Boppana and J. C. Lagarias}, pages={226--240}, journal=iandcomp, month=sep, year=1987, volume=74, number=3 } @Article{Santha87, title={On Using Deterministic Functions to Reduce Randomness in Probabilistic Algorithms}, author={Miklos Santha}, pages={241--249}, journal=iandcomp, month=sep, year=1987, volume=74, number=3 } Author Index for Volume 74 -- page 252 October 1987 Volume 75, Number 1 @Article{Carlson87, title={Time-Space Efficient Algorithms for Computing Convolutions and Related Problems}, author={David A. Carlson}, pages={1--14}, journal=iandcomp, month=oct, year=1987, volume=75, number=1 } @Article{HeY87, title={Parallel Recognitions and Decomposition of Two Terminal Series Parallel Graphs}, author={Xin He and Yaacov Yesha}, pages={15--38}, journal=iandcomp, month=oct, year=1987, volume=75, number=1 } @Article{Hagerup87, title={Towards Optimal Parallel Bucket Sorting}, author={Torben Hagerup}, pages={39--51}, journal=iandcomp, month=oct, year=1987, volume=75, number=1, abstract={We present a simple deterministic parallel algorithm that runs on a CRCW PRAM and sorts $n$ integers of size polynomial in $n$ in time $O(\log n)$ using $O(n \log \log n/\log n)$ processors. It is cloer to optimality than any previously known deterministic algorithm that solves the stated restricted problem in polylog time.}, xxx-references={STOC::AjtaiKS83, FOCS::Cole86, ColeV86, FOCS::ColeV86, ColeV89, STOC::FichHRW85, JACM::Goldschlager82, STOC::Leighton84, FOCS::Reif85} } @Article{BroderDFS87, title={Efficient Fault-Tolerant Routings in Networks}, author={Andrei Broder and Danny Dolev and Michael Fischer and Barbara Simons}, pages={52--64}, journal=iandcomp, month=oct, year=1987, volume=75, number=1 } @Article{WanerW87, title={The Hierarchical Structure of Graph Searches}, author={Stefan Waner and Yihren Wu}, pages={65--85}, journal=iandcomp, month=oct, year=1987, volume=75, number=1 } November 1987 Volume 75, Number 2 @Article{Angluin87, author={Dana Angluin}, title={Learning Regular Sets from Queries and Counterexamples}, pages={87--106}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } @Article{KleinW87, author={Rolf Klein and Derick Wood}, title={The Node Visit Cost of Brother Trees}, pages={107--129}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } @Article{Bracha87, author={Gabriel Bracha}, title={Asynchronous {Byzantine} Agreement Protocols}, pages={130--143}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } @Article{YamamotoN87, author={Hiroaki Yamamoto and Shoichi Noguchi}, title={Comparison of the Power between Reversal-Bounded {ATM}s and Reversal-Bounded {NTM}s}, pages={144--161}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } @Article{MansourZ87, author={Y. Mansour and S. Zaks}, title={On the Bit Complexity of Distributed Computations in a Ring with a Leader}, pages={162--177}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } @Article{KarpinskiV87, author={Marek Karpinski and Rutger Verbeek}, title={On the {Monte} {Carlo} Space Constructible Functions and Seperation Results for Probabilistic Complexity Classes}, pages={178--189}, journal=iandcomp, month=nov, year=1987, volume=75, number=2 } December 1987 Volume 75, Number 3 @Article{BarendregtKKS87, oldkey={KennawaySBK87}, author={H. P. Barendregt and J. R. Kennaway and J. W. Klop and M. R. Sleep}, title={Needed Reduction and Spine Strategies for the Lambda Calculus}, pages={191--231}, journal=iandcomp, month=dec, year=1987, volume=75, number=3, abstract={A redex $R$ in a lambda-term $M$ is called {\em needed\/} if in every reduction of $M$ to normal form (some residual of) $R$ is contracted. Among others the following results are proved: 1.~$R$ is needed in $M$ iff $R$ is contracted in the leftmost reduction path of $M$. 2.~Let ${\cal R} : M_0 \rightarrow M_1 \rightarrow M_2 \rightarrow \dots$ reduce redexes $R_i: M_i \rightarrow M_{i+1}$, and have the property that $\forall i.\exists j \ge i.R_j$ is needed in $M_j$. Then ${\cal R}$ is normalising, i.e.~if $M_0$ has a normal form, then ${\cal R}$ is finite and terminates at that normal form. 3.~Neededness is an undecidable property, but has several efficiently decidable approximations, various versions of the so called {\em spine\/} redexes.}, references={LFP::Augustsson1984:218, MISC::Barendregt1977:209, BOOK::Barendregt1984, CIP::Berry1978, JACM::BerryL1979:148, SCP::BurnHA1986:249, LISP::BurstallMS1981:136, TR::EekelenP1985, MISC::GordonMW1979, TR::HuetL1979, Kennaway1987, CWI::Klop1980, COMPJ::Landin1964:308, CACM::Landin1966:157, LCCST::Levy1975:147, MISC::Levy1980, BOOK::McCarthyAEHL1962, THESIS::Mycroft1981, SPE::Turner1979:31, FPLCA::Turner1985:1, THESIS::Wadsworth1971} } @Article{HauschildtV87, author={Dirk Hauschildt and R{\"u}diger Valk}, title={Safe States in Banker-like Resource Allocations Problems}, pages={232--263}, journal=iandcomp, month=dec, year=1987, volume=75, number=3 } @Article{Kranakis87, author={Evangelos Kranakis}, title={Fixed Point Equations with Parameters in the Projective Model}, pages={264--288}, journal=iandcomp, month=dec, year=1987, volume=75, number=3, abstract={Existence and uniqueness theorems are given for solving infinite and finite systems of fixed point equations with parameters in the projective model (a natural model in the calculus of communicating processes). The results obtained are derived by exploiting the special topological and combinatorial properties of the projective model and the polynomial operators defined on it. The topological methods employed in the proofs of the existence and uniqueness theorems use a combination of the following three ideas: compactness argument, density argument, and Banach's contraction principle. As a converse to the uniqueness theorem it is also shown, using combinatorial methods, that in certain signatures guarded equations are the only ones that have unique fixed points.} } @Article{RoscoeD87, author={A. W. Roscoe and Naiem Dathi}, title={The Pursuit of Deadlock freedom}, pages={289--327}, journal=iandcomp, month=dec, year=1987, volume=75, number=3 } Author Index for Volume 75 -- page 328 Cumulative Subject Index for Volumes 72-75 -- pages 329-332 January 1988 Volume 76, Number 1 @Article{Spirakis88, author={Paul G. Spirakis}, title={Optimal Parallel Randomized Algorithms for Addition Sparse Addition and Identification}, pages={1--12}, journal=iandcomp, month=jan, year=1988, volume=76, number=1 } @Article{Beame88, author={Paul Beame}, title={Limits on the Power of Concurrent-Write Parallel Machines}, pages={13--28}, journal=iandcomp, month=jan, year=1988, volume=76, number=1 } @Article{Nielson88, author={Flemming Nielson}, title={Strictness Analysis and Denotational Abstract Interpretation}, pages={29--92}, journal=iandcomp, month=jan, year=1988, volume=76, number=1 } February/March 1988 Volume 76, Numbers 2/3 Special Issue Semantics of Data Types Gordon D. Plotkin, Special Issue Editor @Article{Plotkin88, title={Preface}, author={G. D. Plotkin}, pages={93}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3} } @Article{CoquandH88, title={The Calculus of Constructions}, author={Thierry Coquand and G{\'e}rard Huet}, pages={95--120}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3}, xxx-references={BarendregtR83} } @Article{Padawitz88, title={The Equational Theory of Parameterized Specifications}, author={Peter Padawitz}, pages={121--137}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3} } @Article{Cardelli88, title={A Semantics of Multiple Inheritance}, author={Luca Cardelli}, pages={138--164}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3}, xxx-references={MacQueenPS86} } @Article{SannellaT88, title={Specifications in an Arbitrary Institution}, author={Donald Sannella and Andrzej Tarlecki}, pages={165--210}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3}, abstract={A formalism for constructing and using axiomatic specifications in an arbitrary logical system is presented. This builds on the framework provided by Goguen and Burstall's work on the notion of an institution as a formalisation of the concept of a logical system for writing specifications. We show how to introduce free variables into the sentences of an arbitrary institution and how to add quantifiers which bind them. We use this foundation to define a set of primitive operations for building specifications in an arbitrary institution based loosely on those in the ASL kernel specification language. We examine the set of operations which results when the definitions are instantiated in institutions of total and partial first-order logic and compare these with the operations found in existing specification languages. We present proof rules which allow proofs to be conducted in specifications built using the operations we define. Finally, we introduce a simple mechanism for defining and applying parameterised specifications and briefly discuss the program development process.} } @Article{Mitchell88, title={Polymorphic Type Inference and Containment}, author={John C. Mitchell}, pages={211--249}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3}, xxx-references={BruceMM90, MacQueenPS86, Meyer82} } @Article{Moggi88, title={Partial Morphisms in Categories of Effective Objects}, author={Eugenio Moggi}, pages={250--277}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3} } @Article{LampsonB88, title={Pebble, a Kernel Language for Modules and Abstract Data Types}, author={B. Lampson and R. Burstall}, pages={278--346}, journal=iandcomp, month=feb # "/" # mar, year=1988, volume=76, number={2/3} } Author Index for Volume 76 -- page 347 April 1988 Volume 77, Number 1 @Article{WelchL88, author={Jennifer Lundelius Welch and Nancy A. Lynch}, title={A New Fault-Tolerance Algorithm for Clock Synchronization}, pages={1--36}, journal=iandcomp, month=apr, year=1988, volume=77, number=1, abstract={We describe a new fault-tolerant algorithm for solving a variant of Lamport's clock synchronization problem. The algorithm is designed for a system of distributed processes that communicate by sending messages. Each process has its own read-only physical clock whose drift rate from real time is very small. By adding a value to its physical clock time, the process obtains its local time. The algorithm solves the problem of maintaining closely synchronized local times, assuming that processes' local times are closely synchronized initially. The algorithm is able to tolerate the failure of just under one-third of the participating processes. It maintains synchronization to within a small constant, whose magnitude depends upon the rate of clock drift, the message delivery time and its uncertainty, and the initial closeness of synchronization. We also give a characterization of how far the clocks drift from real time. Reintegration of a repaired process can be accomplished using a slight modification of the basic algorithm. A similar style algorithm can also be used to achieve synchronization initially.} } @Article{AmirG88, author={Amihood Amir and William I. Gasarch}, title={Polynomial Terse Sets}, pages={37--56}, journal=iandcomp, month=apr, year=1988, volume=77, number=1, abstract={Let $A$ be a set and $k\in N$ be such that we wish to know the answers to $x_1\in A$?, $x_2\in A$?, $\ldots$, $x_k\in A$? for various $k$-tuples $(x_1,x_2,\ldots,x_k)$. If this problem \emph{requires} $k$ queries to $A$ in order to be solved in polynomial time then $A$ is called \emph{polynomial terse} or \emph{pterse}. We show the existence of both arbitrarily complex pterse and non-pterse sets; and that \textbf{P$\ne$NP} iff every \textbf{NP}-complete set is pterse. We also show connections with p-immunity, p-selective, p-generic sets, and the boolean hierarchy. In our framework \textbf{Unique Satisfiability} (and a variation of it called kSAT) is, in some sense, ``close" to \textbf{Satisfiability}.}, xxx-references={BlassG82, Selman82} } @Article{Stanfel88, author={Larry E. Stanfel}, title={Mathematical Optimization and the Synchronizing Properties of Encodings}, pages={57--76}, journal=iandcomp, month=apr, year=1988, volume=77, number=1, xxx-references={Schwartz64, Stanfel69} } @Article{PittS88, author={Leonard Pitt and Carl H. Smith}, title={Probability and Plurality for Aggregations of Learning Machines}, pages={77--92}, journal=iandcomp, month=apr, year=1988, volume=77, number=1, abstract={A new notion of probabilistic team inductive inference is introduced and compared with both probabilistic inference and team inference. In many cases, but not all, probabilism can be traded for pluralism, and vice versa. Necessary and sufficient conditions are given describing when a team of deterministic or probabilistic learning machines can be coalesced into a single learning machine. A subtle difference between probabilism and pluralism is revealed.}, xxx-references={BlumB75, Feldman72, Gold67, OshersonSW86} } May 1988 Volume 77, Number 2 @Article{SlotB88, author={Cees Slot and Peter {van Emde Boas}}, title={The Problem of Space Invariance for Sequential Machines}, pages={93--122}, journal=iandcomp, month=may, year=1988, volume=77, number=2, xxx-references={Davis82} } @Article{BagchiS88, author={Bhaskar Bagchi and N. S. Narasimha Sastry}, title={One-Step Completely Orthogonalizable Codes from Generalized Quadrangles}, pages={123--130}, journal=iandcomp, month=may, year=1988, volume=77, number=2, xxx-references={Delsarte71} } @Article{Dekkers88, author={Wil Dekkers}, title={Reducibility of Types in Typed Lambda Calculus: Comment on a Paper by {Richard} {Statman}}, pages={131--137}, journal=iandcomp, month=may, year=1988, volume=77, number=2 } @Article{OshersonSW88, author={Daniel N. Osherson and Michael Stob and Scott Weinstein}, title={Synthesizing Inductive Expertise}, pages={138--161}, journal=iandcomp, month=may, year=1988, volume=77, number=2, xxx-references={Angluin80, BlumB75, Gold67} } @Article{BeckerS88, author={Bernd Becker and Hans-Ulrich Simon}, title={How Robust Is The $n$-Cube?}, pages={162--178}, journal=iandcomp, month=may, year=1988, volume=77, number=2 } June 1988 Volume 77, Number 3 @Article{Westerdale88, author={T. H. Westerdale}, title={An Automaton Decomposition for Learning System Environments}, pages={179--191}, journal=iandcomp, month=jun, year=1988, volume=77, number=3 } @Article{Cosmadakis88, author={Stavros Cosmadakis}, title={The Word and Generator Problems for Lattices}, pages={192--217}, journal=iandcomp, month=jun, year=1988, volume=77, number=3 } @Article{EdelsbrunnerP88, author={H. Edelsbrunner and F. P. Preparata}, title={Minimum Polygonal Separation}, pages={218--232}, journal=iandcomp, month=jun, year=1988, volume=77, number=3 } @Article{Frougny88, author={Christiane Frougny}, title={Linear Numeration Systems of Order Two}, pages={233--259}, journal=iandcomp, month=jun, year=1988, volume=77, number=3, xxx-references={Sakarovitch87} } Author Index for Volume 77 -- page 260 July 1988 Volume 78, Number 1 @Article{CourcelleD88, author={B. Courcelle and P. Deransart}, title={Proofs of Partial Correctness for Attribute Grammars with Applications to Recursive Procedures and Logic Programming}, pages={1--55}, journal=iandcomp, month=jul, year=1988, volume=78, number=1, xxx-references={DuskePSS77} } @Article{LiV88, author={Ming Li and Paul M. B. Vit{\'a}nyi}, title={Tape versus Queue and Stacks: The Lower Bounds}, pages={56--85}, journal=iandcomp, month=jul, year=1988, volume=78, number=1, abstract={Several optimal or nearly optimal lower bounds are derived on the time needed to simulate queue, stacks (stack = pushdown store) and tapes by one off-line single-head tape-unit with one-way input, for both the deterministic case and the nondeterministic case. The techniques rely on algorithmic information theory (Kolmogorov complexity).}, xxx-references={DurisGPR84, Solomonoff64a} } August 1988 Volume 78, Number 2 @Article{Selman88, author={Alan L. Selman}, title={Promise Problems Complete for Complexity Classes}, pages={87--97}, journal=iandcomp, month=aug, year=1988, volume=78, number=2, abstract={A general framework is given to obtain hardness results for promise problems that derive from self-reducible decision problems. The principal theorem is that if a set $A$ is $\leq_d^{\rm P}$-equivalent to a disjunctive-self-reducible set in NP, then the natural promise problem associated with $A$ is as hard to solve as it is to recognize $A$. NP-hardness of the Satisfiability promise problem follows, and graph isomorphism hardness of a promise problem that derives from the graph isomorphism problem is proved.}, references={JCSS::Book1974, IC::EvenY1984:159, ICALP::EvenY1980, BOOK::GareyJ1979, COMB::LovaszGS1981, FOCS::GrollmannS1984:495, BOOK::HopcroftU1979, JACM::Hunt1984:299, JCSS::Ko1983, TCS::LadnerLS1975:103, TR::MeyerP1979, ICALP::Schnorr1976, MST::Selman1979, IC::Selman1982:36, TCS::Selman1982, TR::Selman1986, TCS::Stockmeyer1976, ICALP::SelmanY1982, STOC::ValiantV1985:458} } @Article{BabaiJH88, oldkey={BabaiJM88}, author={L{\'a}szl{\'o} Babai and Bettina Just and Friedhelm {Meyer auf der Heide}}, title={On the Limits of Computations with the Floor Function}, pages={99--107}, journal=iandcomp, month=aug, year=1988, volume=78, number=2 } @Article{Compton88, author={Kevin J. Compton}, title={The Computational Complexity of Asymptotic Problems {I}: Partial Orders}, pages={108--123}, journal=iandcomp, month=aug, year=1988, volume=78, number=2, xxx-references={BlassGK85, Grandjean83, Immerman86} } @Article{Hashiguchi88, author={Kosaburo Hashiguchi}, title={Algorithms for Determining Relative Star Height and Star Height}, pages={124--169}, journal=iandcomp, month=aug, year=1988, volume=78, number=2, xxx-references={DejeanS66, Hashiguchi82, HashiguchiH76, McNaughton66} } September 1988 Volume 78, Number 3 @Article{ItohT88, author={Toshiya Itoh and Shigeo Tsujii}, title={A Fast Algorithm for Computing Multiplicative Inverses in {GF($2^{m}$)} Using Normal Bases}, pages={171--177}, journal=iandcomp, month=sep, year=1988, volume=78, number=3 } @Article{EphremidisPS88, author={Sophocles Ephremidis and Christos H. Papadimitriou and Martha Sideris}, title={Complexity Characterizations of Attribute Grammar Languages}, pages={178--186}, journal=iandcomp, month=sep, year=1988, volume=78, number=3 } @Article{Vogler88, author={Heiko Vogler}, title={The {OI}-Hierarchy Is Closed under Control}, pages={187--204}, journal=iandcomp, month=sep, year=1988, volume=78, number=3, xxx-references={Asveld77, DammG86, GinsburgR75, Greibach70, Khabbaz74} } @Article{BaetenB88, author={J. C. M. Baeten and J. A. Bergstra}, title={Global Renaming Operators in Concrete Process Algebra}, pages={205--245}, journal=iandcomp, month=sep, year=1988, volume=78, number=3, abstract={Renaming operators are introduced in concrete process algebra (concrete means that abstraction and silent moves are not considered). Examples of renaming operators are given: encapsulation, pre-abstraction and localization. We show that renamings enhance the defining power of concrete process algebra by using the example of a queue. We give a definition of the trace set of a process, see when equality of trace sets implies equality of processes, and use trace sets to define the restriction of a process. Finally, we describe processes with actions that have a side effect on a state space and show how to use this for a translation of computer programs into process algebra.}, xxx-references={BakkerZ82, BergstraK84} } @Article{Landau88, author={Susan Landau}, title={Some Remarks on Computing the Square Parts of Integers}, pages={246--253}, journal=iandcomp, month=sep, year=1988, volume=78, number=3, xxx-references={Woll87} } Author Index for Volume 78 -- page 254 October 1988 Volume 79, Number 1 @Article{Gelder88, author={Allen Van Gelder}, title={A Satisfiability Tester for Non-clausal Propositional Calculus}, pages={1--21}, journal=iandcomp, month=oct, year=1988, volume=79, number=1 } @Article{Hortala-Gonzalezlm88, author={M. Teresa Hortal{\'a}-Gonz{\'a}lez and Francisca Lucio-Carrasco and Mario Rodr{\'\i}guez-Artalejo}, title={Some General Incompleteness Results for Partial Correctness Logics}, pages={22--42}, journal=iandcomp, month=oct, year=1988, volume=79, number=1, xxx-references={BergstraCT82} } @Article{ItaiR88, author={Alon Itai and Michael Rodeh}, title={The Multi-Tree Approach to Reliability in Distributed Networks}, pages={43--59}, journal=iandcomp, month=oct, year=1988, volume=79, number=1 } @Article{BensonB88, author={David B. Benson and Ofer Ben-Shachar}, title={Bisimulation of Automata}, pages={60--83}, journal=iandcomp, month=oct, year=1988, volume=79, number=1, xxx-references={BergstraK84, MainB84} } @Article{Beaudry88, author={Martin Beaudry}, title={Membership Testing in Commutative Transformation Semigroups}, pages={84--93}, journal=iandcomp, month=oct, year=1988, volume=79, number=1, abstract={The membership problem in transformation monoids is the natural extension to the well-studied membership problem in permutation groups. We consider the restriction of the problem to the varieties of threshold one monoids, those monoids in which every element $f$ satisfies $f^{p+1} = f$, for some integer $p$. We find that each of the complexity classes ${\it AC}^0$, {\it NC}, and {\it P} can be associated with a variety of threshold one monoids which, within the hypothesis that ${\it NC} \ne {\it P}$ and ${\it P} \ne {\it NP}$, is the unique largest variety of monoids where the membership problem can be done with this complexity. We extend our study to other cases of threshold one monoids, for which we obtain {\it NP}-completeness results. We also consider the problem which consists in deciding whether the transformation monoid of an automaton belongs to a specific variety: we show that we can do in ${\it AC}^0$ the characterization of monoids in three of the varieties most significant to our study of the membership problem.}, xxx-references={Cook85} } November 1988 Volume 79, Number 2 @Article{RobinsonR88, author={E. Robinson and G. Rosolini}, title={Categories of Partial Maps}, pages={95--130}, journal=iandcomp, month=nov, year=1988, volume=79, number=2 } @Article{RinatFG88, author={Ran Rinat and Nissim Francez and Orna Grumberg}, title={Infinite Trees, Markings and Well-Foundedness}, pages={131--154}, journal=iandcomp, month=nov, year=1988, volume=79, number=2, xxx-references={GrumbergFR85} } @Article{Stohr88, author={Elena St{\"o}hr}, title={A Trade-off between Page Number and Page Width of Book Embeddings of Graphs}, pages={155--162}, journal=iandcomp, month=nov, year=1988, volume=79, number=2 } @Article{TsaknakisP88, author={Haralampos Tsaknakis and P. Papantoni-Kazakos}, title={Outlier Resistent Filtering and Smoothing}, pages={163--192}, journal=iandcomp, month=nov, year=1988, volume=79, number=2, xxx-references={Kazakos87, Kazakos84} } December 1988 Volume 79, Number 3 @Article{Fulk88, author={Mark Fulk}, title={Saving the Phenomena: Requirements that Inductive Inference Machines Not Contradict Known Data}, pages={193--209}, journal=iandcomp, month=dec, year=1988, volume=79, number=3, xxx-references={BlumB75, Gold67} } @Article{KoymansSRGA88, oldkey={Arun-KumarKSR88}, author={R. Koymans and R. K. Shyamasundar and W. P. de Roever and R. Gerth and S. Arun-Kumar}, title={Compositional Semantics for Real-Time Distributed Computing}, pages={210--256}, journal=iandcomp, month=dec, year=1988, volume=79, number=3 } @Article{Trachtenberg88, author={E. A. Trachtenberg}, title={Fault Tolerant Computing and Reliable Communication: A Unified Approach}, pages={257--279}, journal=iandcomp, month=dec, year=1988, volume=79, number=3, xxx-references={KarpovskyT79} } Author Index for Volume 79 -- page 280 Cumulative Subject Index for Volumes 76-79 January 1989 Volume 80, Number 1 @Article{TorenvlietB89, author={Leen Torenvliet and Peter {van Emde Boas}}, title={Simplicity, Immunity, Relativizations and Nondeterminism}, pages={1--17}, journal=iandcomp, month=jan, year=1989, volume=80, number=1, xxx-references={GasarchH83} } @Article{BuningL89, author={Hans Kleine B{\"u}ning and Ulrich L{\"o}wen}, title={Optimizing Propositional Calculus Formulas with Regard to Questions of Deducibility}, pages={18--43}, journal=iandcomp, month=jan, year=1989, volume=80, number=1 } @Article{Santha89, author={Miklos Santha}, title={Relativized {Arthur}-{Merlin} versus {Merlin}-{Arthur} Games}, pages={44--49}, journal=iandcomp, month=jan, year=1989, volume=80, number=1 } @Article{CurienO89, author={P.-L. Curien and A. Obtu{\l}owicz}, title={Partiality, {Cartesian} closedness and Toposes}, pages={50--95}, journal=iandcomp, month=jan, year=1989, volume=80, number=1 } February 1989 Volume 80, Number 2 @Article{KlopV89, author={J. W. Klop And R. C. de Vrijer}, title={Unique Normal Forms for Lambda Calculus with Surjective Pairing}, pages={97--113}, journal=iandcomp, month=feb, year=1989, volume=80, number=2 } @Article{Engelfriet89, author={Joost Engelfriet}, title={The Power to Two-Way Deterministic Checking Stack Automata}, pages={114--120}, journal=iandcomp, month=feb, year=1989, volume=80, number=2, xxx-references={Greibach78a, IbarraKR85a} } @Article{Bernot89, author={Gilles Bernot}, title={Correctness Proofs for Abstract Implementation}, pages={121--151}, journal=iandcomp, month=feb, year=1989, volume=80, number=2 } @Article{Vazirani89, author={Vijay V. Vazirani}, title={{NC} Algorithms for Computing the Number of Perfect Matchings in {$K_{3,3}$}-Free Graphs and Related Problems}, pages={152--164}, journal=iandcomp, month=feb, year=1989, volume=80, number=2, xxx-references={BorodinCP83} } @Article{CousotC89, author={Patrick Cousot and Radhia Cousot}, title={A Language Independent Proof of the Soundness and Completeness of Generalized {Hoare} Logic}, pages={165--191}, journal=iandcomp, month=feb, year=1989, volume=80, number=2 } March 1989 Volume 80, Number 3 @Article{RuzzoK89, author={Howard J. Karloff and Walter L. Ruzzo}, title={The Iterated Mod Problem}, pages={193--204}, journal=iandcomp, month=mar, year=1989, volume=80, number=3, xxx-references={AndersonMW89, BorodinGH82, Cook85} } @Article{DymondC89, author={Patrick W. Dymond and Stephen A. Cook}, title={Complexity Theory of Parallel Time and Hardware}, pages={205--226}, journal=iandcomp, month=mar, year=1989, volume=80, number=3, xxx-references={Hong84} } @Article{RivestQ89, author={J. Ross Quinlan and Ronald L. Rivest}, title={Inferring Decision Trees Using the Minimum Description Length Principle}, pages={227--248}, journal=iandcomp, month=mar, year=1989, volume=80, number=3 } @Article{FrancezP89, author={Sara Porat and Nissim Francez}, title={Fairness in Context-Free Grammars under Every Choice-strategy}, pages={249--268}, journal=iandcomp, month=mar, year=1989, volume=80, number=3, xxx-references={ZaksFPM82} } @Article{LangeJK89, author={Birgit Jenner and Bernd Kirsig and Klaus-J{\"o}rn Lange}, title={The Logarithmic Alternation Hierarchy Collapses: {$\bf A \sum^{\cal{L}}_{2}={A}{\Pi}^{\cal{L}}_{2}$}}, pages={269--287}, journal=iandcomp, month=mar, year=1989, volume=80, number=3 } Author Index for Volume 80 -- page 289 April 1989 Volume 81, Number 1 @Article{Tiuryn89, author={Jerzy Tiuryn}, title={A Simplified Proof of {{\sl DDL $<$ DL}}}, pages={1--12}, journal=iandcomp, month=apr, year=1989, volume=81, number=1, xxx-references={Kfoury85, StolboushkinT83, Urzyczyn83b} } @Article{ClarkeGB89, author={M. C. Browne and E. M. Clarke and O. Grumberg}, title={Reasoning about Networks with Many Identical Finite State Processes}, pages={13--31}, journal=iandcomp, month=apr, year=1989, volume=81, number=1 } @Article{RytterG89, author={Alan Gibbons and Wojciech Rytter}, title={Optimal Parallel Algorithm for Dynamic Expression Evaluation and Context-Free Recognition}, pages={32--45}, journal=iandcomp, month=apr, year=1989, volume=81, number=1, xxx-references={Rytter87} } @Article{Fraenkel89, author={Aviezri S. Fraenkel}, title={The Use and Usefulness of Numeration Systems}, pages={46--61}, journal=iandcomp, month=apr, year=1989, volume=81, number=1 } @Article{Ko89, author={Ker-I Ko}, title={Distinguishing Conjunctive and Disjunctive Reducibilities by Sparse Sets}, pages={62--87}, journal=iandcomp, month=apr, year=1989, volume=81, number=1 } @Article{EngelfrietL89, author={Joost Engelfriet and George Leih}, title={Linear Graph Grammars: Power and Complexity}, pages={88--121}, journal=iandcomp, month=apr, year=1989, volume=81, number=1, xxx-references={RozenbergW86} } May 1989 Volume 81, Number 2 @Article{CoquandGW89, author={Thierry Coquand and Carl Gunter and Glynn Winskel}, title={Domain Theoretic Models of Polymorphism}, pages={123--167}, journal=iandcomp, month=may, year=1989, volume=81, number=2, xxx-references={Gunter87} } @Article{AbrusciM89, author={V. Michele Abrusci and Gianfranco Mascari}, title={A Logic of Recursion}, pages={168--226}, journal=iandcomp, month=may, year=1989, volume=81, number=2, xxx-references={HarelK84, Poigne86} } @Article{Milner89, author={Robin Milner}, title={A Complete Axiomatisation for Observational Congruence of Finite-State Behaviors}, pages={227--247}, journal=iandcomp, month=may, year=1989, volume=81, number=2 } June 1989 Volume 81, Number 3 @Article{StreettE89, author={Robert S. Streett and E. Allen Emerson}, title={An Automata Theoretic Decision Procedure for the Propositional Mu-Calculus}, pages={249--264}, journal=iandcomp, month=jun, year=1989, volume=81, number=3, xxx-references={KfouryP75, McNaughton66, Streett82} } @Article{Senizergues89, author={G. S{\'e}nizergues}, title={Church-{Rosser} Controller Rewriting Systems and Equivalence problems for Deterministic Context-Free Languages}, pages={265--279}, journal=iandcomp, month=jun, year=1989, volume=81, number=3, xxx-references={GinsburgG66b, Valiant74} } @Article{Istrail84, author={Sorin Istrail}, title={An Arithmetical Hierarchy in Propositional Dynamic Logic}, pages={280--289}, journal=iandcomp, month=jun, year=1989, volume=81, number=3 } @Article{Hrbacek89, author={Karel Hrbacek}, title={Convex Powerdomains {II}}, pages={290--317}, journal=iandcomp, month=jun, year=1989, volume=81, number=3, xxx-references={Hrbacek87} } @Article{CoppersmithTR89, author={Don Coppersmith and Prabhakar Raghavan and Martin Tompa}, title={Parallel Graph Algorithms That Are Efficient on Average}, pages={318--333}, Journal=iandcomp, month=jun, year=1989, volume=81, number=3, xxx-references={Cook85} } @Article{ColeV89, author={Richard Cole and Uzi Vishkin}, title={Faster Optimal Parallel Prefix Sums and List Ranking}, pages={334--352}, journal=iandcomp, month=jun, year=1989, volume=81, number=3, xxx-references={ColeV86} } @Article{StossS89, author={H.-J. Stoss and W. Schnitzlein}, title={Linear-Time Simulation of Multihead {Turing} Machines}, pages={353--363}, journal=iandcomp, month=jun, year=1989, volume=81, number=3 } @Article{WillardR89, author={Dan E. Willard and John H. Reif}, title={Parallel Processing Can Be Harmful: The Unusual Behavior of Interpolation Search}, pages={364--379}, journal=iandcomp, month=jun, year=1989, volume=81, number=3 } July 1989 Volume 82, Number 1 @Article{JouannaudK89, author={Jean-Pierre Jouannaud and Emmanuel Kounalis}, title={Automatic Proofs by Induction in Theories without Constructors}, pages={1--33}, journal=iandcomp, month=jul, year=1989, volume=82, number=1, xxx-references={BergstraK84, Dershowitz85} } @Article{CaiH89, author={{Jin-Yi} Cai and Lane A. Hemachandra}, title={Enumerative Counting Is Hard}, pages={34--44}, journal=iandcomp, month=jul, year=1989, volume=82, number=1, xxx-references={AmirG88} } @Article{Willard89, title={Lower Bounds for the Addition-Subtraction Operations in Orthogonal Range Queries and Related Problems}, author={Dan E. Willard}, pages={45--64}, journal=iandcomp, month=jul, year=1989, volume=82, number=1 } @Article{Droste89, author={Manfred Droste}, title={Recursive Domain Equations for Concrete Data Structures}, pages={65--80}, journal=iandcomp, month=jul, year=1989, volume=82, number=1 } @Article{LynchS89, author={Nancy A. Lynch and Eugene W. Stark}, title={A Proof of the {Kahn} Principle for Input/Output Automata}, pages={81--92}, journal=iandcomp, month=jul, year=1989, volume=82, number=1, abstract={We use \emph{input/output automata} to define a simple and general model of networks of concurrently executing, nondeterministic processes that communicate through unidirectional, named \emph{ports}. A notion of the \emph{input/output relation} computed by a process is defined, and \emph{determinate} processes are defined to be processes whose input/output relations are single-valued. We show that determinate processes compute continuous functions, and that networks of determinate processes obey \emph{Kahn's fixed-point principle}. Although these results are already known, our contribution lies in the fact that the input/output automata model yields extremely simple proofs of them (the simplest we have seen), in spite of its generality.}, xxx-references={FPC::BrockA81, THESIS::Cadiou72, ICALP::Faustini82, LICS::GaifmanP87, IP::Kahn74, MICS::Kok87, MIT::LynchT87, ICALP::PanangadenS88, BEATCS::Rabinovich87, POPL::Stark87} } @Article{SinclairJ89, author={Alistair Sinclair and Mark Jerrum}, title={Approximate Counting, Uniform Generation and Rapidly Mixing {Markov} Chains}, pages={93--133}, journal=iandcomp, month=jul, year=1989, volume=82, number=1 } August 1989 Volume 82, Number 2 @Article{BertoniMS89, author={A. Bertoni and G. Mauri and N. Sabadini}, title={Membership Problems for Regular and Context-Free Trace Languages}, pages={135--150}, journal=iandcomp, month=aug, year=1989, volume=82, number=2 } @Article{MontenyohlW89, author={Margaret Montenyohl and Mitchell Wand}, title={Incorporating Static Analysis in a Combinator-Based Compiler}, pages={151--184}, journal=iandcomp, month=aug, year=1989, volume=82, number=2, abstract={We show how restructuring a denotational definition leads to a more efficient compiling algorithm. Three semantics-preserving transformations (static replacement, factoring, and combinator selection) are used to convert a continuation semantics into a formal description of a semantic analyzer and code generator. The compiling algorithm derived below performs type checking before code generation so that type-checking instructions may be omitted from the target code. The optimized code is proved correct with respect to the original definition of the source language. The proof consists of showing that all transformations preserve the semantics of the source language.}, xxx-references={Wand83} } @Article{MoranB89, author={L{\'a}szl{\'o} Babai and Shlomo Moran}, title={Proving Properties of Interactive Proofs by a Generalized Counting Technique}, pages={185--197}, journal=iandcomp, month=aug, year=1989, volume=82, number=2 } @Article{AndreD89, author={Andr{\'e} Arnold and Anne Dicky}, title={An Algebraic Characterization of Transition System Equivalences}, pages={198--229}, journal=iandcomp, month=aug, year=1989, volume=82, number=2 } September 1989 Volume 82, Number 2 @Article{EhrenfeuchtH89, author={Andrzej Ehrenfeucht and David Haussler}, title={Learning Decision Trees from Random Examples}, pages={231--246}, journal=iandcomp, month=sep, year=1989, volume=82, number=3, xxx-references={RivestQ89} } @Article{EhrenfeuchtHKV89, author={Andrzej Ehrenfeucht and David Haussler and Michael Kearns and Leslie Valiant}, title={A General Lower Bound on the Number of Examples Needed for Learning}, pages={247--261}, journal=iandcomp, month=sep, year=1989, volume=82, number=3 } @Article{AndersonMW89, author={Richard J. Anderson and Ernst W. Mayr and Manfred K. Warmuth}, title={Parallel Approximation Algorithms for Bin Packing}, pages={262--277}, journal=iandcomp, month=sep, year=1989, volume=82, number=3, abstract={We study the parallel complexity of polynomial heuristics for the bin packing problem. We show that some well-known (and simple) methods like first-fit-decreasing and best-fit-decreasing are P-complete, and it is hence very unlikely that they can be efficiently parallelized. On the other hand, we exhibit an optimal NC algorithm that achieves the same performance bound as does FFD. Finally, we discuss parallelization of polynomial approximation algorithms for bin packing based on discretization.}, references={ACRPDC::AndersonM1987:17, JALGO::Baker1985:49, TOPLAS::Bar-OnV1985, AFIPS::Batcher1968:307, IPL::DobkinLR1979:96, COMB::VegaL1981:349, STOC::FortuneW1978:114, TCS::GoldschlagerSS1982:105, MISC::HelmboldM1987:39, SICOMP::JohnsonDUGG1974:299, FOCS::KarmarkarK1982:312, STOC::KarpUW1985:22, SIGACT::Ladner1975:583, JACM::LadnerF1980:831, FOCS::Pippenger1979:307, IEEETC::Stone1971:153} } @Article{StompRG89, author={F. A. Stomp and W. P. de Roever and R. T. Gerth}, title={The $\upsilon$ Calculus as an Assertion-Language for Fairness Arguments}, pages={278--322}, journal=iandcomp, month=sep, year=1989, volume=82, number=3 } @Article{FreivaldsSV89, author={R{\=u}si{\c n}{\v s} Freivalds and Carl H. Smith and Mahendran Velauthapillai}, title={Trade-Off among Parameters Effecting Inductive Inference}, pages={323--349}, journal=iandcomp, month=sep, year=1989, volume=82, number=3, abstract={This paper is concerned with the algorithmic learning, by example in the limit, of programs that compute recursive functions. The particular focus is on the relationship of three parameters that effect inferribility: the number of experimental trials, the plurality of approaches to the particular learning problem, and the accuracy of the final result. Each of these parameters has been examined extensively before. However, the precise characterization of the three-way interaction between these parameters is still not known. This paper makes significant progress toward a complete solution.}, xxx-references={BlumB75, DaleyS86, Gold67, PittS88} } @Article{AfratiPP89, title={Corrigendum: The Complexity of Cubical Graphs}, author={Foto Afrati and Christos H. Papadimitriou and George Papageorgiou}, pages={350--353}, journal=iandcomp, month=sep, year=1989, volume=82, number=3, xxx-references={AfratiPP85} } Author Index for Volume 82 -- page 354 October 1989 Volume 83, Number 1 @Article{Turner89, author={Jonathan S. Turner}, title={Approximation Algorithms for the Shortest Common Superstring Problem}, pages={1--20}, journal=iandcomp, month=oct, year=1989, volume=83, number=1 } @Article{ItohT89, title={Structure of Parallel Multipliers for a Class of Fields {$GF(2^m)$}}, author={Toshiya Itoh and Shigeo Tsujii}, pages={21--40}, journal=iandcomp, month=oct, year=1989, volume=83, number=1, xxx-references={ItohT88} } @Article{NivatS89, author={M. Nivat and A. Saoudi}, title={Automata on Infinite Objects and Their Applications to Logic and Programming}, pages={41--64}, journal=iandcomp, month=oct, year=1989, volume=83, number=1, xxx-references={Brainerd68, Kfoury85, McNaughton66} } @Article{VoigtW89, author={Bernd Voigt and Ingo Wegener}, title={Minimal Polynomials for the Conjunction of Functions on Disjoint Variables Can Be Very Simple}, pages={65--79}, journal=iandcomp, month=oct, year=1989, volume=83, number=1 } @Article{AhlswedeZ89, author={R. Ahlswede and Z. Zhang}, title={Coding for Write-Efficient Memory}, pages={80--97}, journal=iandcomp, month=oct, year=1989, volume=83, number=1, xxx-references={RivestS82, WitsenhausenW83a} } @Article{YapABO89, author={Alok Aggarwal and Heather Booth and Joseph O'Rourke and Subhash Suri and Chee K. Yap}, title={Finding Minimal Convex Nested Polygons}, pages={98--110}, journal=iandcomp, month=oct, year=1989, volume=83, number=1, abstract={We consider the problem of finding a polygon nested between two given convex polygons that has a minimal number of vertices. Our main result is an $O(n \log k)$ algorithm for solving the problem, where $n$ is the total number of vertices of the given polygons, and $k$ is the number of vertices of a minimal nested polygon. We also present an $O(n)$ sub-optimal algorithm, and a simple $O(nk)$ optimal algorithm.}, xxx-references={EdelsbrunnerP88} } @Article{Estivill-CastroW89, author={Vladimir Estivill-Castro and Derick Wood}, title={A New Measure of Presortedness}, pages={111--119}, journal=iandcomp, month=oct, year=1989, volume=83, number=1 } November 1989 Volume 83, Number 2 @Article{ImmermanK89, author={Neil Immerman and Dexter Kozen}, title={Definability with Bounded Number of Bound Variables}, pages={121--139}, journal=iandcomp, month=nov, year=1989, volume=83, number=2, abstract={A theory satisfies the $k$-{\em variable property\/} if every first-order formula is equivalent to a formula with at most $k$ bound variables (possibly reused). Gabbay has shown that a model of temporal logic satisfies the $k$-variable property for some $k$ if and only if there exists a finite basis for the temporal connectives over that model. We give a model-theoretic method for establishing the $k$-variable property, involving a restricted Ehrenfeucht-Fraisse game in which each player has only $k$ pebbles. We use the method to unify and simplify results in the literature for linear orders. We also establish new $k$-variable properties for various theories of bounded-degree trees, and in each case obtain tight upper and lower bounds on $k$. This gives the first finite basis theorems for branching-time models of temporal logic.}, references={IC::AmirG1987:66, JSYML::Barwise1977, FUNDI::Ehrenfeucht1961, CRTP::Erimbetov1981, MISC::Fraisse1954, BOOK::FerranteR1979, MISC::Gabbay1981, ICALP::HaferT1987, MISC::Henkin1967, JCSS::Immerman1982, THESIS::Kamp1968, TCS::Kozen1980:221, JCSS::MeyerP1981, JSYML::Poizat1982, BOOK::Rosenstein1982, MISC::Stavi1979, LICS::Thomas1987:245, IC::Tiuryn1984:12} } @Article{ArnoldB89, title={Optimal Word Chains for the {Thue}-{Morse} Word}, author={A. Arnold and S. Brlek}, pages={140--151}, journal=iandcomp, month=nov, year=1989, volume=83, number=2 } @Article{AmericaBKR89, oldkey={RuttenDAK89}, author={Pierre America and Jaco de Bakker and Joost N. Kok and Jan Rutten}, title={Denotational Semantics of a Parallel Object-Oriented Language}, pages={152--205}, journal=iandcomp, month=nov, year=1989, volume=83, number=2, xxx-references={BergstraK84, BakkerZ82} } @Article{SmidOB89, title={Maintaining Multiple Representations of Dynamic Data Structures}, author={Michiel H. M. Smid and Mark H. Overmars and Leen Torenvliet and Peter {van Emde Boas}}, pages={206--233}, journal=iandcomp, month=nov, year=1989, volume=83, number=2 } @Article{YeshaFLR89, title={On the Power of Concurrent-Write {PRAM}s With Read-Only Memory}, author={F. E. Fich and M. Li and P. Ragde and Y. Yesha}, pages={234--244}, journal=iandcomp, month=nov, year=1989, volume=83, number=2 } @Article{ChoG89, author={Yongkyun Cho and Seymour Ginsburg}, title={Decision Problems of Object histories}, pages={245--263}, journal=iandcomp, month=nov, year=1989, volume=83, number=2, xxx-references={GinsburgG87} } December 1989 Volume 83, Number 3 @Article{GermanCH89, author={Steven M. German and Edmund M. Clarke and Joseph Y. Halpern}, title={Reasoning about Procedures as Parameters in the Language {L4}}, pages={265--359}, journal=iandcomp, month=dec, year=1989, volume=83, number=3, abstract={We provide a sound and relatively complete axiom system for partial correctness assertions in an Algol-like language with procedures passed as parameters, but with no global values (known traditionally as L4). The axiom system allows us to reason syntactically about programs and to construct proofs for assertions about complicated programs from proofs of assertions about their components. Such an axiom system has been sought by a number of researchers, but no previously published solution has been entirely satisfactory. Our axiom system extends the natural style of reasoning used in previous Hoare systems to programs with procedures of higher type. The details of the proof that our axiom system is relatively complete in the sense of Cook may be of independent interest, because we introduce results about expressiveness for programs with higher types that are useful beyond the immediate problem of the language L4. We also prove a new incompleteness result that applies to our logic and to similar Hoare logics.}, xxx-references={Grabowski85, Urzyczyn83a} } Author Index for Volume 83 -- pages 360-361 Cumulative Subject Index for Volumes 80-83 -- pages 362-367 January 1990 Volume 84, Number 1 @Article{GeorgakopoulosK90, author={George Georgakopoulos and Dimitris Kavadias}, title={The Banker's Problem with Precedences}, pages={1--12}, journal=iandcomp, month=jan, year=1990, volume=84, number=1 } @Article{Khuller90, author={Samir Khuller}, title={Extending Planar Graph Algorithms to {$K_{3,3}$}-Free Graphs}, pages={13--25}, journal=iandcomp, month=jan, year=1990, volume=84, number=1, xxx-references={Vazirani89} } @Article{Spreen90, author={Dieter Spreen}, title={Computable One-to-One Enumerations of Effective Domains}, pages={26--46}, journal=iandcomp, month=jan, year=1990, volume=84, number=1 } @Article{LazrekLT90, author={Azeddine Lazrek and Pierre Lescanne and Jean-Jacques Thiel}, title={Tools for Proving Inductive Equalities, Relative Completeness, and $\omega$-Completeness}, pages={47--70}, journal=iandcomp, month=jan, year=1990, volume=84, number=1, abstract={Inductive theorems are properties valid in the initial algebra. A now popular tool for proving them in equational theories or abstract data types is based on proof by consistency. This method uses a completion procedure and requires two essential properties of the specification, namely relative completeness and $\omega$-completeness. This paper investigates ways of proving them. For the first one, the complement algorithm is presented. It is based on unification and computation of coverings and complements. For the second one, a technique based on discrimination of pairs of normal forms is explained and illustrated through examples.}, xxx-references={Plaisted85} } @Article{Hagerup90, author={Torben Hagerup}, title={Optimal Parallel Algorithms on Planar Graphs}, pages={71--96}, journal=iandcomp, month=jan, year=1990, volume=84, number=1, abstract={Few existing parallel graph algorithms achieve optimality when applied to very sparse graphs such as planar graphs. We describe optimal PRAM algorithms for the connected components, spanning tree, biconnected components, and strong orientation problems that work on classes of undirected graphs including planar graphs and graphs of bounded genus. The running times achieved for $n$-vertex input graphs are $O(\log n)$ on the CRCW PRAM and $O(\log n\log^* n)$ on the EREW PRAM\@. We also give (non-optimal) randomized EREW PRAM algorithms using $O(\log n)$ time and $n$ processors, and non-uniform deterministic EREW PRAM algorithms using $O(\log n)$ time and $O(n^2)$ processors.}, references={AWC::AndersonM1988, BOOK::Bollobas1978, CACM::ChinLC1982:659, IC::ColeV1986:32, FOCS::ColeV1986:478, SICOMP::ColeV1988, MISC::ColeV1988, IC::ColeV1989:334, SCG::DadounK1987, ARCS::EppsteinG1988, SICOMP::FichRW1988, FOCS::Gazit1986:492, BOOK::GibbonsR1988, SIDMA::GoldbergPS1988, AWC::Hagerup1988, IPL::Hagerup1988, SICOMP::HagerupCD1989, CACM::HirschbergCS1979:461, ICFCT::KoubekK1985, MISC::LeisersonP1987, FOCS::MillerR1985:478, IPL::NathM1982, SPAA::Phillips1989, SICOMP::Reif1984, JALGO::ShiloachV1982:57, SICOMP::TarjanV1985, SICOMP::TsinC1984} } @Article{YungALS90, author={Yehuda Afek and Gad M. Landau and Baruch Schieber and Moti Yung}, title={The Power of Multimedia: Combining Point-to-Point and Multiaccess Networks}, pages={97--118}, journal=iandcomp, month=jan, year=1990, volume=84, number=1, xxx-references={ColeV86} } @Article{Cai90, author={{Jin-yi} Cai}, title={A Note on the Determinant and Permanent Problem}, pages={119--127}, journal=iandcomp, month=jan, year=1990, volume=84, number=1 } February 1990 Volume 84, Number 2 @Article{AmericaB90, author={Pierre America and Frank de Boer}, title={Proving Total Correctness of Recursive Procedures}, pages={129--162}, journal=iandcomp, month=feb, year=1990, volume=84, number=2 } @Article{EngelfrietR90, refkey={C764}, author={Joost Engelfriet and Grzegorz Rozenberg}, title={A Comparison of Boundary Graph Grammars and Context-Free Hypergraph Grammars}, pages={163--206}, journal=iandcomp, month=feb, year=1990, volume=84, number=2, xxx-references={AhoU71, Cook85, EngelfrietL89, RozenbergW86} } @Article{Sakata90, author={Shojiro Sakata}, title={Extension of the {Berlekamp}-{Massey} Algorithm to {$N$} Dimensions}, pages={207--239}, journal=iandcomp, month=feb, year=1990, volume=84, number=2, xxx-references={Imai77} } Author Index for Volume 84 -- page 240 March 1990 Volume 85, Number 1 @Article{Fulk90, author={Mark A. Fulk}, title={Prudence and Other Conditions on Formal Language Learning}, pages={1--11}, journal=iandcomp, month=mar, year=1990, volume=85, number=1, xxx-references={BlumB75, Feldman72, Gold67, OshersonSW82, OshersonW82} } @Article{Courcelle90, author={Bruno Courcelle}, title={The Monadic Second-Order Logic of Graphs. {I}. {Recognizable} Sets of Finite Graphs}, pages={12--75}, journal=iandcomp, month=mar, year=1990, volume=85, number=1, xxx-references={EilenbergW67, MezeiW67} } @Article{BruceMM90, title={The Semantics of Second-Order Lambda Calculus}, author={Kim B. Bruce and Albert R. Meyer and John C. Mitchell}, pages={76--134}, journal=iandcomp, month=mar, year=1990, volume=85, number=1, abstract={In the second-order (polymorphic) typed lambda calculus, lambda abstraction over type variables leads to terms denoting polymorphic functions. Straightforward cardinality considerations show that a naive set-theoretic interpretation of the calculus is impossible. We give two definitions of semantic models for this language and prove them equivalent. Our syntactical ``environmental model'' definition and a more algebraic ``combinatory model'' definition for the polymorphic calculus correspond to analogous model definitions for untyped lambda calculus. Soundness and completeness theorems are proved using the environmental model definition. We verify that some specific interpretations of the calculus proposed in the literature indeed yield models in our sense.}, xxx-references={BarendregtR83, CoquandH88, CoquandGW89, Koymans82, MacQueenPS86, Meyer82, Mitchell88} } April 1990 Volume 85, Number 2 @Article{Tennent90, author={Robert Tennent}, title={Semantical Analysis of Specification Logic}, pages={135--162}, journal=iandcomp, month=apr, year=1990, volume=85, number=2, abstract={The specification logic of J. C. Reynolds is a partial-correctness logic for Algol 60-like languages with procedures. It is interpreted here as an intuitionistic theory, using a form of possible-world semantics first applied to programming-language interpretation by Reynolds and F. J. Oles to give an abstract treatment of stack-oriented storage management. The model provides a satisfactory solution to all previously-known problems with the interpretation of specification logic; however, unexpected new problems have been discovered in doing this work, and these remain unsolved.} } @Article{Meinel90, author={Christoph Meinel}, title={Polynomial Size {$\Omega$}-Branching Programs and Their Computational Power}, pages={163--182}, journal=iandcomp, month=apr, year=1990, volume=85, number=2, xxx-references={Wegener84} } @Article{Conner90, author={Michael Conner}, title={Sequential Machines Realized by Group Representations}, pages={183--201}, journal=iandcomp, month=apr, year=1990, volume=85, number=2, xxx-references={Zeiger67a} } @Article{Walker90, title={Bisimulation and Divergence}, author={D. J. Walker}, pages={202--241}, journal=iandcomp, month=apr, year=1990, volume=85, number=2, xxx-references={Milner89} } Author Index for Volume 85 -- page 242 May 1990 Volume 86, Number 1 @Article{ChangFD90, author={Chien-I Chang and Simon C. Fan and Lee D. Davisson}, title={On Numerical Methods of Calculating the Capacity of Continuous-Input Discrete-Output Memoryless Channels}, pages={1--13}, journal=iandcomp, month=may, year=1990, volume=86, number=1 } @Article{KapurNO90, author={Deepak Kapur and Paliath Narendran and Friedrich Otto}, title={On Ground-Confluence of Term Rewriting Systems}, pages={14--31}, journal=iandcomp, month=may, year=1990, volume=86, number=1, xxx-references={Plaisted85} } @Article{AshHP90, author={C. J. Ash and T. E. Hall and J. E. Pin}, title={On the Varieties of Languages Associated with Some Varieties of Finite Monoids with Commuting Idempotents}, pages={32--42}, journal=iandcomp, month=may, year=1990, volume=86, number=1 } @Article{KanellakisS90, author={Paris C. Kanellakis and Scott A. Smolka}, title={{CCS} Expressions, Finite State Processes, and Three Problems of Equivalence}, pages={43--68}, journal=iandcomp, month=may, year=1990, volume=86, number=1, xxx-references={BensonB88} } @Article{StrothotteS90, author={J{\"o}rg-R{\"u}diger Sack and Thomas Strothotte}, title={A Characterization of Heaps and Its Applications}, pages={69--86}, journal=iandcomp, month=may, year=1990, volume=86, number=1 } @Article{Bodlaender90, author={Hans L. Bodlaender}, title={The Complexity of Finding Uniform Emulations on Paths and Ring Networks}, pages={87--106}, journal=iandcomp, month=may, year=1990, volume=86, number=1, xxx-references={BodlaenderL86} } @Article{Litow90, title={Parallel Complexity of the Regular Code Problem}, author={Bruce E. Litow}, pages={107--114}, journal=iandcomp, month=may, year=1990, volume=86, number=1, xxx-references={Cook85} } June 1990 Volume 86, Number 2 @Article{Asperti90, title={Stability and Computability in Coherent Domains}, author={Andrea Asperti}, pages={115--139}, journal=iandcomp, month=jun, year=1990, volume=86, number=2, xxx-references={GianniniL84} } @Article{Frederickson90, title={A Distributed Shortest Path Algorithm for a Planar Network}, author={Greg N. Frederickson}, pages={140--159}, journal=iandcomp, month=jun, year=1990, volume=86, number=2, abstract={An algorithm is presented for finding a single source shortest path tree in a planar undirected distributed network with nonnegative edge costs. The number of messages used by the algorithm is $O(n^{5/3})$ on an $n$-node network. Distributed algorithms are also presented for finding a breadth-first spanning tree in a general network, for finding a shortest path tree in a general network, for finding a separator of a planar network, and for finding a division of a planar network.} } @Article{AllenderW90, title={Kolmogorov Complexity and Degrees of Tally Sets}, author={Eric Allender and Osamu Watanabe}, pages={160--178}, journal=iandcomp, month=jun, year=1990, volume=86, number=2, abstract={We show that either \[E^p_m({\rm TALLY}) = E^p_{btt}({\rm TALLY})\] or \[E^p_m({\rm TALLY}) \subset E^p_{1-tt}({\rm TALLY}) \subset E^p_{2-tt}({\rm TALLY}) \subset E^p_{3-tt}({\rm TALLY}) \ldots, \] where $E^p_r({\rm TALLY})$ denotes the class of sets which are equivalent to a tally set under $\leq^p_r$ reductions. Furthermore, the question of whether or not $E^p_m({\rm TALLY}) = E^p_{btt}({\rm TALLY})$ is equivalent to the question of whether or not $NE$ predicates can be solved in deterministic exponential time. The proofs use the techniques of generalized Kolmogorov complexity. As corollaries to some of the main results, we obtain new results about the Kolmogorov complexity of sets in $P$.} } @Article{GoldstineKW90, title={On Measuring Nondeterminism in Regular Languages}, author={Jonathan Goldstine and C. M. R. Kintala and Detlef Wotschke}, pages={179--194}, journal=iandcomp, month=jun, year=1990, volume=86, number=2 } @Article{FulopV90, title={A Complete Rewriting System for a Monoid of Tree Transformation Classes}, author={Z. F{\"u}l{\"o}p and S. V{\'a}gv{\"o}lgyi}, pages={195--212}, journal=iandcomp, month=jun, year=1990, volume=86, number=2, xxx-references={Baker79b} } Author Index for Volume 86 -- page 213 July/August 1990 Volume 87, Numbers 1/2 Special Issue: Selections from 1988 IEEE Symposium on Logic in Computer Science @Article{Gurevich90, title={Preface}, author={Yuri Gurevich}, pages={1}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2} } @Article{Winskel90, title={A Compositional Proof System on a Category of Labelled Transition Systems}, author={Glynn Winskel}, pages={2--57}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::Winskel1988:142}, references={IC::Winskel1987:197} } @Article{CleavelandH90, refkey={C1020}, title={Priorities in Process Algebras}, author={Rance Cleaveland and Matthew Hennessy}, pages={58--77}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::CleavelandH1988:193}, abstract={An operational semantics for an algebraic theory of concurrency is developed that incorporates a notion of priority into the definition of the execution of actions. An equivalence based on strong observational equivalence is defined and shown to be a congruence, and a complete axiomatization is given for finite terms. Several examples highlight the novelty and usefulness of our approach.}, xxx-references={CACM::BartlettSW69, TR::BaetenBK85, IC::BergstraK84, IFIP::Brinksma86, TCS::NicolaH84, SCP::Harel87, JACM::HennessyM85, BOOK::Hoare85, BOOK::IMNOS84, TR::KanellakisS83, BOOK::Milner80, JCSS::Milner84, TCS::Milner83, MISC::Pnueli85, BOOK::DOD83} } @Article{FaginHM90, title={A Logic for Reasoning about Probabilities}, author={Ronald Fagin and Joseph Y. Halpern and Nimrod Megiddo}, pages={78--128}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::FaginHM1988:410}, abstract={We consider a language for reasoning about probability which allows us to make statements such as ``the probability of $E_1$ is less than 1/3'' and ``the probability of $E_1$ is at least twice the probability of $E_2$'', where $E_1$ and $E_2$ are arbitrary events. We consider the case where all events are measurable (i.e, represent measurable sets) and the more general case, which is also of interest in practice, where they may not be measurable. The measurable case is essentially a formalization of (the propositional fragment of) Nilsson's probabilistic logic. As we show in a companion paper, the general (nonmeasurable) case corresponds precisely to replacing probability measures by Dempster-Shafer belief functions. In both cases, we provide a complete axiomatization and show that the problem of deciding satisfiability is NP-complete, no worse than that of propositional logic. As a tool for proving our complete axiomatizations, we give a complete axiomatization for reasoning about Boolean combinations of linear inequalities, which is of independent interest. This proof and others make crucial use of results from the theory of linear programming. We then extend the language to allow reasoning about conditional probability, and show that the resulting logic is decidable and completely axiomatizable, by making use of the theory of real closed fields.}, xxx-references={Feldman84, LehmannS82} } @Article{GallierNPS90, title={Rigid {$E$}-Unification: {NP}-Completeness and Applications to Equational Matings}, author={Jean Gallier and Paliath Narendran and David Plaisted and Wayne Snyder}, pages={129--195}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::GallierSNP1988:218} } @Article{BruceL90, title={A Modest Model of Records, Inheritance and Bounded Quantification}, author={Kim B. Bruce and Giuseppe Longo}, pages={196--239}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::BruceL1988:38}, xxx-references={BruceMM90, Mitchell88} } @Article{ComptonL90, title={An Algebra and a Logic for {$NC^1$}}, author={Kevin J. Compton and Claude Laflamme}, pages={240--262}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::ComptonL1988:12}, xxx-references={Cook85, Immerman86} } @Article{Bloom90, title={Can {LCF} be Topped? {Flat} Lattice Models of Typed $\lambda$-Calculus}, author={Bard Bloom}, pages={263--300}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::Bloom1988:282}, xxx-references={Meyer82} } @Article{KolaitisV90, title={0--1 Laws and Decision Problems for Fragments of Second-Order Logic}, author={Phokion Kolaitis and Moshe Vardi}, pages={301--337}, journal=iandcomp, month=jul # "/" # aug, year=1990, volume=87, number={1/2}, preliminary={LICS::KolaitisV1988:2}, references={BlassGK1985:70, Grandjean1983:180, HartmanisIS1985:158, Immerman1986:86} } Author Index for Volume 87 -- page 338 September 1990 Volume 88, Number 1 @Article{KalyanasundaramS90, title={Rounds Versus Time for the Two Person Pebble Game}, author={Bala Kalyanasundaram and Georg Schnitger}, pages={1--17}, journal=iandcomp, month=sep, year=1990, volume=88, number=1 } @Article{PelletierS90, title={Easy Multiplications {II}. Extensions of Rational Semigroups}, author={Maryse Pelletier and Jacques Sakarovitch}, pages={18--59}, journal=iandcomp, month=sep, year=1990, volume=88, number=1, xxx-references={Sakarovitch87} } @Article{ItaiR90, title={Symmetry breaking in distributed networks}, author={Alon Itai and Michael Rodeh}, pages={60--87}, journal=iandcomp, month=sep, year=1990, volume=88, number=1, xxx-references={MansourZ87} } @Article{PaturiSSN90, title={Milking the {Aanderaa} Argument}, author={Ramamohan Paturi and Joel I. Seiferas and Janos Simon and Richard E. Newman-Wolfe}, pages={88--104}, journal=iandcomp, month=sep, year=1990, volume=88, number=1, xxx-references={DurisGPR84, Paul82} } October 1990 Volume 88, Number 2 @Article{MeseguerM90, title={Petri Nets Are Monoids}, author={Jos{\'e} Meseguer and Ugo Montanari}, pages={105--155}, journal=iandcomp, month=oct, year=1990, volume=88, number=2, xxx-references={Benson75, GoltzR83, MainB84, Winskel87} } @Article{DworkM90, title={Knowledge and Common Knowledge in a {Byzantine} Environment: Crash Failures}, author={Cynthia Dwork and Yoram Moses}, pages={156--186}, journal=iandcomp, month=oct, year=1990, volume=88, number=2 } @Article{DauchetHLT90, title={Decidability of the Confluence of Finite Ground Term Rewrite Systems and of Other Related Term Rewrite Systems}, author={Max Dauchet and Thierry Heuillard and Pierre Lescanne and Sophie Tison}, pages={187--201}, journal=iandcomp, month=oct, year=1990, volume=88, number=2, preliminary={LICS::DauchetTHL1987} } Author Index for Volume 88 -- page 202 November 1990 Volume 89, Number 1 @Article{Tofte90, title={Type Inference for Polymorphic References}, author={Mads Tofte}, pages={1--34}, journal=iandcomp, month=nov, year=1990, volume=89, number=1 } @Article{Zaionc90, title={A Characterezation of Lambda Definable Tree Operations}, author={Marek Zaionc}, pages={35--46}, journal=iandcomp, month=nov, year=1990, volume=89, number=1 } @Article{AhlswedeYZ90, title={Creating Order in Sequence Spaces with Simple Machines}, author={Rudolf Ahlswede and Jian-ping Ye and Zhen Zhang}, pages={47--94}, journal=iandcomp, month=nov, year=1990, volume=89, number=1 } December 1990 Volume 89, Number 2 @Article{Leivant90, title={Inductive Definitions Over Finite Structures}, author={Daniel Leivant}, pages={95--108}, journal=iandcomp, month=dec, year=1990, volume=89, number=2, xxx-references={Immerman86} } @Article{BarringtonST90, title={Non-Uniform Automata Over Groups}, author={David A. Mix Barrington and Howard Straubing and Denis Th{\'e}rien}, pages={109--132}, journal=iandcomp, month=dec, year=1990, volume=89, number=2, xxx-references={Cook85, Schutzenberger65a} } @Article{Chlebus90, title={Turing Machines With Access to History}, author={Bogdan S. Chlebus}, pages={133--143}, journal=iandcomp, month=dec, year=1990, volume=89, number=2 } @Article{Finkel90, title={Reduction and covering of infinite reachability trees}, author={Alain Finkel}, pages={144--179}, journal=iandcomp, month=dec, year=1990, volume=89, number=2 } @Article{LiuWZ90, title={Efficient Solution to Some Problems in Free Partially Commutative Monoids}, author={Hai-Ning Liu and C. Wrathall and Kenneth Zeger}, pages={180--198}, journal=iandcomp, month=dec, year=1990, volume=89, number=2 } Author Index for Volume 89 -- page 199 Cumulative Subject Index for Volumes 84--89 -- pages 200--205 January 1991 Volume 90, Number 1 @Article{BohmT91, title={About Systems of Equations, {$X$}-Separability, and Left-Invertibility in the $\lambda$-Calculus}, author={Corrado B{\"o}hm and Enrico Tronci}, pages={1--32}, journal=iandcomp, month=jan, year=1991, volume=90, number=1 } @Article{LinialMR91, title={Results on Learnability and the {Vapnik-Chervonenkis} Dimension}, author={Nathan Linial and Yishay Mansour and Ronald L. Rivest}, pages={33--49}, journal=iandcomp, month=jan, year=1991, volume=90, number=1, xxx-references={EhrenfeuchtHKV89, HausslerKLW91, RivestQ89} } @Article{Kolaitis91, title={The Expressive Power of Stratified Programs}, author={Phokion G. Kolaitis}, pages={50--66}, journal=iandcomp, month=jan, year=1991, volume=90, number=1, xxx-references={Immerman86} } @Article{Huynh91, title={Effective Entropies and Data Compression}, author={Dung T. Huynh}, pages={67--85}, journal=iandcomp, month=jan, year=1991, volume=90, number=1, xxx-references={ChomskyM58, Cook85, Krichevsky87, Kuich70} } @Article{IbarraJCR91, title={Some Classes of Languages in {$\rm NC^1$}}, author={Oscar H. Ibarra and Tao Jiang and Jik H. Chang and Bala Ravikumar}, pages={86--106}, journal=iandcomp, month=jan, year=1991, volume=90, number=1, xxx-references={Cook85, HarrisonI68, RitchieS72} } @Article{Luo91, title={A Higher-Order Calculus and Theory Abstraction}, author={Zhaohui Luo}, pages={107--137}, journal=iandcomp, month=jan, year=1991, volume=90, number=1, xxx-references={CoquandH88, LampsonB88} } February 1991 Volume 90, Number 2 @Article{Bach91, title={Toward A Theory of {Pollard's} Rho Method}, author={Eric Bach}, pages={139--155}, journal=iandcomp, month=feb, year=1991, volume=90, number=2 } @Article{Ko91, title={Separating the Low and High Hierarchies by Oracles}, author={Ker-I Ko}, pages={156--177}, journal=iandcomp, month=feb, year=1991, volume=90, number=2 } @Article{McCollPB91, title={Planar Acyclic Computation}, author={W. F. McColl and M. S. Paterson and B. H. Bowditch}, pages={178--193}, journal=iandcomp, month=feb, year=1991, volume=90, number=2 } @Article{Dybjer91, title={Inverse Image Analysis Generalises Strictness Analysis}, author={Peter Dybjer}, pages={194--216}, journal=iandcomp, month=feb, year=1991, volume=90, number=2 } @Article{CederbaumZ91, title={Towards a Foundation for Semantics in Complete Metric Spaces}, author={Mila E. Majster-Cederbaum and F. Zetzsche}, pages={217--243}, journal=iandcomp, month=feb, year=1991, volume=90, number=2, xxx-references={BakkerZ82, GolsonR83} } Author Index for Volume 90 -- page 244 March 1991 Volume 91, Number 1 @Article{Krause91, title={Lower Bounds for Depth-Restricted Branching Programs}, author={Matthias Krause}, pages={1--14}, journal=iandcomp, month=mar, year=1991, volume=91, number=1 } @Article{BidoitF91, title={General Logical Databases and Programs: Default Logic Semantics and Stratification}, author={Nicole Bidoit and Christine Froidevaux}, pages={15--54}, journal=iandcomp, month=mar, year=1991, volume=91, number=1 } @Article{Amadio91, title={Recursion over Realizability Structures}, author={Roberto M. Amadio}, pages={55--85}, journal=iandcomp, month=mar, year=1991, volume=91, number=1, xxx-references={CoquandGW89, MacQueenPS86, Mitchell88, Moggi88} } @Article{BussH91, title={On Truth-Table Reducibility to {SAT}}, author={Samuel R. Buss and Louise Hay}, pages={86--102}, journal=iandcomp, month=mar, year=1991, volume=91, number=1, xxx-references={LangeJK89} } @Article{PruhsM91, title={The Complexity of Controlled Selection}, author={Kirk Pruhs and Udi Manber}, pages={103--127}, journal=iandcomp, month=mar, year=1991, volume=91, number=1 } @Article{GeigerPP91, title={Axioms and Algorithms for Inferences Involving Probabilistic Independence}, author={Dan Geiger and Azaria Paz and Judea Pearl}, pages={128--141}, journal=iandcomp, month=mar, year=1991, volume=91, number=1 } @Article{GathenS91, title={Boolean Circuits Versus Arithmetic Circuits}, author={Joachim von zur Gathen and Gadiel Seroussi}, pages={142--154}, journal=iandcomp, month=mar, year=1991, volume=91, number=1, xxx-references={BorodinGH82, Cook85} } April 1991 Volume 91, Number 2 @Article{GopalakrishnanRK91, title={Approximate Algorithms for the Knapsack Problem on Parallel Computers}, author={P. S. Gopalakrishnan and I. V. Ramakrishnan and L. N. Kanal}, pages={155--171}, journal=iandcomp, month=apr, year=1991, volume=91, number=2 } @Article{Ronyai91, title={Computing the Order of Centralizers in Linear Groups}, author={Lajos R{\'o}nyai}, pages={172--176}, journal=iandcomp, month=apr, year=1991, volume=91, number=2 } @Article{ChrobakKR91, title={Connectivity vs. Reachability}, author={M. Chrobak and H. Karloff and T. Radzik}, pages={177--188}, journal=iandcomp, month=apr, year=1991, volume=91, number=2 } @Article{Bruijn91, title={Telescopic Mappings in Typed Lambda Calculus}, author={N. G. de Bruijn}, pages={189--204}, journal=iandcomp, month=apr, year=1991, volume=91, number=2, xxx-references={CoquandH88} } @Article{CoanD91, title={Simultaneity Is Harder than Agreement}, author={Brian A. Coan and Cynthia Dwork}, pages={205--231}, journal=iandcomp, month=apr, year=1991, volume=91, number=2, xxx-references={DworkM90} } @Article{LarsenW91, title={Using Information Systems to Solve Recursive Domain Equations}, author={Kim Guldstrand Larsen and Glynn Winskel}, pages={232--258}, journal=iandcomp, month=apr, year=1991, volume=91, number=2 } @Article{Bellantoni91, title={Parallel Random Access Machines with Bounded Memory Wordsize}, author={Stephen J. Bellantoni}, pages={259--273}, journal=iandcomp, month=apr, year=1991, volume=91, number=2 } Author Index for Volume 91 -- page 274 May 1991 Volume 92, Number 1 @Article{ColeV91, title={Approximate Parallel Scheduling. {II}. {Applications} to Logarithmic-Time Optimal Parallel Graph Algorithms}, author={Richard Cole and Uzi Vishkin}, pages={1--47}, journal=iandcomp, month=may, year=1991, volume=92, number=1, xxx-references={ColeV86} } @Article{CardoneC91, title={Type Inference with Recursive Types: Syntax and Semantics}, author={Felice Cardone and Mario Coppo}, pages={48--80}, journal=iandcomp, month=may, year=1991, volume=92, number=1, xxx-references={MacQueenPS86, Mitchell88} } @Article{HornickP91, title={Deterministic {P-RAM} Simulation with Constant Redundancy}, author={Scot W. Hornick and Franco P. Preparata}, pages={81--96}, journal=iandcomp, month=may, year=1991, volume=92, number=1 } @Article{GeskeHS91, title={A Note on Almost-Everywhere-Complex Sets and Separating Deterministic-Time-Complexity Classes}, author={John G. Geske and Dung T. Huynh and Joel I. Seiferas}, pages={97--104}, journal=iandcomp, month=may, year=1991, volume=92, number=1 } @Article{Avron91, title={Simple Consequence Relations}, author={Arnon Avron}, pages={105--140}, journal=iandcomp, month=may, year=1991, volume=92, number=1 } June 1991 Volume 92, Number 2 @Article{CuntoGMP91, title={Fringe Analysis for Extquick: An {\em in Situ\/} Distributive External Sorting Algorithm}, author={Walter Cunto and Gast{\'o}n H. Gonnet and J. Ian Munro and Patricio V. Poblete}, pages={141--160}, journal=iandcomp, month=jun, year=1991, volume=92, number=2 } @Article{Abramsky91, title={A Domain Equation for Bisimulation}, author={Samson Abramsky}, pages={161--218}, journal=iandcomp, month=jun, year=1991, volume=92, number=2, xxx-references={BergstraK84, Hennessy81} } @Article{DuLY91, title={Scheduling Chain-Structured Tasks to Minimize Makespan and Mean Flow Time}, author={Jianzhong Du and Joseph Y-T. Leung and Gilbert H. Young}, pages={219--236}, journal=iandcomp, month=jun, year=1991, volume=92, number=2 } @Article{Venkateswaran91, title={Two Dynamic Programming Algorithms for Which Intepreted Pebbling Helps}, author={H. Venkateswaran}, pages={237--252}, journal=iandcomp, month=jun, year=1991, volume=92, number=2 } @Article{KinberZ91, title={One-Sided Error Probabilistic Inductive Inference and Reliable Frequency Identification}, author={Efim Kinber and Thomas Zeugmann}, pages={253--284}, journal=iandcomp, month=jun, year=1991, volume=92, number=2, abstract={For EX- and BC-type identification, one-sided error probabilistic inference and reliable frequency identification on sets of functions are introduced. In particular, we relate the one to the other and characterize one-sided error probabilistic inference to exactly coincide with reliable frequency identification, on any set $M$. Moreover, we show that reliable EX- and BC-frequency inference forms a new discrete hierarchy having the breakpoints 1, 1/2, 1/3,\dots.}, xxx-references={BlumB75, Chen82} } Author Index for Volume 92 -- page 285 July 1991 Volume 93, Number 1 Special Issue: Selections from 1989 IEEE Symposium on Logic in Computer Science @Article{Parikh91, title={Preface}, author={Rohit Parikh}, pages={iii}, journal=iandcomp, month=jul, year=1991, volume=93, number=1 } @Article{Wand91, title={Type Inference for Record Concatenation and Multiple Inheritance}, author={Mitchell Wand}, pages={1--15}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::Wand1989:92}, abstract={We show that the type inference problem for a lambda calculus with records, including a record concatenation operator, is decidable. We show that this calculus does not have principal types, but does have finite complete sets of types: that is, for any term $M$ in the calculus, there exists an effectively generable finite set of type schemes such that every typing for $M$ is an instance of one the schemes in the set. \par We show how a simple model of object-oriented programming, including hidden instance variables and multiple inheritance, may be coded in this calculus. We conclude that type inference is decidable for object-oriented programs, even with multiple inheritance and classes as first-class values.}, references={MISC::Cardelli1985, IC::Cardelli1988:138, SLFP::ClementDDK1986, ACMCS::CardelliW1985, MISC::Cook1987, TAMS::Hindley1969, CLFP::JategaonkarM1988, POPL::Kamin1988, JCSS::Milner1978, POPL::Mitchell1984, PLDI::OTooleG1989, CLFP::Reddy1988, POPL::Remy1989, POPL::Stansifer1988, POPL::Wand1985, LICS::Wand1987:37, TR::Wand1989} } @Article{MisloveMO91, title={Non-Well-Founded Sets Modeled as Ideal Fixed Points}, author={Michael W. Mislove and Lawrence S. Moss and Frank J. Oles}, pages={16--54}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::MisloveMO1989:263} } @Article{Moggi91, title={Notions of Computation and Monads}, author={Eugenio Moggi}, pages={55--92}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::Moggi1989:14} } @Article{Leivant91, title={Finitely Stratified Polymorphism}, author={Daniel Leivant}, pages={93--113}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::Leivant1989:39} } @Article{Moschovakis91, title={A Model of Concurrency with Fair Merge and Full Recursion}, author={Yiannis N. Moschovakis}, pages={114--171}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::Moschovakis1989:154} } @Article{Breazu-TannenCGS91, title={Inheritance as Implicit Coercion}, author={Val Breazu-Tannen and Thierry Coquand and Carl A. Gunter and Andre Scedrov}, pages={172--221}, journal=iandcomp, month=jul, year=1991, volume=93, number=1, preliminary={LICS::Breazu-TannenCGS1989:112}, xxx-references={Amadio91, Cardelli88, CoquandGW89, CoquandH88, Koymans82, Meyer82} } August 1991 Volume 93, Number 2 @Article{AielloH91, title={Relativized Perfect Zero Knowledge Is Not {BPP}}, author={William Aiello and Johan Hastad}, pages={223--240}, journal=iandcomp, month=aug, year=1991, volume=93, number=2 } @Article{CrescenziP91, title={Completeness in Approximation Classes}, author={Pierluigi Crescenzi and Alessandro Panconesi}, pages={241--262}, journal=iandcomp, month=aug, year=1991, volume=93, number=2 } @Article{PassayT91, title={An Essay in Combinatory Dynamic Logic}, author={Solomon Passay and Tinko Tinchev}, pages={263--332}, journal=iandcomp, month=aug, year=1991, volume=93, number=2, xxx-references={Streett82} } @Article{Hoover91, title={Real Functions, Contraction Mappings and ${P}$-Completeness}, author={H. James Hoover}, pages={333--349}, journal=iandcomp, month=aug, year=1991, volume=93, number=2 } Author Index for Volume 93 -- page 350 September 1991 Volume 94, Number 1 @Article{LarsenS91, title={Bisimulation through Probabilistic Testing}, author={Kim G. Larsen and Arne Skou}, pages={1--28}, journal=iandcomp, month=sep, year=1991, volume=94, number=1 } @Article{BhattDHPRS91, title={Improved Deterministic Parallel Integer Sorting}, author={P. C. P. Bhatt and K. Diks and T. Hagerup and V. C. Prasad and T. Radzik and S. Saxena}, pages={29--47}, journal=iandcomp, month=sep, year=1991, volume=94, number=1, abstract={We consider the problem of deterministic sorting of integers on a parallel RAM (PRAM). The best previous result (Hagerup, 1987, {\sl Inform.\ and Comput.\ }{\bf 75}, pp.\ 39--51) states that $n$ integers of size polynomial in $n$ can be sorted in time $O(\log n)$ on a \textsc{Priority} CRCW PRAM with $O({{n\log\log n}/{\log n}})$ processors. We prove that $n$ integers drawn from a set $\{0,\ldots,m-1\}$ can be sorted on an \textsc{Arbitrary} CRCW PRAM in time $O({{\log n}/{\log\log n}}+\log\log m)$ with a time-processor product of $O(n\log\log m)$. In particular, if $m=n^{(\log n)^{O(1)}}$, the time and number of processors used are $O({{\log n}/{\log\log n}})$ and $O({{n(\log\log n)^2}/{\log n}})$, respectively. This improves the previous result in several respects: The new algorithm is faster, it works on a weaker PRAM model, and it is closer to optimality for input numbers of superpolynomial size. If $\log\log m=O({{\log n}/{\log\log n}})$, the new algorithm is optimally fast, for any polynomial number of processors, and if $\log\log m=(1+\Omega(1))\log\log n$ and $\log\log m=O(\sqrt{\log n})$, it has optimal speedup relative to the fastest known sequential algorithm. The space needed is $O(nm^\epsilon)$, for arbitrary but fixed $\epsilon>0$. \par The sorting algorithm derives its speed from a fast solution to a special list ranking problem of possible independent interest, the \emph{monotonic list ranking problem}. In monotonic list ranking, each list element has an associated key, and the keys are known to increase monotonically along the list. We show that monotonic list ranking problems of size $n$ can be solved optimally in time $O({{\log n}/{\log\log n}})$. \par We also discuss and attempt to solve some of the problems arising in the precise description and implementation of parallel recursive algorithms. As part of this effort, we introduce a new PRAM variant, the \emph{allocated PRAM}.}, references={AWC::AndersonM1988, JACM::BeameH1989:643, MFCS::ChlebusDHR1988, ICFCT::ChlebusDHR1989, IC::ColeV1986:32, FOCS::ColeV1986:478, SICOMP::Cole1988, IC::ColeV1989:334, ARCS::EppsteinG1988, ALGOR::FichRW1988, STOC::FortuneW1978:114, STOC::FredmanW1990:1, FOCS::GrolmuszR1987:89, IC::Hagerup1987:39, ICALP::HagerupN1989, IC::Hagerup1990:71, TCS::KirkpatrickR1984, BOOK::Knuth1973, ICALP::MatiasV1990, TR::MatiasV1990, SICOMP::RajasekaranR1989, SIGACT::Richards1986, CFSTTCS::SaxenaBP1988, IC::Spirakis1988:1} } @Article{Droste91, title={Universal Homogeneous Event Structures and Domains}, author={Manfred Droste}, pages={48--61}, journal=iandcomp, month=sep, year=1991, volume=94, number=1, xxx-references={Droste89, Gunter87, Koymans82} } @Article{Gradel91, title={Simple Sentences That Are Hard to Decide}, author={Erich Gr{\"a}del}, pages={62--82}, journal=iandcomp, month=sep, year=1991, volume=94, number=1 } @Article{LubiwR91, title={A Lower Bound for the Integer Element Distinctiveness Problem}, author={Anna Lubiw and Andr{\'a}s R{\'a}cz}, pages={83--92}, journal=iandcomp, month=sep, year=1991, volume=94, number=1 } @Article{Wanke91, title={Algorithms for Graph Problems on {BNLC} Structured Graphs}, author={Egon Wanke}, pages={93--122}, journal=iandcomp, month=sep, year=1991, volume=94, number=1, abstract={We present algorithms for analyzing single graphs and sets of graphs generated by \emph{boundary node label controlled} (BNLC) graph grammars. This paper extends a unified framework for developing algorithms on hyperedge replacement systems to BNLC graph languages. Graphs in BNLC graph languages do not necessarily have vertex separators of bounded size as graphs in hyperedge replacement systems. We give combinatorial decision and query algorithms on single graphs generated by a deterministic BNLC graph grammar and algorithms for the following question: Does the language of a given BNLC graph grammar contain a graph that fulfills a certain graph property? All algorithms developed in this paper consider the graph grammar as input.}, xxx-references={TCS::Courcelle87, GGACS::Courcelle87, GGACS::EhrigNRR87, WADS::Fernandez-BacaW89, WG::Habel89, GGACS::HabelK87, BEATCS::HabelKV87, BOOK::HopcroftU79, JALGO::Lengauer87, ICALP::LengauerW88, SICOMP::LengauerW88, IC::RozenbergW86, ACTAI::RozenbergW86, DAM::RozenbergW87, TR::Vogler88, FCT::Wanke89} } October 1991 Volume 94, Number 2 @Article{Bakker91, title={Comparative Semantics for Flow of Control in Logic Programming without Logic}, author={J. W. de Bakker}, pages={123--179}, journal=iandcomp, month=oct, year=1991, volume=94, number=2, xxx-references={AmericaBKR89, BakkerZ82} } @Article{TiomkinM91, title={Decidability of Finite Probablistic Propositional Dynamic Logics}, author={M. L. Tiomkin and J. A. Makowsky}, pages={180--203}, journal=iandcomp, month=oct, year=1991, volume=94, number=2, xxx-references={Feldman84} } @Article{Berardi91, title={Retractions on {dI}--domains as a model for {Type:Type}}, author={Stefano Berardi}, pages={204--231}, journal=iandcomp, month=oct, year=1991, volume=94, number=2 } @Article{WaackK91, title={On Oblivious Branching Programs of Linear Length}, author={Stephan Waack and Matthias Krause}, pages={232--249}, journal=iandcomp, month=oct, year=1991, volume=94, number=2, xxx-references={Krause91} } Author Index for Volume 94 -- page 250 November 1991 Volume 95, Number 1 @Article{Bar-NoyDKP91, title={Fault-Tolerant Critical Section Management in Asynchronous Environments}, author={Amotz Bar-Noy and Danny Dolev and Daphne Koller and David Peleg}, pages={1--20}, journal=iandcomp, month=nov, year=1991, volume=95, number=1, abstract={The paper deals with the problem of managing a fault-tolerant critical section in a completely asynchronous distributed network. The existence of a solution to this problem should be contrasted with a basic result of Fischer, Lynch, and Paterson [FLP], proving that in a completely asynchronous network, ``nontrivial agreement" cannot be achieved even when only a single ``benign" processor failure is possible. We present solutions to several versions of the critical section problem in this model. Denote by $t$ the maximum number of possible faulty processors. Processors are allowed to fail while in the critical section, and therefore the critical section must have at least $t+1$ {\sf slots}. In the case where the slots are identical we present two algorithms which require $t+1$ slots. The first is very simple, but requires every correct processor to use the critical section infinitely often. The second solution allows correct processors to quit. In the case of distinct slots we present an algorithm that requires $2t+1$ slots.} } @Article{Engelfriet91, title={Iterated Stack Automata and Complexity Classes}, author={Joost Engelfriet}, pages={21--75}, journal=iandcomp, month=nov, year=1991, volume=95, number=1, xxx-references={Asveld77, DammG86, EngelfrietV87, Greibach70, Greibach78a, ParchmannDS80a, Vogler88} } @Article{ApostolicoC91, title={Optimal Canonization of All Substrings of a String}, author={A. Apostolico and M. Crochemore}, pages={76--95}, journal=iandcomp, month=nov, year=1991, volume=95, number=1 } @Article{BarringtonM91, title={Oracle branching programs and {Logspace} versus {P}}, author={David A. Mix Barrington and Pierre McKenzie}, pages={96--115}, journal=iandcomp, month=nov, year=1991, volume=95, number=1, xxx-references={Cook85} } December 1991 Volume 95, Number 2 @Article{Hromkovic91, title={Nonlinear Lower Bounds on the Number of Processors of Circuits with Sublinear Separators}, author={Juraj Hromkovi{\v{c}}}, pages={117--128}, journal=iandcomp, month=dec, year=1991, volume=95, number=2 } @Article{HausslerKLW91, title={Equivalence of Models for Polynomial Learnability}, author={David Haussler and Michael Kearns and Nick Littlestone and Manfred K. Warmuth}, pages={129--161}, journal=iandcomp, month=dec, year=1991, volume=95, number=2 } @Article{JainS91, title={Learning in the Presence of Partial Explanations}, author={Sanjay Jain and Arun Sharma}, pages={162--191}, journal=iandcomp, month=dec, year=1991, volume=95, number=2, abstract={The effect of a partial explanation as additional information in the learning process is investigated. A scientist performs experiments to gather experimental data about some phenomenon, and then, tries to construct an explanation (or theory) for the phenomenon. A plausible model for the practice of science is an inductive inference machine (scientist) learning a program (explanation) from graph (set of experiments) of a recursive function (phenomenon). It is argued that this model of science is not an adequate one, as scientists, in addition to performing experiments, make use of some approximate partial explanation based on the ``state of the art'' knowledge about that phenomenon. An attempt has been made to model this partial explanation as an additional information in the scientific process. It is shown that inference capability of machines is improved in the presence of such a partial explanation. The quality of this additional information is modeled using certain ``density'' notions. It is shown that additional information about a ``better'' quality partial explanation enhances the inference capability of learning machines as scientists more than a ``not so good'' partial explanation. Similar enhancements to inference of approximations, a more sophisticated model of science, are demonstrated. \par Inadequacies in Gold's paradigm of language learning are investigated. It is argued that Gold's model fails to incorporate certain additional information that children get from their environment. Children are sometimes told about some grammatical rule that enumerates elements of the language. It is argued that these rules are a kind of additional information. They enable children to see in advance elements that are yet to appear in their environment. Also, children are being given some information about what is not in the language. Sometimes, they are rebuked for making incorrect utterances, or are told of a rule that enumerates certain non-elements of the language. An attempt has been made to extend Gold's model to incorporate both the above types of additional information. It is shown that either type of additional information enhances the learning capability of formal language learning devices.}, references={JCSS::Angluin1980, IC::Angluin1980:117, ACMCS::AngluinS1983, MISC::Barzdin1974, HER::BrownB1964, IC::BlumB1975:125, JACM::Blum1967:322, MISC::Case1986, COLT::Case1988, THESIS::Chen1981, COLT::JainSC1989:189, ICALP::CaseL1982, TCS::CaseS1983, BOOK::Dale1976, THESIS::Fulk1985, JCSS::Fulk1990:TA, IC::Fulk1990:1, IC::Gold1967:447, BOOK::HopcroftU1979, TR::JainS1989, CTARAK::JainS1990, ICALP::JainS1990, INFOS::KletteW1980, BOOK::MachteyY1978, IC::OshersonSW1986:69, BOOK::OshersonSW1986, IC::OshersonW1982:123, COGN::OshersonW1982, BOOK::Peirce1958, THESIS::Pitt1984, BOOK::Reilly1970, JSYML::Rogers1958, BOOK::Rogers1967, IC::Royer1986:156, PJMATH::RoseU1963, JACM::Smith1982:1144, MISC::SmithV1986, MFCS::Wiehagen1977, MISC::Wiehagen1978} } @Article{Ponse91, title={Process Expressions and Hoare's Logic: Showing an Irreconcilability of Context-Free Recursion with Scott's Induction Rule}, author={Alban Ponse}, pages={192--217}, journal=iandcomp, month=dec, year=1991, volume=95, number=2, xxx-references={BaetenB88} } @Article{MaheshPS91, title={On Finding the Minimum Bandwidth of Interval Graphs}, author={R. Mahesh and C. Pandu Rangan and Aravind Srinivasan}, pages={218--224}, journal=iandcomp, month=dec, year=1991, volume=95, number=2, xxx-references={Kratsch87} } @Article{Colussi91, title={Correctness and Efficiency of the Pattern Matching Algorithms}, author={Livio Colussi}, pages={225--251}, journal=iandcomp, month=dec, year=1991, volume=95, number=2 } Author Index for Volume 95 -- page 252 Cumulative Subject Index for Volumes 90--95 -- pages 253--259 January 1992 Volume 96, Number 1 @Article{FischerGGL92, title={Optimal Placement of Identical Resources in a Tree}, author={Michael J. Fischer and Nancy D. Griffeth and Leonidas Guibas and Nancy A. Lynch}, pages={1--54}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, abstract={The problem of placing a number $t$ of identical resources at nodes of a tree so as to minimize the total expected cost of servicing a set of $t$ requests arriving randomly at nodes is considered. The cost of servicing a particular set of requests is the total distance in the tree between each request and its assigned resource. Distance is measured by the number of edges along the unique path from the request to the resource. \par Optimal placements can be found in time $O(mt)$, where $m$ is the number of edges in the tree. Allowing resources to be split into fractional-sized pieces which can be placed separately neither reduces the cost of an optimal placement nor provides an obvious way to find optimal placements significantly faster. \par Simple, natural ``fair'' placements are described whose cost differs from optimality by at most the number of edges in the tree. For any fixed tree $T$, the cost of these placements grows as $O(\sqrt{t})$, where the constant implicit in the ``$O$'' notation depends on the size and shape of $T$. In the case of balanced trees with $k$ leaves, that constant is at most $\sqrt{2 k/\pi}$. \par The placement problem becomes somewhat simpler for a complete (rooted) $d$-ary tree with a symmetric probability density function for request arrivals, and in that case slightly stronger results are possible. For example, an optimal placement can be found in time $O(\min\{\ell, \log_d t\} + t)$, where $\ell$ is the height of the tree, and the placement is symmetric and fair.}, xxx-references={BOOK::AhoHU74, BOOK::Feller50, ICDCS::FischerGGL81, FOCS::GuibasRS83, LynchGFG86, ANMS::JogdeoS68, BOOK::PapadimitriouS82, METRIKA::Uhlmann63, METRIKA::Uhlmann66} } @Article{BuchananM92, title={Retrograde Codes and Bounded Synchronization Delay}, author={Hollie L. Buchanan and Michael E. Mays}, pages={55--64}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, xxx-references={GolombG65} } @Article{Dowd92, title={Generic Oracles, Uniform Machines, and Codes}, author={Martin Dowd}, pages={65--76}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, xxx-references={FOCS::BlumI87, JACM::Chaitin69a, JACM::Chaitin75, FOCS::Kannan81b, JACM::Lynch77, FOCS::Mehlhorn73, JACM::PippengerF79} } @Article{BermanS92, title={On the Complexity of Approximating the Independent Set Problem}, author={Piotr Berman and Georg Schnitger}, pages={77--94}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, xxx-references={STOC::Krentel86, FOCS::LeightonR88, JACM::Maier78, STOC::PapadimitriouY88} } @Article{Zeugmann92, title={Highly Parallel Computations Modulo a Number Having Only Small Prime Factors}, author={Thomas Zeugmann}, pages={95--114}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, abstract={Highly parallel algorithms computing the inverse, discrete roots, or a large power modulo a number that has only small prime factors are presented. The elaborated uniform families of Boolean circuits simulataneously achive depth $O(\log n)$ and size $O(n^{O(1)})$ for P-uniformity and depth $O(\log n \log\log n)$ and size $O(n^{O(1)})$ for log-space uniformity.}, xxx-references={FOCS::AdlemanMM77, STOC::AdlemanK88, Cook85, FOCS::Pippenger79b, STOC::ReifT89} } @Article{Ekman92, title={A Note on the Characterization of Weak Bisimulation Congruence in {CCS}}, author={Jan Ekman}, pages={115--118}, journal=iandcomp, month=jan, year=1992, volume=96, number=1 } @Article{Yen92, title={A Unified Approach for Deciding the Existence of Certain {Petri} Net Paths}, author={Hsu-Chun Yen}, pages={119--137}, journal=iandcomp, month=jan, year=1992, volume=96, number=1, xxx-references={STOC::Huynh85, JACM::LandweberR78, LICS::SistlaG87, STOC::Leeuwen74} } February 1992 Volume 96, Number 2 @Article{EmdeS92, title={Aggregating Inductive Expertise on Partial Recursive Functions}, author={Anna-Maria Emde and Britta Schinzel}, pages={139--167}, journal=iandcomp, month=feb, year=1992, volume=96, number=2, xxx-references={JACM::Blum67, BlumB75, STOC::CaseS78, Gold67, OshersonSW86, PittS88, JACM::Smith82} } @Article{HromkovicKMW92, title={Branching Programs Provide Lower Bounds on the Areas of Multilective Deterministic and Nondeterministic {VLSI}-Circuits}, author={Juraj Hromkovi{\v{c}} and Matthias Krause and Christoph Meinel and Stephan Waack}, pages={168--178}, journal=iandcomp, month=feb, year=1992, volume=96, number=2 } @Article{VitterL92, title={Learning in Parallel}, author={Jeffrey Scott Vitter and Jyh-Han Lin}, pages={179--202}, journal=iandcomp, month=feb, year=1992, volume=96, number=2, xxx-references={STOC::AjtaiB84, FOCS::BergerRS89, JACM::BlumerEHW89, Cook85, STOC::KearnsL88, STOC::KearnsLPV87} } @Article{Condon92, title={The Complexity of Stochastic Games}, author={Anne Condon}, pages={203--224}, journal=iandcomp, month=feb, year=1992, volume=96, number=2, xxx-references={JACM::ChandraKS81} } @Article{Stachniak92, title={Resolution Approximation of First-Order Logics}, author={Zbigniew Stachniak}, pages={225--244}, journal=iandcomp, month=feb, year=1992, volume=96, number=2 } @Article{Vovk92, title={Universal Forecasting Algorithms}, author={V. G. Vovk}, pages={245--277}, journal=iandcomp, month=feb, year=1992, volume=96, number=2, xxx-references={JACM::Chaitin75, JACM::GoldreichGM86, FOCS::Hartmanis83, Levin84, STOC::Levin85, FOCS::LittlestoneW89, Martin-Lof66, Solomonoff64a, FOCS::Yao82a} } Author Index for Volume 96 -- page 278 March 1992 Volume 97, Number 1 @Article{ChoH92, title={The Parallel Complexity of Finite-State Automata Problems}, author={Sang Cho and Dung T. Huynh}, pages={1--22}, journal=iandcomp, month=mar, year=1992, volume=97, number=1, xxx-references={Cook85, STOC::KarpUW85, FOCS::MeyerS72, STOC::StockmeyerM73} } @Article{Sakakibara92, title={Efficient Learning of Context-Free Grammars from Positive Structural Examples}, author={Yasubumi Sakakibara}, pages={23--60}, journal=iandcomp, month=mar, year=1992, volume=97, number=1, xxx-references={Angluin80, JACM::Angluin82, Angluin87, FOCS::BermanR87, JACM::Crespi-ReghizziGM78, Gold67, JACM::GrayH72, LevyJ78, JACM::McNaughton67} } @Article{CoanW92, title={Modular Construction of a {Byzantine} Agreement Protocol with Optimal Message Bit Complexity}, author={Brian A. Coan and Jennifer L. Welch}, pages={61--85}, journal=iandcomp, month=mar, year=1992, volume=97, number=1, xxx-references={Bar-NoyDDS92, FOCS::BermanGP89, DolevFFLS82, JACM::DolevR85, JACM::DolevRS90, JACM::PeaseSL80, FOCS::Rabin83} } @Article{Wegener92, title={The Worst Case Complexity of {McDiarmid} and {Reed's} Variant of {BOTTOM-UP HEAPSORT} is less than $n\log n + 1.1n$}, author={Ingo Wegener}, pages={86--96}, journal=iandcomp, month=mar, year=1992, volume=97, number=1, xxx-references={Doberkat84} } @Article{Bartha92, title={An Algebraic Model of Synchronous Systems}, author={Mikl{\'o}s Bartha}, pages={97--131}, journal=iandcomp, month=mar, year=1992, volume=97, number=1, xxx-references={Benson75, FOCS::WrightTWG76} } April 1992 Volume 97, Number 2 @Article{Greenlaw92, title={A Model Classifying Algorithms as Inherently Sequential with Applications to Graph Searching}, author={Raymond Greenlaw}, pages={133--149}, journal=iandcomp, month=apr, year=1992, volume=97, number=2, xxx-references={FOCS::Cole86, STOC::CoppersmithW87} } @Article{Willard92, title={A Density Control Algorithm for Doing Insertions and Deletions in a Sequentially Ordered File in Good Worst-Case Time}, author={Dan E. Willard}, pages={150--204}, journal=iandcomp, month=apr, year=1992, volume=97, number=2, xxx-references={JACM::BakerCW85, STOC::DietzS87, FOCS::Lueker78, JACM::MehlhornT93, JACM::WillardL85, WillardR89, FOCS::YaoY76} } @Article{Bar-NoyDDS92, title={Shifting Gears: Changing Algorithms on the Fly to Expedite {Byzantine} Agreement}, author={Amotz Bar-Noy and Danny Dolev and Cynthia Dwork and H. Raymond Strong}, pages={205--233}, journal=iandcomp, month=apr, year=1992, volume=97, number=2, xxx-references={FOCS::BermanGP89, JACM::DolevRS90, FOCS::MosesW88, JACM::PeaseSL80} } @Article{Jiang92, title={The Synchronization of Nonuniform Networks of Finite Automata}, author={Tao Jiang}, pages={234--261}, journal=iandcomp, month=apr, year=1992, volume=97, number=2, xxx-references={Balzer67, Grasselli75, Kobayashi77, MooreL68, Romani78, Shinahr74, Waksman66} } @Article{Tung92, title={Polynomial Time Algorithms for Sentences over Number Fields}, author={Shih Ping Tung}, pages={262--276}, journal=iandcomp, month=apr, year=1992, volume=97, number=2 } Author Index for Volume 97 -- page 277 May 1992 Volume 98, Number 1 @Article{Regan92, title={Diagonalization, Uniformity, and Fixed-Point Theorems}, author={Kenneth W. Regan}, pages={1--40}, journal=iandcomp, month=may, year=1992, volume=98, number=1, xxx-references={JACM::Blum67, FOCS::BlumI87, JACM::FellowsL88, FOCS::GrollmannS84, JACM::HopcroftU69, STOC::Immerman83, JACM::Ladner75, FOCS::Mehlhorn73, FOCS::MeyerS72, JACM::Rosenberg67} } @Article{Eppstein92, title={Parallel Recognition of Series-Parallel Graphs}, author={David Eppstein}, pages={41--55}, journal=iandcomp, month=may, year=1992, volume=98, number=1, xxx-references={STOC::BerkmanBGSV89, JACM::Brent74, ColeV86, HeY87, JACM::LadnerF80, JACM::TakamizawaNS82, FOCS::TarjanV84, STOC::ValdesTL79} } @Article{Kazakos92, title={Predictive Analog-to-Digital Conversion for Resistance to Data Outliers}, author={P. Papantoni-Kazakos and Dimitri Kazakos}, pages={56--98}, journal=iandcomp, month=may, year=1992, volume=98, number=1, xxx-references={Kazakos87, TsaknakisP88} } @Article{PanangadenS92, title={The Expressive Power of Indeterminate Dataflow Primitives}, author={Prakash Panangaden and Vasant Shanbhogue}, pages={99--131}, journal=iandcomp, month=may, year=1992, volume=98, number=1, xxx-references={JACM::AptP86, LynchS89, FOCS::McAllesterPS88} } @Article{Wiseman92, title={New Binary Codes from a Generalization of {Zinoviev's} Technique}, author={James A. Wiseman}, pages={132--139}, journal=iandcomp, month=may, year=1992, volume=98, number=1 } June 1992 Volume 98, Number 2 Special Issue: Selections from 1990 IEEE Symposium on Logic in Computer Science @Article{Mitchell92, title={Preface}, author={John Mitchell}, pages={141}, journal=iandcomp, month=jun, year=1992, volume=98, number=2 } @Article{BurchCMDH92, title={Symbolic Model Checking: $10^{20}$ States and Beyond}, author={J. R. Burch and E. M. Clarke and K. L. McMillan and D. L. Dill and L. J. Hwang}, pages={142--170}, journal=iandcomp, month=jun, year=1992, volume=98, number=2, preliminary={LICS::BurchCMDH1990:428}, abstract={Many different methods have been devised for automatically verifying finite state systems by examining state-graph models of system behavior. These methods all depend on decision procedures that explicitly represent the state space using a list or a table that grows in proportion to the number of states. We describe a general method that represents the state space \emph{symbolically} instead of explicitly. The generality of our method comes from using a dialect of the Mu-Calculus as the primary specification language. We describe a \emph{model checking} algorithm for Mu-Calculus formulas that uses Bryant's \emph{Binary Decision Diagrams} (Bryant, R. E., 1986, \emph{IEEE Trans.\ Comput.}\ \textbf{C-35}) to represent relations and formulas. We then show how our new Mu-Calculus model checking algorithm can be used to derive efficient decision procedures for CTL model checking, satisfiability of linear-time temporal logic formulas, strong and weak observational equivalence of finite transition systems, and language containment for finite $\omega$-automata. The fixed point computations for each decision procedure are sometimes complex, but can be concisely expressed in the Mu-Calculus. We illustrate the practicality of our approach to symbolic model checking by discussing how it can be used to verify a simple synchronous pipeline circuit.}, references={MISC::BoseF1989, IEEETC::BrowneCDM1986, IEEETC::Bryant1986, IEEETC::Bryant1991, DAC::BurchCL1991, ICVLSI::BurchCL1991, DAC::BurchCMD1990, CTAP::ClarkeDK1990, TOPLAS::ClarkeES1986, TR::Cleaveland1989, AVMFSS::CoudertBM1989, LICS::EmersonL1986, ISCHDLA::FujitaF1989, CAV::Godefroid1990, LICS::GodefroidW1991, ICCD::KimuraC1990, TCS::Kozen1983, LP::MannaW1981, BOOK::Milner1980, TCS::Milner1983, TR::Park1974, CAV::ProbstL1990, TPSD::StirlingW1989, CATPN::Valmari1989, CAV::Valmari1990, ISFTC::YonedaNT1989} } @Article{CroleP92, title={New Foundations for Fixpoint Computations: {FIX}-Hyperdoctrines and the {FIX}-Logic}, author={Roy L. Crole and Andrew M. Pitts}, pages={171--210}, journal=iandcomp, month=jun, year=1992, volume=98, number=2, preliminary={LICS::CroleP1990:489}, xxx-references={CoquandH88, LICS::CroleP90, LICS::Moggi89, Moggi91} } @Article{FreydMRS92, title={Extensional {PER}s}, author={P. Freyd and P. Mulry and G. Rosolini and D. Scott}, pages={211--227}, journal=iandcomp, month=jun, year=1992, volume=98, number=2, preliminary={LICS::FreydMRS1990:346}, xxx-references={LICS::Freyd90} } @Article{KfouryT92, title={Type Reconstruction in Finite Rank Fragments of the Second-Order {$\lambda$}-Calculus}, author={A. J. Kfoury and J. Tiuryn}, pages={228--257}, journal=iandcomp, month=jun, year=1992, volume=98, number=2, preliminary={LICS::KfouryT1990:2}, xxx-references={FOCS::Boehm85, JACM::FortuneLO83, LICS::GianniniR88, KfouryTU93, LICS::KfouryTU89, KfouryTU93, STOC::KfouryTU90, JACM::KfouryTU94, LICS::Leivant89, Mitchell88, LICS::Wand87} } @Article{KolaitisV92, title={Infinitary Logics and 0--1 Laws}, author={Phokion G. Kolaitis and Moshe Y. Vardi}, pages={258--294}, journal=iandcomp, month=jun, year=1992, volume=98, number=2, preliminary={LICS::KolaitisV1990:156}, xxx-references={LICS::AbiteboulV89, STOC::AbiteboulV91, BlassGK85, FOCS::CaiFI89, Compton88, Grandjean83, Immerman86, ImmermanK89, STOC::KolaitisV87, KolaitisV90, FOCS::PacholskiS89, LICS::PacholskiS91, STOC::Vardi82} } Author Index for Volume 98 -- page 295 July 1992 Volume 99, Number 1 @Article{AspertiM92, title={Categorical Models of Polymorphism}, author={Andrea Asperti and Simone Martini}, pages={1--79}, journal=iandcomp, month=jul, year=1992, volume=99, number=1, xxx-references={Amadio91, Berardi91, BruceMM90} } @Article{LarsenM92, title={A Compositional Protocol Verification Using Relativized Bisimulation}, author={Kim G. Larsen and Robin Milner}, pages={80--108}, journal=iandcomp, month=jul, year=1992, volume=99, number=1, xxx-references={STOC::BarringerKP84} } @Article{Robson92, title={Deterministic Simulation of a Single Tape {Turing} Machine by a Random Access Machine in Sub-linear Time}, author={J. M. Robson}, pages={109--121}, journal=iandcomp, month=jul, year=1992, volume=99, number=1, xxx-references={STOC::DymondT83, FOCS::HopcroftPV75, Robson84} } August 1992 Volume 99, Number 2 @Article{FairtloughW92, title={Ordinal Complexity of Recursive Definitions}, author={M. V. H. Fairtlough and S. S. Wainer}, pages={123--153}, journal=iandcomp, month=aug, year=1992, volume=99, number=2 } @Article{Lavalette92, title={Strictness Analysis via Abstract Interpretation for Recursively Defined Types}, author={Gerard R. Renardel de Lavalette}, pages={154--177}, journal=iandcomp, month=aug, year=1992, volume=99, number=2, xxx-references={BarendregtKKS87, Nielson88} } @Article{DarondeauY92, title={Proof Systems for Infinite Behaviours}, author={Philippe Darondeau and Serge Yoccoz}, pages={178--191}, journal=iandcomp, month=aug, year=1992, volume=99, number=2, xxx-references={Hennessy83} } @Article{BenvenisteGSS92, title={A Denotational Theory of Synchronous Reactive Systems}, author={Albert Benveniste and Paul {Le Guernic} and Yves Sorel and Michel Sorine}, pages={192--230}, journal=iandcomp, month=aug, year=1992, volume=99, number=2, xxx-references={McNaughton66, FOCS::Muller63} } @Article{Ore92, title={The Extended Calculus of Constructions {(ECC)} with Inductive Types}, author={Christian-Emil Ore}, pages={231--264}, journal=iandcomp, month=aug, year=1992, volume=99, number=2, xxx-references={LICS::Coquand86, CoquandH88, LICS::Luo89, Luo91, LICS::Mendler87} } Author Index for Volume 99 -- page 265 September 1992 Volume 100, Number 1 @Article{MilnerPW92a, title={A Calculus of Mobile Processes, {I}}, author={Robin Milner and Joachim Parrow and David Walker}, pages={1--40}, journal=iandcomp, month=sep, year=1992, volume=100, number=1, abstract={We present the $\pi$-calculus, a calculus of communicating systems in which one can naturally express processes which have changing structure. Not only may the component agents of a system be arbitrarily linked, but a communication between neighbours may carry information which changes that linkage. The calculus is an extension of the process algebra CCS, following work by Engberg and Nielsen who added mobility to CCS while preserving its algebraic properties. The $\pi$-calculus gains simplicity by removing all distinction between variables and constants; communication links are identified by {\sl names}, and computation is represented purely as the communication of names across links. \par After an illustrated description of how the $\pi$-calculus generalises conventional process algebras in treating mobility, several examples exploiting mobility are given in some detail. The important examples are the encoding into the $\pi$-calculus of higher-order functions (the $\lambda$-calculus and combinatory algebra), the transmission of processes as values, and the representation of data structures as processes. \par The paper continues by presenting the algebraic theory of {\sl strong bisimilarity\/} and {\sl strong equivalence}, including a new notion of equivalence indexed by {\sl distinctions\/}---i.e.\ assumptions of inequality among names. These theories are based upon a semantics in terms of a labelled transition system and a notion of {\sl strong bisimulation}, both of which are expounded in detail in a companion paper. We also report briefly on work-in-progress based upon the corresponding notion of {\sl weak\/} bisimulation, in which internal actions cannot be observed.}, xxx-references={MilnerPW92b, FOCS::Ong88} } @Article{MilnerPW92b, title={A Calculus of Mobile Processes, {II}}, author={Robin Milner and Joachim Parrow and David Walker}, pages={41--77}, journal=iandcomp, month=sep, year=1992, volume=100, number=1, abstract={This is the second of two papers in which we present the $\pi$-calculus, a calculus of mobile processes. We provide a detailed presentation of some of the theory of the calculus developed to date, and in particular we establish most of the results stated in the companion paper.}, xxx-references={MilnerPW92a} } @Article{Haussler92, refkey={C999}, title={Decision Theoretic Generalizations of the {PAC} Model for Neural Net and Other Learning Applications}, author={David Haussler}, pages={78--150}, journal=iandcomp, month=sep, year=1992, volume=100, number=1, abstract={We describe a generalization of the PAC learning model that is based on statistical decision theory. In this model the learner receives randomly drawn examples, each example consisting of an instance $x \in X$ and an outcome $y \in Y$, and tries to find a decision rule $h : X \rightarrow A$, where $h \in {\cal H}$, that specifies the appropriate action $a \in A$ to take for each instance $x$, in order to minimize the expectation of a loss $\ell(y,a)$. Here $X$, $Y$, and $A$ are arbitrary sets, $\ell$ is a real-valued function, and examples are generated according to an arbitrary joint distribution on $X \times Y$. Special cases include the problem of learning a function from $X$ into $Y$, the problem of learning the conditional probability distribution on $Y$ given $X$ (regression), and the problem of learning a distribution on $X$ (density estimation). \par We give theorems on the uniform convergence of empirical loss estimates to true expected loss rates for certain decision rule spaces $\cal H$, and show how this implies learnability with bounded sample size, disregarding computational complexity. As an application, we give distribution-independent upper bounds on the sample size needed for learning with feedforward neural networks. Our theorems use a generalized notion of VC dimension that applies to classes of real-valued functions, adapted from Vapnik and Pollard's work, and a notion of {\em capacity\/} and {\em metric dimension\/} for classes of functions that map into a bounded metric space.}, references={COLT::AbeW1990, MISC::Alexander1985, PTRF::Alexander1987, ML::Angluin1988, ML::AngluinL1988, JCSS::AngluinV1979, TR::AnthonyS1990, CDC::Barron1989, IEEETIT::BarronC1990, IEEETSMC::BartoA1985, NC::BaumH1988, COLT::BenedekI1988, BOOK::Berger1985, BOOK::Billingsley1986, JACM::BlumerEHW1989:929, BOOK::BreimanOS1984, THESIS::Buntine1990, COMPS::BuntineW1991, IEEETIT::ClarkeB1990, COMPS::Hopfield1987, IEEETPAMI::Devroye1988, BOOK::DudaH1973, ANNPR::Dudley1978, LNM::Dudley1984, ANNPR::Dudley1987, NC::DurbinR1989, BOOK::Edelsbrunner1987, IC::EhrenfeuchtHKV1989:247, ZNATA::Farmer1982, PHYSD::FarmerOY1983, BOOK::Ferguson1967, NN::Gullapalli1990, MISC::GyorgyiT1990, ARTII::Haussler1988, ML::Haussler1989, WALT::Haussler1990, IC::Haussler1992:78, IC::HausslerKLW1991:129, COLT::HausslerKS1991, IC::HausslerLW1994:248, DISCG::HausslerW1987, STOC::KearnsLPV1987, FOCS::KearnsS1990, BOOK::Kiefer1987, AMST::KolmogorovT1959, TR::Kulkarni1990, BOOK::Kullback1959, MISC::LeCunDS1990, STATSCI::Lindley1990, COLT::LinialMR1988:56, ML::Littlestone1988, THESIS::MacKay1992, BOOK::Mandelbrot1982, BOOK::McCullaghN1989, NC::MoodyD1989, BOOK::NarendraT1989, COLT::Natarajan1988, TR::Natarajan1989:89-29, TR::Natarajan1989:89-6, ICML::NatarajanT1988, TR::NobelD1990, ANNST::NolanP1987, MISC::Nowlan1990, TR::NowlanH1991, COLT::OpperH1991, PRL::OpperH1991, TR::PoggioG1989, BOOK::Pollard1984, MISC::Pollard1986, MISC::Pollard1990, MISC::Quiroz1989, BOOK::Renyi1970, ANNST::Rissanen1986, BOOK::RumelhartM1986, COLT::ShackelfordV1988, COLT::Sloan1988, PRL::SompolinskyTS1990, ANNPR::Talagrand1994, IJCNN::TishbyLS1989, BOOK::Touretsky1989, BOOK::Touretsky1990, CACM::Valiant1984:1134, BOOK::Vapnik1982, COLT::Vapnik1989, TPA::VapnikC1971, IJNS::WeigendHR1990, BOOK::WeissK1991, SCG::Welzl1988, DISCM::WenocurD1981, NN::White1990, NC::White1990, COLT::Yamanishi1990} } October 1992 Volume 100, Number 2 @Article{Zhang92, title={{dI}-Domains as Prime Information Systems}, author={Guo-Qiang Zhang}, pages={151--177}, journal=iandcomp, month=oct, year=1992, volume=100, number=2 } @Article{Board92, title={The Online Graph Bandwidth Problem}, author={Raymond A. Board}, pages={178--201}, journal=iandcomp, month=oct, year=1992, volume=100, number=2, xxx-references={STOC::BorodinLS87, JACM::Yao80} } @Article{GrooteV92, title={Structured Operational Semantics and Bisimulation as a Congruence}, author={Jan Friso Groote and Frits Vaandrager}, pages={202--260}, journal=iandcomp, month=oct, year=1992, volume=100, number=2, xxx-references={BaetenB88, LICS::CleavelandH88, JACM::HennessyM85} } @Article{GoldstineLW92, title={On the Relation between Ambiguity and Nondeterminism in Finite Automata}, author={Jonathan Goldstine and Hing Leung and Detlef Wotschke}, pages={261--270}, journal=iandcomp, month=oct, year=1992, volume=100, number=2, xxx-references={GoldstineKW90} } Author Index for Volume 100 -- page 271 November 1992 Volume 101, Number 1 @Article{DahlhausM92, title={Query Languages for Hierarchic Databases}, author={E. Dahlhaus and J. A. Makowsky}, pages={1--32}, journal=iandcomp, month=nov, year=1992, volume=101, number=1, xxx-references={Cook85, HarelP84, STOC::Immerman82, STOC::Immerman83} } @Article{VermaR92, title={Tight Complexity Bounds for Term Matching Problems}, author={Rakesh M. Verma and I. V. Ramakrishnan}, pages={33--69}, journal=iandcomp, month=nov, year=1992, volume=101, number=1, xxx-references={FOCS::ColeV86, STOC::CookD82, Cook85, STOC::FortuneW78, STOC::MulmuleyVV87} } @Article{Stransky92, title={A Lattice for Abstract Interpretation of Dynamic ({LISP}-Like) Structures}, author={Jan Stransky}, pages={70--102}, journal=iandcomp, month=nov, year=1992, volume=101, number=1 } @Article{Vakarelov92, title={A Modal Logic for Cyclic Repeating}, author={Dimiter Vakarelov}, pages={103--122}, journal=iandcomp, month=nov, year=1992, volume=101, number=1, xxx-references={Streett82} } @Article{MehlhornPU92, refkey={C928}, title={{$k$} versus {$k+1$} Index Registers and Modifiable versus Non-modifiable Programs}, author={K. Mehlhorn and W. J. Paul and C. Uhrig}, pages={123--129}, journal=iandcomp, month=nov, year=1992, volume=101, number=1, xxx-references={LiV88, STOC::MaassSS87, Paul82} } December 1992 Volume 101, Number 2 @Article{HashiguchiY92, title={String Matching Problems over Free Partially Commutative Monoids}, author={Kosaburo Hashiguchi and Kazuya Yamada}, pages={131--149}, journal=iandcomp, month=dec, year=1992, volume=101, number=2, xxx-references={FOCS::Weiner73} } @Article{NgS92, title={Probabilistic Logic Programming}, author={Raymond Ng and V. S. Subrahmanian}, pages={150--201}, journal=iandcomp, month=dec, year=1992, volume=101, number=2, xxx-references={LICS::KiferL89, Zadeh65, Zadeh68} } @Article{Goerdt92, title={Characterizing Complexity Classes by General Recursive Definitions in Higher Types}, author={Andreas Goerdt}, pages={202--218}, journal=iandcomp, month=dec, year=1992, volume=101, number=2, xxx-references={LICS::Goerdt89, FOCS::Gurevich83, LICS::KfouryTU87} } @Article{PinST92, title={Some Results on the Generalized Star-Height Problem}, author={J. E. Pin and H. Straubing and D. Th{\'e}rien}, pages={219--250}, journal=iandcomp, month=dec, year=1992, volume=101, number=2, xxx-references={Schutzenberger65a, Stern85} } @Article{Dougherty92, title={Adding Algebraic Rewriting to the Untyped Lambda Calculus}, author={Daniel J. Dougherty}, pages={251--267}, journal=iandcomp, month=dec, year=1992, volume=101, number=2, xxx-references={LICS::Breazu-Tannen88a, CoquandH88, JACM::Huet80, JACM::Toyama87} } Author Index for Volume 101 -- page 268 Cumulative Subject Index, Volume 96-101 -- pages 269-275 January 1993 Volume 102, Number 1 @Article{BloomET93, refkey={C1061}, title={Iteration Theories of Synchronization Trees}, author={Stephen L. Bloom and Zolt{\'a}n {\'E}sik and Dirk Taubner}, pages={1--55}, journal=iandcomp, month=jan, year=1993, volume=102, number=1, xxx-references={BakkerZ82, JACM::Salomaa66, FOCS::WrightTWG76} } @Article{ShadeN93, title={Real-Time Semantics for Shared-Variable Concurrency}, author={Eric Shade and K. T. Narayana}, pages={56--82}, journal=iandcomp, month=jan, year=1993, volume=102, number=1, xxx-references={KoymansSRGA88} } @Article{KfouryTU93, title={The Undecidability of the Semi-unification Problem}, author={A. J. Kfoury and J. Tiuryn and P. Urzyczyn}, pages={83--101}, journal=iandcomp, month=jan, year=1993, volume=102, number=1, abstract={The Semi-Unification Problem (SUP) is a natural generalization of both first-order unification and matching. The problem arises in various branches of computer science and logic. Although several special cases of SUP are known to be decidable, the problem in general has been open for several years. We show that SUP in general is undecidable, by reducing what we call the ``boundedness problem'' of Turing machines to SUP. The undecidability of this boundedness problem is established by a technique developed in the mid-1960's to prove related results about Turing machines.}, xxx-references={SICOMP::ChandraV85, LICS::DorreR90, LFP::Henglein88, ICCI::Henglein90, JSYML::Hooper66, POPL::KanellakisM89, FSTTCS::KapurMNS88, POPL::KfouryTU88, MISC::KfouryTU89, LICS::KfouryTU89, CAAP::KfouryTU90, LICS::KfouryT90, WCSL::Leiss87, SIEMENS::Leiss89, POPL::Mairson90, Mitchell83, ISP::Mycroft84, CMUC:: Pudlak88, RTA::Purdom87} } @Article{BuntrockHS93, refkey={C1081}, title={Using Inductive Counting to Simulate Nondeterministic Computation}, author={Gerhard Buntrock and Lane A. Hemachandra and Dirk Siefkes}, pages={102--117}, journal=iandcomp, month=jan, year=1993, volume=102, number=1, abstract={Immerman and Szelepcs\'enyi's inductive counting technique demonstrated that, for space classes, the nondeterministic acceptance mechanism can simulate with no space penalty any reasonable acceptance mechanism based on censuses of configurations. However, the efficiency with which other acceptance mechanisms can simulate nondeterminism remains an open question. This paper uses inductive counting to study the cost of simulating nondeterminism with Valiant's paradigm of unique computation---nondeterministic computation in which each input generates at most one accepting computation. We show that unique computation can simulate nondeterministic computation with a space penalty logarithmic in the ambiguity of the nondeterministic computation tree. Relatedly, we show that unique AuxPDAs and restricted SAC$^1$ circuits can efficiently simulate ambiguity-bounded nondeterministic computation. In particular, all nondeterministic logspace languages of polynomial ambiguity are in $\mathrm{WeakUnambRAC}^1$, and thus are accepted by uniform, weak, unambiguous, shallow circuits.}, remarks={The authors would like to draw attention to the following paper, which is a nice continuation of their work: Rolf Niedermeier and Peter Rossmanith. Unambiguous auxiliary pushdown automata and semi-unbounded fan-in circuits. \emph{Information and Computation}, 118(2):227-245, 1 May 1995.}, references={SICOMP::BorodinCDRT1989:559, BOOK::BalcazarDG1988, BOOK::BalcazarDG1990, BlassG1982:80, ICFCT::BuntrockJLR1991:168, MST::BuhrmanHT1991:179, MST::CaiH1990:95, JACM::Cook1971:4, STOC::Cook1979:338, Cook1985:2, ICCI::Geske1990:112, TCS::GoldschlagerP1986:43, SICOMP::GrollmannS1988:309, MFCS::Hemachandra1988:59, JCSS::HemachandraH1993:363, BOOK::HopcroftU1979, SICOMP::Immerman1988:935, SCTC::Lange1990:130, MFCS::LangeR1990:399, LATIN::NiedermeierR1992:387, GICTCS::PapadimitriouZ1983:269, JCSS::Ruzzo1981:365, JCSS::Savitch1970:177, ACTAI::Szelepcsenyi1988:279, IPL::Szepietowski1989:109, THESIS::Toran1988, IPL::Valiant1976:20, JCSS::Venkateswaran1991:380} } @Article{JainS93, title={Learning with the Knowledge of an Upper Bound on Program Size}, author={Sanjay Jain and Arun Sharma}, pages={118--166}, journal=iandcomp, month=jan, year=1993, volume=102, number=1, abstract={Two learning situations are considered: machine identification of programs from graphs of recursive functions (modeling inductive hypothesis formation) and machine identification of grammars from texts of recursively enumerable languages (modeling first language acquisition). Both these learning models are extended to account for situations in which a learning machine is provided additional information in the form of knowledge about an upper-bound on the minimal size program (grammar) for the function (language) being identified. For a number of such extensions, it is shown that larger classes of functions (languages) can be algorithmically identified in the presence of upper-bound information. \par Numerous interesting relationships are shown between different models of learning, number of anomalies allowed in the inferred program (grammar), and number of anomalies allowed in the upper-bound information.}, references={MISC::Barzdin1974, IC::BlumB1975, JACM::Blum1967, MST::Case1974, CLT::Case1988, CLT::CaseJS1989, MISC::CaseL1982, TCS::CaseS1983, THESIS::Fulk1985, JCSS::Fulk1990:TA, IC::Fulk1990, EIK::FreivaldsW1979, IC::Gold1967, BOOK::HopcroftU1979, ICALP::JainS1990, IC::JainS1991:162, BOOK::LangendoenP1984, BOOK::MachteyY1978, COGNS::StobOW1982, COGN::StobOW1984, IC::OshersonSW1986:69, BOOK::StobOW1986, IC::OshersonW1982, COGN::OshersonW1982, THESIS::Pitt1984, JSYML::Rogers1958, BOOK::Rogers1967, IC::Royer1986, JACM::Smith1982, AMS::Smullyan1961, MISC::SmithV1986, BOOK::WexlerC1980, COGN::Wexler1982} } February 1993 Volume 102, Number 2 @Article{SistlaZ93, title={Reasoning in a Restricted Temporal Logic}, author={A. Prasad Sistla and Lenore D. Zuck}, pages={167--195}, journal=iandcomp, month=feb, year=1993, volume=102, number=2, xxx-references={STOC::HartS84, LICS::HalpernS86, McNaughton66, FOCS::Pnueli77, JACM::SistlaC85, SistlaCFNM84, Thomas81, LICS::VardiW86, FOCS::Wolper81} } @Article{DietzfelbingerH93, oldkey={DietzfelbingerM93}, title={An Optimal Parallel Dictionary}, author={Martin Dietzfelbinger and Friedhelm {Meyer auf der Heide}}, pages={196--217}, journal=iandcomp, month=feb, year=1993, volume=102, number=2, xxx-references={FOCS::DietzfelbingerKMHRT88, STOC::DietzfelbingerH90, JACM::FredmanKS84, STOC::KarlinU86, JACM::Upfal84} } @Article{KaufmannK93, title={Routing in Polygons without Rectilinear Visible Corners}, author={Michael Kaufmann and Gerhard Kl{\"a}r}, pages={218--262}, journal=iandcomp, month=feb, year=1993, volume=102, number=2, xxx-references={FOCS::LaPaugh80, JACM::MehlhornP86} } @Article{FleischerSU93, title={A Lower Bound for the Worst Case of {Bottom-Up-Heapsort}}, author={R. Fleischer and B. P. Sinha and C. Uhrig}, pages={263--279}, journal=iandcomp, month=feb, year=1993, volume=102, number=2 } @Article{GrahamHLS93, title={Subcube Fault-Tolerance in Hypercubes}, author={Niall Graham and Frank Harary and Marilynn Livingston and Quentin F. Stout}, pages={280--314}, journal=iandcomp, month=feb, year=1993, volume=102, number=2, xxx-references={BeckerS88, FOCS::Friedman84, STOC::HastadLN87} } Author Index for Volume 102 -- page 315 March 1993 Volume 103, Number 1 @Article{PnueliZ93, title={Probabilistic Verification}, author={Amir Pnueli and Lenore D. Zuck}, pages={1--29}, journal=iandcomp, month=mar, year=1993, volume=103, number=1, xxx-references={FOCS::CourcoubetisY88, Feldman84, LehmannS82, FOCS::Pnueli77, JACM::SistlaC85, FOCS::Vardi85, LICS::VardiW86, FOCS::Wolper81} } @Article{GinsburgSW93, title={Content-Related Interval Queries on Object Histories}, author={Seymour Ginsburg and Dan Simovici and Xiaoyang Wang}, pages={30--67}, journal=iandcomp, month=mar, year=1993, volume=103, number=1, abstract={This paper initiates the investigation of ``content-related'' interval queries on object histories described by computation-tuple sequence schemes (CSS). Four primitive content-related interval queries, two variations for each of them, and two auxiliary interval queries are defined. The following problems are studied: (1)~whether a query preserves CSS-describable sets, (2)~whether a query preserves local-CSS describable sets, and (3)~given a local-CSS describable set, whether a query returns a CSS-describable set.}, references={TCS::DongG1991, IC::GinsburgG1987, ACMTDS::GinsburgT1986, TR::GinsburgT1986, TCS::GinsburgT1986, TCS::GinsburgT1989} } @Article{BeigelGGO93, title={Terse, Superterse, and Verbose Sets}, author={Richard Beigel and William I. Gasarch and John Gill and James C. Owings}, pages={68--85}, journal=iandcomp, month=mar, year=1993, volume=103, number=1, abstract={If $f$ is a function and $A$ is a set then $f\le_T B$ means that $f$ could be computed with an oracle to $B$. This paper launches an investigation of \emph{how many} queries to $B$ are required. Let $F_n^A(x_1,\ldots,x_n)=A(x_1)\cdots A(x_n)$. An oracle Turing machine with oracle $A$ could certainly compute $F_n^A$ with $n$ queries to $A$. There are some sets $A$ (e.g., the halting set) for which $F_n^A$ can be computed with substantially fewer than $n$ queries. One key reason for this is that the questions asked to the oracle can depend on previous answers, i.e., the questions are \emph{adaptive}. We examine when it is possible to save queries. We show that the range of possible query savings is limited by the following theorem: $F_n^A$ cannot be computed with only $\lfloor \log{n} \rfloor$ queries to a set $X$ unless $A$ is recursive. A set $A$ is \emph{terse} if the computation of $F_n^A$ from $A$ \emph{requires} $n$ queries. A set $A$ is \emph{superterse} if the computation of $F_n^A$ from \emph{any} set requires $n$ queries. A set $A$ is \emph{verbose} if $F_{2^n-1}^A$ can be computed with $n$ queries to $A$. We show the following exist: (1) a verbose set in each truth-table degree and a superterse set in each nonzero truth-table degree; and (2) an r.e.\ verbose set in each r.e.\ truth-table degree and an r.e.\ terse set in each nonzero r.e.\ Turing degree.} } @Article{FalaschiLMP93, refkey={C1004}, title={A Model-Theoretic Reconstruction of the Operational Semantics of Logic Programs}, author={Moreno Falaschi and Giorgio Levi and Maurizio Martelli and Catuscia Palamidessi}, pages={86--113}, journal=iandcomp, month=mar, year=1993, volume=103, number=1, abstract={In this paper we define a new notion of truth on Herbrand interpretations extended with variables which allows us to capture, by means of suitable models, various observable proerties, such as the ground success set, the set of atomic consequences, and the computed answer substitutions. The notion of truth extends the classical one to account for non-ground formulas in the interpretations. The various operational semantics are all models. An ordering on interpretations is defined to overcome the problem that the intersection of a set of models is not necessarily a model. The set of interpretations with this partial order is shown to be a complete lattice, and the greatest lower bound of any set of models is shown to be a model. Thus there exists a least model, which is the least herbrand model and therefore the ground success set semantics. Richer operational semantics are non-least models, which can, however, be effectively defined by fixpoint constructions. The model corresponding to the computed answer substitutions operational semantics is the most primitive one (the other can be easily obtained from it).}, xxx-references={TR::Apt87, TR::BarbutiGL89, ICLP::BoerKPR89, MFCS::BoerKPR89, TR::Clark79, JACM::EmdenK76, FGCS::FalaschiL88, ICLP::FalaschiLMP88, TCS::FalaschiLMP89, LICS::GaifmanS89, POPL::GaifmanS89, FLFP::LassezMM87, ICLP::LeviP87, ICLP::Levi88, TR::LeviM88, BOOK::Lloyd84, MISC::Maher87, FGCS::Murakami88, JCSS::Smuth78} } @Article{MeseguerG93, refkey={C699}, title={Order-Sorted Algebra Solves the Constructor-Selector, Multiple Representation, and Coercion Problems}, author={Jos{\'e} Meseguer and Joseph A. Goguen}, pages={114--158}, journal=iandcomp, month=mar, year=1993, volume=103, number=1, abstract={Structured data are generally composed from constituent parts by constructors and decomposed by selectors. We prove that the usual many-sorted algebra approach to abstract data types \emph{cannot} capture this simple intuition in a satisfactory way. We also show that order-sorted algebra \emph{does} solve this problem, and many others concerning ill-defined and erroneous expressions, in a simple and natural way. In particular, we show how order-sorted algebra supports an elegant solution to the problems of multiple representations and coercions. The essence of order-sorted algebra is that sorts have \emph{subsorts}, whose semantic interpretation is the subset relation on the carriers of algebras.}, xxx-references={JACM::Huet80} } April 1993 Volume 103, Number 2 @Article{Staiger93, title={Kolgomorov Complexity and {Hausdorff} Dimension}, author={Ludwig Staiger}, pages={159--194}, journal=iandcomp, month=apr, year=1993, volume=103, number=2, xxx-references={JACM::Chaitin66, JACM::Chaitin69a, ChomskyM58, Gacs86, FOCS::KorenjakH66, Kuich70, Martin-Lof66, Solomonoff64a, Solomonoff64b, Staiger83, Wagner79} } @Article{MusikaevT93, title={Limitations of the Program Memory and the Expressive Power of Dynamic Logics}, author={I. Kh. Musikaev and M. A. Taitslin}, pages={195--203}, journal=iandcomp, month=apr, year=1993, volume=103, number=2, xxx-references={Tiuryn84} } @Article{AcetoH93, title={Towards Action-Refinement in Process Algebras}, author={L. Aceto and M. Hennessy}, pages={204--269}, journal=iandcomp, month=apr, year=1993, volume=103, number=2, xxx-references={AcetoH94, JACM::BrookesHR84, BergstraK84, JACM::CastellaniH89, JACM::HennessyM85} } @Article{Peleg93, refkey={C935}, title={Distance-Dependent Distributed Directories}, author={David Peleg}, pages={270--298}, journal=iandcomp, month=apr, year=1993, volume=103, number=2, abstract={Distributed systems often make use of {\em directory servers\/} enabling the storage and retrieval of global information in the network. In many practical situations, the data is directly related to particular sites of the network, and therefore the desired retrieval characteristics are dependent on the network topology; for example, priority is given to having high accessibility to data generated in nearby locations. This paper defines the concept of distance-dependent directories, and then proposes appropriate accessibility measures and presents strategies for constructing such directories. The construction methods are based on efficient solutions to a new type of graph-covering problem. As an application, it is shown how to use a distance-dependent directory for implementing a name-server component for a routing scheme.}, xxx-references={STOC::AwerbuchBLP89, FOCS::AwerbuchP90a, FOCS::AwerbuchP90b, JACM::PelegU89} } @Article{RivestS93, title={Inference of Finite Automata Using Homing Sequences}, author={Ronald L. Rivest and Robert E. Schapire}, pages={299--347}, journal=iandcomp, month=apr, year=1993, volume=103, number=2, abstract={We present new algorithms for inferring an unknown finite-state automaton from its input/output behavior, even in the absence of a means of resetting the machine to a start state. A key technique used is inference of a {\em homing sequence\/} for the unknown automaton. \par Our inference procedures experiment with the unknown machine, and from time to time require a teacher to supply counterexamples to incorrect conjectures about the structure of the unknown automaton. In this setting, we describe a learning algorithm that, with probability $1 - \delta$, outputs a correct description of the unknown machine in time polynomial in the automaton's size, the length of the longest counterexample, and $\log(1/\delta)$. We present an analogous algorithm that makes use of a diversity-based representation of the finite-state system. Our algorithms are the first which are provably effective for these problems, in the absence of a ``reset.'' \par We also present probabilistic algorithms for permutation automata which do not require a teacher to supply counterexamples. For inferring a permutation automaton of diversity $D$, we improve the best previous time bound by roughly a factor of $D^3/\log D$.}, xxx-references={Angluin78, Angluin81, Angluin87, Gold78, STOC::KearnsV89, JACM::PittW93, FOCS::RivestS87, JACM::RivestS94, JACM::Tarjan75} } Author Index for Volume 103 -- page 348 May 1993 Volume 104, Number 1 Special Issue: Selections from 1990 IEEE Symposium on Logic in Computer Science @Article{Mitchell93, title={Preface}, author={John Mitchell}, pages={1}, journal=iandcomp, month=may, year=1993, volume=104, number=1 } @Article{AlurCD93, title={Model-Checking in Dense Real-time}, author={Rajeev Alur and Costas Courcoubetis and David Dill}, pages={2--34}, journal=iandcomp, month=may, year=1993, volume=104, number=1, preliminary={LICS::AlurCD1990:414}, xxx-references={FOCS::AlurH89, LICS::BurchCMDH90, LICS::HarelLP90, LICS::HenzingerNSY92, LICS::Lewis90, FOCS::Pnueli77} } @Article{AlurH93, title={Real-Time Logics: Complexity and Expressiveness}, author={Rajeev Alur and Thomas Henzinger}, pages={35--77}, journal=iandcomp, month=may, year=1993, volume=104, number=1, preliminary={LICS::AlurH1990:390}, abstract={The theory of the natural numbers with linear order and monadic predicates underlies propositional linear temporal logic. To study temporal logics that are suitable for reasoning about real-time systems, we combine this classical theory of infinite state sequences with a theory of discrete time, via a monotonic function that maps every state to its time. The resulting \emph{theory of timed state sequences} is shown to be decidable, albeit nonelementary, and its expressive power is characterized by $\omega$-regular sets. Several more expressive variants are proved to be highly undecidable. \par This framework allows us to classify a wide variety of real-time logics according to their complexity and expressiveness. Indeed, it follows that most formalisms proposed in the literature cannot be decided. We are, however, able to identify two elementary real-time temporal logics as expressively complete fragments of the theory of timed state sequences, and we present tableau-based decision procedures for checking validity. Consequently, these two formalisms are well-suited for the specification and verification of real-time systems.}, xxx-references={LICS::AlurCD90, FOCS::AlurH89, LICS::AlurH90, FOCS::AlurH92, LICS::HarelLP90, LICS::Lewis90, McNaughton66, FOCS::Pnueli77, JACM::SistlaC85, Thomas81, Wolper83, FOCS::WolperVS83} } @Article{SekarR93, title={Programming in Equational Logic: Beyond Strong Sequentiality}, author={R. C. Sekar and I. V. Ramakrishnan}, pages={78--109}, journal=iandcomp, month=may, year=1993, volume=104, number=1, preliminary={LICS::SekarR1990:230}, xxx-references={Thatte87} } REGULAR ARTICLE: @Article{Middeldorp93, refkey={C1050}, title={Modular Properties of Conditional Term Rewriting Systems}, author={Aart Middeldorp}, pages={110--158}, journal=iandcomp, month=may, year=1993, volume=104, number=1, abstract={A property of term rewriting systems is called \emph{modular} if it is preserved under disjoint union. For unconditional term rewriting systems several modularity results are known. The aim of this paper is to analyze and extend these results to conditional term rewriting systems. It turns out that conditional term rewriting is much more complicated than unconditional rewriting from a modularity point of view. For instance, we will show that the modularity of weak normalization for unconditional term rewriting systems does not extend to conditional term rewriting systems. On the positive side, we mention the extension of Toyama's confluence result for disjoint unions of term rewriting systems to conditional term rewriting systems.}, remarks={\textbf{Erratum}: Bernhard Gramlich (``On Modularity of Termination and Confluence Properties of Conditional Rewrite Systems,'' \emph{Proc. 4th Int. Conf. on Algebraic and Logic Programming}, Madrid, LNCS 850, pp. 186-203, 1994) provided a counterexample against Theorem 5.2. By a complicated analysis he shows that its two main consequences, Corollary 5.4 and Theorem 5.6, remain valid.}, xxx-references={JCSS::BergstraK86, MISC::Toyama88, CACM::DershowitzM79, ICALP::Dershowitz81, SLP::DershowitzP85, RTA::DershowitzOS87, MICS::DershowitzP87, CADE::DershowitzOS88, HTCS::DershowitzJ90, BOOK::Drosten89, SLP::Fribourg85, THESIS::Geser90, MICS::GoguenM86, FDPC::JouannaudW86, TCS::Kaplan84, JSYMC::Kaplan87, MISC::KaplanR89, HLCS::Klop91, IPL::KuriharaK90, TR::KuriharaO90, RTA::Middeldorp89, LICS::Middeldorp89, CTRS::Middeldorp90, THESIS::Middeldorp90, RTA::MiddeldorpT91, ANM::Newman42, IPL::Rusinowitch87, JACM::Toyama87, IPL::Toyama87a, MISC::Toyama88, RTA::ToyamaKB89, RTA::ZangR85} } June 1993 Volume 104, Number 2 @Article{FeldmanINNRS93, title={On Dice and Coins: Models of Computation for Random Generation}, author={David Feldman and Russell Impagliazzo and Moni Naor and Noam Nisan and Steven Rudich and Adi Shamir}, pages={159--174}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={FOCS::KarpL83} } @Article{IsraeliJ93, title={Uniform Self-Stabilizing Ring Orientation}, author={Amos Israeli and Marc Jalfon}, pages={175--196}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={STOC::Angluin80, JACM::AttiyaSW88, ItaiR90} } @Article{Frederickson93, title={An Optimal Algorithm for Selection in a {Min-Heap}}, author={Greg N. Frederickson}, pages={197--214}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, abstract={An $O(k)$-time algorithm is presented for selecting the $k$-th smallest element in a binary min-heap of size $n \gg k$. The approach uses recursively-defined data structures that impose a hierarchical grouping on certain elements in the heap. The result establishes a further example of a partial order for which the $k$-th smallest element can be determined in time proportional to the information theory lower bound. Two applications, to a resource allocation problem and to the enumeration of the $k$ smallest spanning trees, are identified.}, xxx-references={STOC::BentJ85, STOC::Frederickson90} } @Article{ShyamasundarNP93, title={Semantics of Nondeterministic Asynchronous Broadcast Networks}, author={R. K. Shyamasundar and K. T. Narayana and T. Pitassi}, pages={215--252}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={KoymansSRGA88} } @Article{LuginbuhlL93, title={Hierarchies and Space Measures for Pointer Machines}, author={David R. Luginbuhl and Michael C. Loui}, pages={253--270}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, abstract={We present two definitions of space complexity for Sch\"onhage's pointer machine (PM): a uniform measure, {\em mass}, and a logarithmic measure, {\em capacity}. We consider how each space measure affects the time and space relationships between pointer machines and the more classical models of computation. For example, we show that a Turing machine of space complexity $s$ can be simulated by a pointer machine of mass complexity $O(s/\!\log s)$ in real time. This is an improvement of a result of van Emde Boas. \par We show that space compression is possible for pointer machines, and we show that the time and space hierarchies for pointer machines are tight. We also present a simulation of an alternating pointer machine of time complexity $t$ by a deterministic pointer machine of mass complexity $O(t/\!\log t)$.}, xxx-references={JACM::ChandraKS81, FOCS::DymondC80, JACM::HartmanisH71, FOCS::StearnsHL65, JACM::LeongS81, SlotB88} } @Article{KannanVVY93, title={A Circuit-Based Proof of {Toda's} Theorem}, author={Ravi Kannan and H. Venkateswaran and V. Vinay and Andrew C. Yao}, pages={271--276}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={FOCS::Allender89, FOCS::Toda89} } @Article{DurisG93, title={On the Power of Multiple Reads in a Chip}, author={Pavol {\v{D}}uri{\v{s}} and Zvi Galil}, pages={277--287}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={DurisGS87, STOC::KarchmerW88, FOCS::KedemZ81, STOC::Yao81} } @Article{GoldsmithJY93, title={Using Self-Reducibilities to Characterize Polynomial Time}, author={Judy Goldsmith and Deborah Joseph and Paul Young}, pages={288--308}, journal=iandcomp, month=jun, year=1993, volume=104, number=2, xxx-references={JACM::BalcazarBS86, Book74, HartmanisIS85, STOC::KarpL80, STOC::Krentel86, Selman82} } Author Index for Volume 104 -- pages 309--310 July 1993 Volume 105, Number 1 @Article{ReynoldsP93, title={On Functors Expressible in the Polymorphic Typed Lambda Calculus}, author={John C. Reynolds and Gordon D. Plotkin}, pages={1--29}, journal=iandcomp, month=jul, year=1993, volume=105, number=1, xxx-references={LICS::AmadioBL86, AmericaBKR89, LICS::Coquand88, CoquandGW89, LICS::FreydS87, JACM::GoguenTWW77, Gunter87, LICS::GunterJ88, FOCS::Leivant83, LICS::Pitts89, JACM::Reynolds77} } @Article{Jutting93, title={Typing in Pure Type Systems}, author={L. S. van Benthem Jutting}, pages={30--41}, journal=iandcomp, month=jul, year=1993, volume=105, number=1 } @Article{Hoofman93, title={Continuous Information Systems}, author={R. Hoofman}, pages={42--71}, journal=iandcomp, month=jul, year=1993, volume=105, number=1 } @Article{GasarchHH93, title={On Checking Versus Evaluation of Multiple Queries}, author={William I. Gasarch and Lane A. Hemachandra and Albrecht Hoene}, pages={72--93}, journal=iandcomp, month=jul, year=1993, volume=105, number=1, abstract={The plausibility of {\em computing\/} the answers to many membership queries to a hard set with few queries is the subject of the theory of terseness. In this paper, we develop companion theories---both complexity-theoretic and recursion-theoretic---of {\em characteristic vector terseness}. These theories ask whether the answers to many membership queries to a hard set can be {\em checked\/} with fewer queries.}, references={IC::AmirG1988:37, JACM::AllenderH1992, SICOMP::AllenderR1988, SOVMD::Barzdins1968, TR::SitharamY1989, SICOMP::BalcazarBS1986, TCS::Beigel1991, SCTC::Beigel1987, TR::Beigel1988, IC::BlassG1982:80, IC::BeigelGGO1993:68, SICOMP::BakerGS1975:431, JCSS::Cai1989, SICOMP::CaiGHHSWW1988:1232, SICOMP::CaiGHHSWW1989:95, MST::CaiH1990, SCTC::Chang1989, SCTC::ChangK1990, TR::ChangK1990, SICOMP::CaiM1987, LNM::EpsteinK1981, SICOMP::Gill1977, TCS::GoldschlagerP1986, CAI::GundermannW1987, MISC::Hausdorff1914, JCSS::Hemachandra1989, BOOK::HopcroftU1979, FOCS::ImpagliazzoT1989, TAMS::Jockusch1968, MISC::Jockusch1979, CFSTTCS::Kamper1988, SICOMP::Kadin1988, SICOMP::KoS1985, RAIRO::KoblerW1987, JCSS::PapadimitriouY1984, GICTCS::PapadimitriouZ1983, BOOK::Rogers1967, THESIS::Rubinstein1988, TR::Rubinstein1990, JCSS::Schoning1983, TCS::Stockmeyer1976, IPL::Valiant1976, SCTC::Wagner1988, SICOMP::Wagner1990} } @Article{JungKS93, title={Lower Bounds and Efficient Algorithms for Multiprocessor Scheduling of Directed Acyclic Graphs with Communication Delays}, author={Hermann Jung and Lefteris M. Kirousis and Paul Spirakis}, pages={94--104}, journal=iandcomp, month=jul, year=1993, volume=105, number=1, xxx-references={FOCS::PapadimitriouU84, STOC::PapadimitriouY88} } @Article{Ristad93, refkey={C1011}, title={The Anaphora Problem}, author={Eric Sven Ristad}, pages={105--131}, journal=iandcomp, month=jul, year=1993, volume=105, number=1, abstract={Consider the computational problem of understanding the utterances of a human language that contain pronouns. In order to completely understand such utterances, the language user must determine the intended reference of each pronoun in a given utterance. For example, in order to comprehend the English sentence ``Jocasta loved her son,'' the hearer might determine that the possessive pronoun ``her'' and the proper noun ``Jocasta'' both refer to Jocasta, the Queen of Thebes. Using such facts of linguistic knowledge, we develop a sophisticated formal model of this computational problem and prove that it is NP-complete. This result is the first empirically-plausible bound on the computational complexity of human language. No knowledge of linguistic theory is needed to understand our analysis, only knowledge of English.}, references={BOOK::Canny1988, LINGI::Chomsky1980, BOOK::Chomsky1981, BOOK::Chomsky1986, BOOK::Dudeney1967, BOOK::Emmet1972, BOOK::Fujimura1978, LINGI::Higginbotham1983, LINGI::Higginbotham1985, LINGA::Lasnik1976, JLINGR::Lasnik1981, MISC::Lasnik1989, FOCS::Reif1979:421, FOCS::ReifS1985:144, BOOK::Ristad1993} } @Article{Chaudhuri93, title={More {\em Choices\/} Allow More {\em Faults\/}: Set Consensus Problems in Totally Asynchronous Systems}, author={Soma Chaudhuri}, pages={132--158}, journal=iandcomp, month=jul, year=1993, volume=105, number=1, abstract={We define the $k$-\emph{set consensus problem} as an extension of the consensus problem, where each processor decides on a single value such that the set of decided values in any run is of size at most $k$. We require the \emph{agreement} condition that all values decided upon are initial values of some processor. We show that the problem has a simple $(k - 1)$-resilient protocol in a totally asynchronous system. In an attempt to come up with a matching lower bound on the number of failures, we study the \emph{uncertainty} condition, which requires that there must be some initial configuration from which all possible input values can be decided. We prove using a combinatorial argument that any $k$-resilient protocol for the $k$-set agreement problem would satisfy the uncertainty condition, while this is not true for any $(k - 1)$-resilient protocol. This result seems to strengthen the conjecture that there is no $k$-resilient protocol for this problem. We prove this result for a restricted class of protocols. Our motivation for studying this problem is to test whether the number of \emph{choices} allowed to the processors is related to the number of \emph{faults}. We hope that this will provide intuition towards achieving better bounds for more practical problems that arise in distributed computing, \emph{e.g.}, the renaming problem. The larger goal is to characterize the boundary between possibility and impossibility in asynchronous systems given multiple faults.}, remarks={A preliminary version of this paper appears in \emph{ACM Proceedings of the Ninth ACM Symposium on Principles of Distributed Computing}, August 1990. \par The main conjecture in this paper was solved by three independent teams of researchers (Borowsky & Gafni, Herlihy & Shavit, Saks & Zaharoglou) in 1993. Their work appeared as three separate papers in STOC'93.}, xxx-references={FOCS::AttiyaBDKPR87, STOC::Bracha85, FOCS::DolevDS83, JACM::DolevDS87, JACM::FischerLP85, FOCS::Rabin83} } August 1993 Volume 105, Number 2 @Article{AbramskyO93, title={Full Abstraction in the Lazy Lambda Calculus}, author={Samson Abramsky and C.-H. Luke Ong}, pages={159--267}, journal=iandcomp, month=aug, year=1993, volume=105, number=2, xxx-references={Abramsky91, LICS::Bloom88, JACM::HennessyM85, Koymans82, LICS::Meyer88, Meyer82, FOCS::Ong88, Statman85} } @Article{Goldberg93, title={Automating {P\'olya} Theory: The Computational Complexity of the Cycle Index Polynomial}, author={Leslie Ann Goldberg}, pages={268--288}, journal=iandcomp, month=aug, year=1993, volume=105, number=2 } Author Index for Volume 105 -- page 289 September 1993 Volume 106, Number 1 @Article{RivestS93b, title={On Choosing between Experimenting and Thinking when Learning}, author={Ronald L. Rivest and Robert H. Sloan}, pages={1--25}, journal=iandcomp, month=sep, year=1993, volume=106, number=1, xxx-references={BlumB75, Gold67, Kugel77, Wyner72a} } @Article{Palmgren93, refkey={C1005}, title={An Information System Interpretation of {Martin-L\"of's} Partial Type Theory with Universes}, author={Erik Palmgren}, pages={26--60}, journal=iandcomp, month=sep, year=1993, volume=106, number=1, xxx-references={LICS::AmadioBL86, CoquandGW89, LarsenW91} } @Article{Choffrut93, title={On the Starheight of Some Rational Subsets Closed under Partial Commutations}, author={Christian Choffrut}, pages={61--82}, journal=iandcomp, month=sep, year=1993, volume=106, number=1, xxx-references={DejeanS66, Hashiguchi82, Hashiguchi88, McNaughton67} } @Article{LeungW93, title={Minimizing the Number of Late Tasks with Error Constraint}, author={Joseph Y.-T. Leung and C. S. Wong}, pages={83--108}, journal=iandcomp, month=sep, year=1993, volume=106, number=1 } @Article{AptP93, title={Reasoning about Termination of Pure Prolog Programs}, author={Krzysztof R. Apt and Dino Pedreschi}, pages={109--157}, journal=iandcomp, month=sep, year=1993, volume=106, number=1, xxx-references={LICS::Baudinet88, JACM::Shostak77, JACM::UllmanG88} } October 1993 Volume 106, Number 2 @Article{CoriMZ93, title={Asynchronous Mappings and Asynchronous Cellular Automata}, author={Robert Cori and Yves M{\'e}tivier and Wies{\l}aw Zielonka}, pages={159--202}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, xxx-references={BertoniMS89, JACM::BrookesHR84} } @Article{KawaguchiW93, title={New Results in Graph Routing}, author={Kimio Kawaguchi and Koichi Wada}, pages={203--233}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, xxx-references={BroderDFS87, DolevHSS87, STOC::Feldman85, PelegS87} } @Article{Baeza-YatesCR93, title={Searching in the Plane}, author={Ricardo A. {Baeza-Yates} and Joseph C. Culberson and Gregory J. E. Rawlins}, pages={234--252}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, abstract={In this paper we initiate a new area of study dealing with the best way to search a possibly unbounded region for an object. The model for our search algorithms is that we must pay costs proportional to the distance of the next probe position relative to our current position. This model is meant to give a realistic cost measure for a robot moving in the plane. We also examine the effect of decreasing the amount of {\em a priori\/} information given to search problems. Problems of this type are very simple analogues of non-trivial problems on searching an unbounded region, processing digitized images, and robot navigation. We show that for some simple search problems, the relative information of knowing the general direction of the goal is much higher than knowing the distance to the goal.}, xxx-references={STOC::BorodinLS87, FOCS::KarpSW86} } @Article{HowellJR93, refkey={C1173}, title={Completeness Results for Single-Path {Petri} Nets}, author={Rodney R. Howell and Petr Jan{\v{c}}ar and Louis E. Rosier}, pages={253--265}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, abstract={We define a new subclass of persistent Petri nets called single-path Petri nets. Our intention is to provide a class of Petri nets whose study might yield some insight into the mathematical properties of persistent Petri nets or even general Petri nets. We conjecture that the Karp-Miller coverability tree for a persistent net is small enough to be searched in polynomial space. Although we are unable to prove this conjecture, we do show that single-path Petri nets have this property. We then use this fact to show that the canonical analysis problems (i.e., boundedness, reachability, containment, and equivalence) for single-path Petri nets are PSPACE-complete in the strong sense. Furthermore, we show that the problem of recognizing a single-path Petri net is also PSPACE-complete.}, xxx-references={STOC::CardozaLM76, STOC::Huynh85, STOC::Kosaraju82, JACM::LandweberR78, JACM::MayrM81, STOC::Mayr81} } @Article{BerkmanV93, title={On Parallel Integer Merging}, author={Omer Berkman and Uzi Vishkin}, pages={266--285}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, xxx-references={BhattDHPRS91, ColeV86, Hagerup87, FOCS::HeideW85, JACM::Tarjan75} } @Article{Meiser93, title={Point Location in Arrangements of Hyperplanes}, author={S. Meiser}, pages={286--303}, journal=iandcomp, month=oct, year=1993, volume=106, number=2, xxx-references={STOC::Clarkson85, JACM::Heide84} } Author Index for Volume 106 -- page 304 November 1993 Volume 107, Number 1 @Article{GoodrichAO93, title={Output-Sensitive Methods for Rectilinear Hidden Surface Removal}, author={Michael T. Goodrich and Mikhail J. Atallah and Mark H. Overmars}, pages={1--24}, journal=iandcomp, month=nov, year=1993, volume=107, number=1, preliminary={icalp::GoodrichAO1990:689}, references={STOC::Chazelle1984, STOC::GabowT1983, FOCS::OvermarsS1989} } @Article{OHearnT93, title={Semantical Analysis of Specification Logic, 2}, author={P. W. O'Hearn and R. D. Tennent}, pages={25--57}, journal=iandcomp, month=nov, year=1993, volume=107, number=1, abstract={The ``specification logic'' of J.~C.~Reynolds (\emph{in} ``Tools and Notions for Program Construction'' (D. N\'eel, Ed.), pp. 121--161, Cambridge Univ. Press, Cambridge, 1982) is a formal system for proving partial-correctness properties of programs in an Algol-like language with higher-order procedures. In a previous publication (Tennent, \emph{Inform.\ and Comput.}\ \textbf{85}, 135--162 (1990)), a model was presented that validates all axioms of the system {\em except\/} those involving non-interference formulas for {\em procedural\/} phrases. Following Reynolds, non-interference for procedural phrases was there defined {\em syntactically}, by induction on types. Here, we present a new {\em semantic\/} interpretation of non-interference (for phrases of {\em arbitrary\/} type) which is equivalent to the interpretation given earlier for phrases of basic type. This interpretation provides the first model for {\em all\/} of Reynolds's axioms (except the equivalences formerly used to define procedural non-interference). A slightly more refined model is used to validate also a new axiom which formalizes a method used by (``The Craft of Programming,'' Prentic-Hall, London, 1981) to reason about programs with multiple levels of abstraction.}, references={ACTAI::BarringerCJ1984:251, LP::ClarkeK1983, ACTAI::DammJ1983, IC::GermanCH1989:265, LP::Goerdt1985, CACM::Hoare1969:576, SSAL::Hoare1971, MISC::Milner1972, MISC::MilnerN1975, POPL::MeyerS1988, THESIS::OHearn1990, LP::Olderog1984, TCS::Olderog1984, THESIS::Oles1982, MISC::Oles1985, LP::Parikh1985, MISC::Plotkin1980, POPL::Reynolds1978, BOOK::Reynolds1981, MISC::Reynolds1981, MISC::Reynolds1982, LP::Sieber1985, IC::Statman1985:85, MISC::Statman1990, MISC::Tennent1986, IPL::Tennent1987, IC::Tennent1990:135, TCS::TennentT1991} } @Article{Parrow93, title={Structural and Behavioural Equivalences of Networks}, author={Joachim Parrow}, pages={58--90}, journal=iandcomp, month=nov, year=1993, volume=107, number=1, preliminary={icalp::Parrow1990:540}, references={BergstraK1984:109, JACM::BrookesHR1984, JACM::Milner1979, JACM::StaplesN1985} } @Article{PacholskiS93, title={A Counterexample to the 0-1 Law for the Class of Existential Second-Order Minimal {G\"odel} Sentences with Equality}, author={Leszek Pacholski and Wies{\l}aw Szwast}, pages={91--103}, journal=iandcomp, month=nov, year=1993, volume=107, number=1, xxx-references={STOC::KolaitisV87, KolaitisV90, LICS::PacholskiS91} } @Article{Kuper93, title={An Axiomatic Theory for Partial Functions}, author={Jan Kuper}, pages={104--150}, journal=iandcomp, month=nov, year=1993, volume=107, number=1 } @Article{KlarlundS93, title={Proving Nondeterministically Specified Safety Properties Using Progress Measures}, author={Nils Klarlund and Fred B. Schneider}, pages={151--170}, journal=iandcomp, month=nov, year=1993, volume=107, number=1, abstract={Using the notion of progress measures, we give a complete verification method for proving that a program satisfies a property specified by an automaton having bounded nondeterminism. Such automata can express any safety property. Previous methods, which can be derived from the method presented here, either rely on transforming the program or are not complete.}, xxx-references={LICS::KlarlundK91, LICS::Vardi87} } December 1993 Volume 107, Number 2 @Article{BurnsL93, title={Bounds on Shared Memory for Mutual Exclusion}, author={James E. Burns and Nancy A. Lynch}, pages={171--184}, journal=iandcomp, month=dec, year=1993, volume=107, number=2, xxx-references={FOCS::Burns81, JACM::BurnsJLFP82, JACM::Lamport86a, JACM::Lamport86b} } @Article{Devolder93, refkey={C1102}, title={Precircular Codes and Periodic Biinfinite Words}, author={Jeanne Devolder}, pages={185--201}, journal=iandcomp, month=dec, year=1993, volume=107, number=2 } @Article{HennessyI93, title={A Theory of Communicating Processes with Value Passing}, author={M. Hennessy and A. Ing{\'o}lfsd{\'o}ttir}, pages={202--236}, journal=iandcomp, month=dec, year=1993, volume=107, number=2, xxx-references={JACM::Hennessy85} } @Article{FreivaldsS93, title={On the Role of Procrastination in Machine Learning}, author={R{\=u}si\c{n}\u{s} Freivalds and Carl H. Smith}, pages={237--271}, journal=iandcomp, month=dec, year=1993, volume=107, number=2, abstract={The traditional model of inductive inference is enhanced to allow the learning machines to procrastinate about how many trials they will need to complete an inference or about how accurate their solution will be. Hierarchies of classes of learnable phenomena (represented by sets of recursive functions) isomorphic to the structure of the constructive ordinals are revealed. The existence of such hierarchies indicates a potential advantage of procrastination as a learning technique. Tradeoffs between the two types of procrastination are shown to not exist in general. One of the new classes of sets of inferrible functions introduced in this paper turns out to have the somewhat unusual property of being closed under finite unions. A new technique, based on a hardest to learn set (relative to a class), is used.}, xxx-references={BlumB75, DaleyS86, FreivaldsSV89, Gold67, Royer86, JACM::Smith82} } @Article{JonssonP93, title={Deciding Bisimulation Equivalences for a Class of {Non-Finite-State} Programs}, author={Bengt Jonsson and Joachim Parrow}, pages={272--302}, journal=iandcomp, month=dec, year=1993, volume=107, number=2, xxx-references={JACM::BrookesHR84, JACM::JonesM77, KanellakisS90, LICS::VardiW86} } @Article{GunterGM93, title={Computing {ML} Equality Kinds Using Abstract Interpretation}, author={Carl A. Gunter and Elsa L. Gunter and David B. MacQueen}, pages={303--323}, journal=iandcomp, month=dec, year=1993, volume=107, number=2 } Author Index for Volume 107 -- page 324 Cumulative Subject Index for Volumes 102--107 -- pages 325--334 January 1994 Volume 108, Number 1 @Article{Tulipani94, title={Decidability of the Existential Theory of Infinite Terms with Subterm Relation}, author={Sauro Tulipani}, pages={1--33}, journal=iandcomp, month=jan, year=1994, volume=108, number=1, abstract={We examine the problem of solving equations, disequations and atomic formulas built on the subterm relation in algebras of rational and infinite terms (trees). We prove that this problem is decidable for any such algebra in a finite signature $S$ with possible new free constants. Moreover, even in presence of subterm relation, the existential theory of rational trees is the same as the existential theory of infinite trees. We leave out the easier case where $S$ has no symbols of arity greater than one. When $S$ has only a symbol of arity greater than one, the decision procedure is different in case that the algebra of rational or infinite, trees contains new free constants or not.}, xxx-references={MISC::Clark78, FGCS::Colmerauer84, JSYMC::ComonL89, MISC::Comon90, IJFCS::Comon90, TCS::Courcelle85, PROAM::Davis72, JLOGP::Fitting85, ACTAI::GuttagH78, THESIS::Huet76, MISC::JouannaudK80, JLOGP::Kunen87, BOOK::Lloyd87, LICS::Maher88, MISC::MaherS90, SOVMD::Malcev61, MISC::Malcev71, JAML::MarongiuT89, MISC::McCarthy77, JACM::Oppen80, HML::Rabin77, TR::Treinen90, FSTTCS::Treinen90, JACM::Venkataraman87, JCSS::VenkataramanYH83} } @Article{BodlaenderMW94, title={The Distributed Bit Complexity of the Ring: From the Anonymous to the Non-anonymous Case}, author={Hans L. Bodlaender and Shlomo Moran and Manfred K. Warmuth}, pages={34--50}, journal=iandcomp, month=jan, year=1994, volume=108, number=1, abstract={In Moran and Warmuth (1993, \emph{SIAM J. Comput.} \textbf{22}, No.~2, 379--399), it was shown that computing any non-constant function on a ring of $n$ processors requires $\Omega(n \log n)$ bits and this bound is tight. This model assumes that all the processors in the ring are identical (anonymous), i.e., all processors run the same program and the only parameter of the program is the input to the processor. In a relaxed model the anonymity is broken by providing each processor with a distinct identity which becomes a second parameter of the program that is executed by all processors. If the set of possible identities grows doubly exponential in $n$, then by a reduction to the anonymous case one can show that the lower bound holds as well. In this paper we show that the lower bound of $\Omega(n \log n)$ bits for computing any non-constant function holds even if the set of possible identities is ``very small'', that is, of size $n^{1+\epsilon}$, for any positive $\epsilon$.}, xxx-references={JACM::AttiyaSW88, FOCS::DurisG87, MansourZ87, JACM::PachlKR84} } @Article{Boudol94, title={Lambda-Calculi for (Strict) Parallel Functions}, author={G{\'e}rard Boudol}, pages={51--127}, journal=iandcomp, month=jan, year=1994, volume=108, number=1, abstract={We introduce two $\lambda$-calculi and show that they are expressive for two canonical domains of parallel functions. The first calculus is an enrichment of the lazy, call-by-name $\lambda$-calculus with call-by-value abstractions and parallel composition, while in the second the usual call-by-name abstractions are disallowed. The corresponding domains are respectively Abramsky's domain $D=(D\rightarrow D)_\bot$, a lifted function space, and $D=(D\rightarrow_\bot D)_\bot$, a lifted domain of strict functions. These domains are lattices, and we show that the parallelism is adequately represented by the join operator, while call-by-value abstractions correspond to strict functions. The proofs of the results rely on a completeness theorem for the logical presentation of the semantics.}, xxx-references={LICS::Abramsky87, AbramskyO93, Bloom90, LICS::CosmadakisMR90, LICS::Meyer88, FOCS::Ong88} } @Article{BoerP94, refkey={C1139}, title={Embedding as a Tool for Language Comparison}, author={Frank S. de Boer and Catuscia Palamidessi}, pages={128--157}, journal=iandcomp, month=jan, year=1994, volume=108, number=1, abstract={This paper addresses the problem of defining a formal tool to compare the expressive power of different concurrent constraint languages. We refine the notion of embedding by adding some ``reasonable'' conditions, suitable for concurrent frameworks. The new notion, called \emph{modular embedding}, is used to define a preorder among these languages, representing different degrees of expressiveness. We show that this preorder is not trivial (i.e., it does not collapse into one equivalence class) by proving that Flat CP cannot be embedded into Flat GHC, and that Flat GHC cannot be embedded into a language without communication primitives in the guards, while the converses hold.}, xxx-references={TCS::BaetenBK87, CWI::BergstraK86, WDAG::Bouge87, ACTAI::Bouge88, TR::Bouge88, JCOML::ChandraM75, NACLP::BoerP90, TPSD::BoerP91, CONCUR::BoerP91, TCS::Simone85, ESOP::Felleisen90, ALP::GabbrielliL90, NCLP::GaifmanMS89, LICS::GerthCLS88, PODC::Herlihy88, CACM::Landin66, ICLP::Maher87, FOCS::McAllesterPS88, IC::PanangadenS92, ICALP::PanangadenS88, PARLE::Parrow89, CSPC::PatersonH70, CACM::Reynolds70, MISC::Reynolds81, THESIS::Saraswat92, POPL::SaraswatR90, ACMCS::Shapiro89, STOC::Shapiro91, CONCUR::Shapiro92, POPL::Stark90, TR::SteeleS76, MISC::ueda87, MISC::Vaandrager92} } @Article{Krichevsky94, title={Occam's Razor, Partially Specified {Boolean} Functions, String Matching, and Independent Sets}, author={Rafail E. Krichevsky}, pages={158--174}, journal=iandcomp, month=jan, year=1994, volume=108, number=1, xxx-references={BeckerS88, Krichevsky84} } February 1, 1994 Volume 108, Number 2 @Article{Shinohara94, title={Rich Classes Inferable from Positive Data: Length-Bounded Elementary Formal Systems}, author={Takeshi Shinohara}, pages={175--186}, journal=iandcomp, month={1~} # feb, year=1994, volume=108, number=2, xxx-references={STOC::Angluin79, Angluin80, Gold67} } @Article{Baeza-YatesG94, title={Fast String Matching with Mismatches}, author={Ricardo A. Baeza-Yates and Gaston H. Gonnet}, pages={187--199}, journal=iandcomp, month={1~} # feb, year=1994, volume=108, number=2, abstract={We describe and analyze three simple and fast algorithms on the average for solving the problem of string matching with a bounded number of mismatches. These are the naive algorithm, an algorithm based on the Boyer-Moore approach, and ad-hoc deterministic finite automata searching. We include simulation results that compare these algorithms to previous works.}, xxx-references={SICOMP::Abrahamson87, CACM::BoyerM77, JACM::Brzozowski64, SPE::Baeza-Yates89, THESIS::Baeza-Yates89, WADS::Baeza-Yates89, SIGIR::Baeza-YatesG89, BOOK::GonnetB91, SIGACT::GalilG86, IPL::GrossiL89, SICOMP::KnuthMP77, TCS::LandauV86, SPE::Smit82, SWAT::TarhioU90} } @Article{HaastadWWY94, title={Optimal Depth, Very Small Size Circuits for Symmetric Functions in {$AC^0$}}, author={Johan H{\aa}stad and Ingo Wegener and Norbert Wurm and Sang-Zin Yi}, pages={200--211}, journal=iandcomp, month={1~} # feb, year=1994, volume=108, number=2, abstract={It is well known which symmetric Boolean functions can be computed by constant depth, polynomial size, unbounded fan-in circuits, i.e., which are contained in the complexity class~$AC^0$. This result is sharpened. Symmetric Boolean functions in~$AC^0$ can be computed by unbounded fan-in circuits with the following properties. If the optimal depth of $AC^0$-circuits is $d$, the depth is at most $d+2$, the number of wires is almost linear, namely $n\log^{O(1)} n$, and the number of gates is subpolynomial (but superpolylogarithmic), namely $2^{O(\log^\delta n)}$ for some $\delta < 1$.}, xxx-references={STOC::AjtaiB84, STOC::Boppana84, STOC::ChandraFL83a, DenenbergGS86, STOC::DolevDPW83, FOCS::Friedman84, STOC::Hastad86} } @Article{LittlestoneW94, title={The Weighted Majority Algorithm}, author={Nick Littlestone and Manfred K. Warmuth}, pages={212--261}, journal=iandcomp, month={1~} # feb, year=1994, volume=108, number=2, xxx-references={JACM::BlumerEHW89, FreivaldsSV89, FOCS::LittlestoneW89, JACM::Pitt89, PittS88} } @Article{BruschiPS94, title={On the Existence of Minimum Asynchronous Automata and on the Equivalence Problem for Unambiguous Regular Trace Languages}, author={Danilo Bruschi and Giovanni Pighizzini and Nicoletta Sabadini}, pages={262--285}, journal=iandcomp, month={1~} # feb, year=1994, volume=108, number=2 } Author Index for Volume 108 -- page 286 February 15/March 1994 Volume 109, Numbers 1 and 2 Special Issue: Selections from International Conference on Theoretical Aspects of Computer Software (TACS'91) @Article{Dezani-Ciancaglini94, title={Preface}, author={Mariangiola Dezani-Ciancaglini}, pages={1--3}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2} } @Article{CardelliMMS94, title={An Extension of System {$F$} with Subtyping}, author={Luca Cardelli and Simone Martini and John C. Mitchell and Andre Scedrov}, pages={4--56}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={System $F$ is a well-known typed $\lambda$-calculus with polymorphic types, which provides a basis for polymorphic programming languages. We study an extension of $F$, called $F_{<:}$ (pronounced {\em ef-sub\/}), that combines parametric polymorphism with subtyping. The main focus of the paper is the equational theory of $F_{<:}$, which is related to PER models and the notion of parametricity. We study some categorical properties of the theory when restricted to closed terms, including interesting categorical isomorphisms. We also investigate proof-theoretical properties, such as the conservativity of typing judgments with respect to $F$. We demonstrate by a set of examples how a range of constructs may be encoded in $F_{<:}$. These include record operations and subtyping hierarchies that are related to features of object-oriented languages.}, xxx-references={BruceL90, Cardelli88, Cosmo95} } @Article{CurienG94, title={Decidability and Confluence of {$\beta\eta\hbox{top}_\le$} Reduction in {${\bf F}_\le$}}, author={Pierre-Louis Curien and Giorgio Ghelli}, pages={57--114}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={We contribute to the syntactic study of ${\bf F}_\le$, a variant of second-order $\lambda$-calculus $\bf F$ which appears as a paradigmatic kernel language for polymorphism and subtyping. The type system of ${\bf F}_\le$ has a maximum type Top and bounded quantification. We endow this language with the $\beta$-rules (for terms and types), to which we add $\eta$-rules (for terms and types) and a rule which equates all terms of type Top. These rules are suggested by the axiomatization of cartesian closed categories. We exhibit a weakly normalizing and confluent reduction system for this theory $\beta\eta {\rm top}_\le$, and show that it is decidable. It is also confluent, but decidability does not follow from confluence, since reduction is not effective. Our proofs rely on the confluence and decidability of a corresponding system on ${\bf F}_1$ (the extension of ${\bf F}$ with a terminal type).}, xxx-references={Breazu-TannenCGS91, BruceL90} } @Article{GianniniR94, title={A Type Inference Algorithm for a Stratified Polymorphic Type Discipline}, author={Paola Giannini and Simona {Ronchi Della Rocca}}, pages={115--173}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, remarks={No Abstract.}, xxx-references={FOCS::Boehm85, LICS::GianniniR88, KfouryTU93, KfouryT92, Mitchell88, JACM::Robinson65} } @Article{Hayashi94, title={Singleton, Union and Intersection Types for Program Extraction}, author={Susumu Hayashi}, pages={174--210}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={Two type theories, ATT and ATTT, are introduced. ATT is an impredicative type theory closely related to the polymorphic type theory of implicit typing of MacQueen et al. ATTT is another version of ATT that extends the Girard-Reynolds second order lambda calculus. ATT has notions of intersection, union and singleton types. ATTT has a notion of refinement types as in the type system for ML by Freeman and Pfenning, plus intersection and union of refinement types and singleton refinement types. We will show how singleton, union and intersection types serve for development of programs without unnecessary codes via a variant of the Curry-Howard isomorphism. More exactly, they give a way to write types as specifications of programs without unnecessary codes which is inevitable in the usual Curry-Howard isomorphism.}, xxx-references={BruceMM90, LICS::Coquand86, CoquandH88, MacQueenPS86} } @Article{Phoa94, title={From Term Models to Domains}, author={Wesley Phoa}, pages={211--255}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={Let {\tt B} be the closed term model of the $\lambda$-calculus in which terms with the same B\"ohm tree are identified. We investigate which partial equivalence relations (PERs) on {\tt B} can be regarded as predomains or domains. Working inside the realizability topos on {\tt B}, such PERs can be regarded simply as sets in a particular model of constructive set theory. \par No well-behaved partial order has been identified for any class of PERs; but it is still possible to isolate those PERs which have `suprema of chains' in a certain sense, and all maps between such PERs in the model preserve such suprema of chains. One can also define what it means for such a PER to have `bottom'; partial function spaces provide an example. For these PERs, fixed points of arbitrary endofunctions exist and are computed by the fixed point combinator {\tt y}. \par The categories of predomains are closed under the formation of total and partial function spaces, polymorphic types and convex powerdomains. They in fact form reflective subcategories of the realizability topos; and in this set-theoretic context, these constructions are very simple to describe. \par We illustrate the theory by discussing an interpretation of PCF, and proving a computational adequacy theorem. None of the usual conterexamples to full abstraction are applicable to our model.}, xxx-references={LICS::AbadiP90, Amadio91, LICS::FreydMRS90, LICS::Phoa90, LICS::Robinson89} } @Article{Plotkin94, title={A Semantics for Static Type Inference}, author={Gordon Plotkin}, pages={256--299}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={Curry's system for F-deducibility is the basis for static type inference algorithms for programming languages such as ML\@. If a natural ``preservation of types by conversion'' rule is added to Curry's system, it becomes undecidable, but complete relative to a variety of model classes. We show completeness for Curry's system itself, relative to an extended notion of model that validates reduction but not conversion. Two proofs are given: one uses a term model and the other a model built from type expressions. Extensions to systems with polymorphic or intersection types are also considered.}, xxx-references={CardoneC91, MacQueenPS86, Mitchell88, LICS::Seely87, Yokouchi95} } @Article{Abadi94, title={A Semantics for Static Type Inference in a Nondeterministic Language}, author={Mart{\'\i}n Abadi}, pages={300--306}, journal=iandcomp, month={15~} # feb # {/} # mar, year=1994, volume=109, number={1/2}, abstract={Plotkin used the models of reduction in order to obtain a semantic characterization of static type inference in the pure $\lambda$-calculus. Here we apply these models to the study of a nondeterministic language, obtaining results analogous to Plotkin's.}, xxx-references={Boudol94, Plotkin94} } Author Index for Volume 109 -- page 307 April 1994 Volume 110, Number 1 @Article{Sorenson94, title={Polylog Depth Circuits for Integer Factoring and Discrete Logarithms}, author={Jonathan Sorenson}, pages={1--18}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={In this paper, we develop parallel algorithms for integer factoring and for computing discrete logarithms. In particular, we give polylog depth probabilistic boolean circuits of subexponential size for both of these problems, thereby solving an open problem of Adleman and Kompella. \par Existing sequential algorithms for integer factoring and discrete logarithms use a \emph{prime base} which is the set of all primes up to a bound~$B$. We use a much smaller value for~$B$ for our parallel algorithms than is typical for sequential algorithms. In particular, for inputs of length~$n$, by setting $B = n^{\log^dn}$ with $d$ a positive constant, we construct \begin{itemize} \item Probabilistic boolean circuits of depth $O(\log^{2d+2}n)$ and size $\exp\left[O\left(n/\log^d n\right)\right]$ for completely factoring a positive integer with probability $1-o(1)$, and \item Probabilistic boolean circuits of depth $O(\log^{2d+2}n+\log^3n)$ and size $\exp\left[O\left(n/\log^dn\right)\right]$ for computing discrete logarithms in the finite field $GF(p)$ for $p$ a prime with probability $1-o(1)$. \end{itemize} These are the first results of this type for both problems.}, xxx-references={FOCS::Adleman79, STOC::Adleman91, STOC::AdlemanK88, BorodinCP83, BorodinGH82, JACM::FichT88, STOC::LenstraLMP90, STOC::PanR85, SorensonP94} } @Article{ThanischLN94, title={Finding Compact Scheme Forests in Nested Normal Form is {NP}-Hard}, author={P. Thanisch and G. Loizou and J. Nummenmaa}, pages={19--41}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, xxx-references={JACM::BeeriFMY83, JACM::Galil82, JACM::Lien82} } @Article{NgS94, title={Stable Semantics for Probabilistic Deductive Databases}, author={Raymond Ng and V. S. Subrahmanian}, pages={42--83}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, xxx-references={FaginHM90} } @Article{KuceraMP94, title={On Learning Monotone {DNF} Formulae under Uniform Distributions}, author={Ludek Kucera and Alberto Marchetti-Spaccamela and Marco Protasi}, pages={84--95}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={We show how to learn in polynomial time monotone $d$-term DNF formulae (formulae in disjunctive normal form with at most $d$ terms) using positive examples drawn from a distribution that is a generalization of the uniform distribution.}, xxx-references={FOCS::BermanR87, STOC::BlumerEHW86, STOC::KearnsL88, STOC::KearnsLPV87, STOC::KearnsV89, FOCS::LinialMR88, STOC::Natarajan87, JACM::PittV88} } @Article{TrahanRL94, title={Parallel Random Access Machines with both Multiplication and Shifts}, author={Jerry L. Trahan and Vijaya Ramachandran and Michael C. Loui}, pages={96--118}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={We prove that the class of languages accepted in polynomial time by Parallel Random Access Machines with both multiplication and shifts using exponentially many processors ($PRAM[*,\uparrow,\downarrow]-PTIME$) includes the class of languages accepted in exponential time and polynomial alternations by an alternating Turing machine and is included in $EXPSPACE$. It follows that the class of languages accepted by a PRAM[$*,\uparrow,\downarrow$] in logarithmic time (using polynomially many processors) includes the polynomial hierarchy and is included in $PSPACE$. Thus, a PRAM[$*,\uparrow,\downarrow$] may be more powerful, to within a polynomial in time, than either a PRAM[$*$] or a PRAM[$\uparrow,\downarrow$], since $PRAM[*]-PTIME$ = $PRAM[\uparrow,\downarrow]-PTIME$ = $PSPACE$.}, xxx-references={FOCS::ChandraS76, STOC::FortuneW78, JACM::Goldschlager82, FOCS::HartmanisS74, JACM::LadnerF80, STOC::Simon77} } @Article{HomerW94, title={Immunity of Complete Problems}, author={Steven Homer and Jie Wang}, pages={119--129}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={Two necessary and sufficient conditions for all $E$-complete sets to contain dense $P$ subsets are shown. We then prove that every $\leq^p_m$-hard for $E$ set and its complement contain dense $E \cap UP$ subsets. As a corollary, every $NE$-complete set and its complement contain dense $E \cap UP$ subsets.}, xxx-references={FOCS::Berman76, STOC::Young83} } @Article{KreveldO94, title={Concatenable Structures for Decomposable Problems}, author={Marc J. van Kreveld and Mark H. Overmars}, pages={130--148}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={Given a data structure and an ordering on the objects it contains, we study methods for obtaining a modified data structure that allows for splits and concatenations with respect to that ordering. A general technique will be given, which works for all data structures for decomposable searching problems and order decomposable set problems. Furthermore, the results imply a new method for adding range restrictions to data structures. Applications include e.g.\ a version of an interval tree that allows for splitting and concatenating on the length of the intervals, a version of the $d$-dimensional k-d tree that allows for splitting and concatenating on all coordinates, and a data structure on points in the plane that allows for reporting the convex hull of the points in a given query rectangle.}, xxx-references={JACM::KreveldO93, JACM::WillardL85} } @Article{SteffenI94, title={Characteristic Formulae for Processes with Divergence}, author={Bernhard Steffen and Anna Ing{\'o}lfsd{\'o}ttir}, pages={149--163}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={Characteristic formulae have been introduced by Graf and Sifakis to relate equational reasoning about processes to reasoning in a modal logic, and therefore to allow proofs about processes to be carried out in a logical framework. This work, which concerned {\em finite\/} processes and bisimulation-like {\em equivalences}, has later on been extended to {\em finite state\/} processes and further equivalences. Based upon an intuitionistic understanding of Hennessy-Milner logic (HML) with mutual recursion, we extend these results to cover bisimulation-like {\em preorders}, which are sensitive to liveness properties. This demonstrates the expressive power of intuitionistically interpreted HML with mutual recursion, and it builds the theoretical basis for a uniform and efficient method to {\em automatically verify\/} bisimulation--like relations between processes by means of {\em model checking}.}, xxx-references={GrafS86a, GrafS86b, JACM::HennessyM85, LICS::Walker88} } @Article{DiekertOR94, title={On Confluent Semi-commutations: Decidability and Complexity Results}, author={Volker Diekert and Edward Ochma{\'n}ski and Klaus Reinhardt}, pages={164--182}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={The subject of this paper is the confluence of finite semi-commutation systems. Confluence of such systems is proved to be a decidable property. Existence of a finite complete presentation of a trace monoid using rules only from another given trace monoid is proved to be reducible to the existence of a confluent semi-commutation system. Complexity results related to the preceding problems are proved: deciding the existence of finite complete presentations is $\Sigma_2^P$-complete, whereas deciding confluence of semi-commutation systems is Co-NP-complete. Additionally, an open problem about trace synchronizations is solved: The local checking property is Co-NP-complete. A preliminary version of this paper appeared in the Proceedings of the 1991 International Colloquium on Automata, Languages and Programming, Springer-LNCS 510.}, xxx-references={ClerboutL87} } @Article{AttiyaL94, title={Time Bounds for Real-Time Process Control in the Presence of Timing Uncertainty}, author={Hagit Attiya and Nancy A. Lynch}, pages={183--232}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={A timing-based variant of the \emph{mutual exclusion} problem is considered. In this variant, only an upper-bound, $m$, on the time it takes to release the resource is known, and no explicit signal is sent when the resource is released; furthermore, the only mechanism to measure real time is an inaccurate clock, whose tick intervals take time between two constants, $c_1 \leq c_2$. When control is centralized it is proved that \[ n \left[ c_2 \left( \lfloor (m+l)/c_1\rfloor \right) \right] + l \] is an exact bound on the worst case response time for any such algorithm, where $n$ is the number of contenders for the resource and $l$ is an upper bound on process step time. On the other hand, when control is distributed among processes connected via communication lines with an upper bound, $d$, for message delivery time, it is proved that \[ n \left[ c_2 \left( {\lfloor (m + l)/c_1 \rfloor + 1} \right) + d + c_2 + 2 l \right] \] is an upper bound. A new technique involving \emph{shifting} and \emph{shrinking} executions is combined with a careful analysis of the best allocation policy to prove a corresponding lower bound of \[ n \cdot c_2 (m/c_1) + (n-1) d . \] These combinatorial results shed some light on modeling and verification issues related to real-time systems.}, references={JACM::ArjomandiFL1983, STOC::AttiyaDLS1991, ACCCC::AttiyaM1990, UATR::BaetenB1990, SOSP::BernsteinH1981, IEEETSE::CoolahanR1983, IEEETSE::Dasarathy1985, JCSS::DolevHS1986, IBM::DworkS1991, RTSOS::GerberL1989, JCOMP::HalpernMM1985, IEEETSE::Hasse1981, POPL::HuizingGR1987, IEEETSE::JahanianM1986, IEEETC::JahanianM1987, KoymansSRGA1988:210, CACM::Lamport1978, IEEETSE::LevesonS1987, PODC::Liskov1991:1, WelchL1988:1, FRTCRI::Lynch1988, PODC::LynchA1990, PODC::LynchT1987, CWIQ::LynchT1989, CONCUR::MerrittMT1991, PODC::Ponzio1991, SMTHESIS::Ponzio1991, ICALP::ReedR1986, DC::ShankarL1987, IFIP::Sifakis1977, IBM::SimonsWL1988, LundeliusL1984:190, MISC::ZwaricoLG} } @Article{Zhang94, title={A Representation of {{\bf SFP}}}, author={Guo-Qiang Zhang}, pages={233--263}, journal=iandcomp, month=apr, year=1994, volume=110, number=1, abstract={A sequent structure of Gentzen style entailment with identity, weakening, and cut rules is given and shown to be basic to information systems. A category of strongly finite sequent structures is proved to be equivalent to {\bf SFP}\@. Constructions such as the Plotken powerdomain and the function space are provided, as well as a cpo (complete partial order) of such systems to give meanings to recursively defined domains.}, xxx-references={Gunter87, Hrbacek89, Zhang92}, full-xxx-references={APAL::Abramsky91, TCS::Coquand89, TCS::DrosteG90, MISC::Gallier86, MISC::Gunter85, Gunter87, Hrbacek89, MISC::Johnstone82, TCS::Jung90, MISC::LarsenW84, MISC::MacLane77, SICOMP::Plotkin76, MISC::Scott82, MISC::Smyth83, MISC::Vickers89, TCS::Winskel85, MISC::Zhang91a, MISC::Zhang89, Zhang92, TCS::Zhang89, MISC::Zhang91b} } May 1, 1994 Volume 110, Number 2 Special Issue: Selections from 1991 IEEE Symposium on Logic in Computer Science @Article{Kahn94, refkey={C1568}, title={Preface}, author={Gilles Kahn}, pages={iii}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2 } @Article{BucciarelliE94, refkey={C1461}, title={Sequentiality in an Extensional Framework}, author={Antonio Bucciarelli and Thomas Ehrhard}, pages={265--296}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, preliminary={LICS::BucciarelliE1991:138}, abstract={We present a cartesian closed category of {\em dI-domains with coherence\/} and {strongly stable functions} which provides a new model of PCF, where terms are interpreted by {\em functions\/} and where, at first order, all functions are {\em sequential}. We show how this model can be refined in such a way that the theory it induces on the terms of PCF be strictly finer than the theory of the Scott model of continuous functions.} } @Article{Coquand94, refkey={C1200}, title={An Analysis of {Ramsey's} Theorem}, author={Thierry Coquand}, pages={297--304}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, abstract={We try to show that constructive and intuitionistic mathematics may benefit from the use of concepts and notations developped in computing science. We use here only the simple and basic notion of transition systems, and some elementary lemmas about the eventuality modality, used in the logic of processes. This allows us to give a clear and general formulation of Brouwer's bar theorem. We give as an application an abstract constructive treatment of Ramsey's theorem, which generalizes the statement that Paris and Harrington have shown to be unprovable in Peano arithmetic.}, xxx-references={JACM::Huet80} } @Article{GodefroidW94, refkey={C1462}, title={A Partial Approach to Model Checking}, author={Patrice Godefroid and Pierre Wolper}, pages={305--326}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, preliminary={LICS::GodefroidW1991:406}, abstract={This paper presents a model-checking method for linear-time temporal logic that can avoid most of the state explosion due to the modelling of concurrency by interleaving. The method relies on the concept of Mazurkiewicz's trace as a semantic basis and uses automata-theoretic techniques, including automata that operate on words of ordinality higher than~$\omega$.}, xxx-references={LICS::AlurCD90, LICS::AlurH90, LICS::BurchCMDH90, LICS::Browne86, LICS::EmersonL86, LICS::SistlaG87, LICS::GodefroidW91, LICS::HarelLP90, LICS::PnueliZ86, FOCS::Vardi85, LICS::VardiW86, Wolper83, FOCS::WolperVS83} } @Article{HodasM94, refkey={C1460}, title={Logic Programming in a Fragment of Intuitionistic Linear Logic}, author={Joshua S. Hodas and Dale Miller}, pages={327--365}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, abstract={When logic programming is based on the proof theory of intuitionistic logic, it is natural to allow implications in goals and in the bodies of clauses. Attempting to prove a goal of the form $D \supset G$ from the context (set of formulas) $\Gamma$ leads to an attempt to prove the goal $G$ in the extended context $\Gamma\cup\{D\}$. Thus during the bottom-up search for a cut-free proof contexts, represented as the left-hand side of intuitionistic sequents, grow as stacks. While such an intuitionistic notion of context provides for elegant specifications of many computations, contexts can be made more expressive and flexible if they are based on linear logic. After presenting two equivalent formulations of a fragment of linear logic, we show that the fragment has a goal-directed interpretation, thereby partially justifying calling it a logic programming language. Logic programs based on the intuitionistic theory of hereditary Harrop formulas can be modularly embedded into this linear logic setting. Programming examples taken from theorem proving, natural language parsing, and data base programming are presented: each example requires a linear, rather than intuitionistic, notion of context to be modeled adequately. An interpreter for this logic programming language must address the problem of splitting contexts; that is, when attempting to prove a multiplicative conjunction (tensor), say $G_1\otimes G_2$, from the context $\Delta$, the latter must be split into disjoint contexts $\Delta_1$ and $\Delta_2$ for which $G_1$ follows from $\Delta_1$ and $G_2$ follows from $\Delta_2$. Since there is an exponential number of such splits, it is important to delay the choice of a split as much as possible. A mechanism for the lazy splitting of contexts is presented based on viewing proof search as a process that takes a context, consumes part of it, and returns the rest (to be consumed elsewhere). In addition, we use collections of Kripke interpretations indexed by a commutative monoid to provide models for this logic programming language and show that logic programs admit a canonical model.}, xxx-references={JACM::AptE82, LICS::Cerrito90, LICS::HodasM91, JACM::NadathurM90} } @Article{Kozen94, refkey={C1459}, title={A Completeness Theorem for {Kleene} Algebras and the Algebra of Regular Events}, author={Dexter Kozen}, pages={366--390}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, preliminary={LICS::Kozen1991:214}, abstract={We give a finitary axiomatization of the algebra of regular events involving only equations and equational implications. Unlike Salomaa's axiomatizations, the axiomatization given here is sound for all interpretations over Kleene algebras.}, xxx-references={Immerman86, LICS::Kozen91, Leivant90, FOCS::Safra88, JACM::Salomaa66, LICS::Walukiewicz93} } @Article{Leivant94, refkey={C1455}, title={A Foundational Delineation of Poly-time}, author={Daniel Leivant}, pages={391--420}, journal=iandcomp, month={1~} # may, year=1994, volume=110, number=2, preliminary={LICS::Leivant1991:2}, abstract={We show that a function over $\{0,1\}^*$ is poly-time iff it is computed by an equational program which can be proved to be everywhere converging in constructive second order logic with set-existence (comprehension) restricted to positive quantifier-free formulas, or alternatively with set-existence for positive exixtential formulas. These set-existence principles convey an ontology of infinite sets as evolving, not completed, totalities. Our characterization results can consequently be viewed as foundational justification for identifying poly-time with feasibility.}, xxx-references={Immerman86, FOCS::Leivant83, Leivant90, LICS::Leivant91, STOC::Vardi82} } Author Index for Volume 110 -- pages 421-422 May 15, 1994 Volume 111, Number 1 Special Issue: Selections from 1992 IEEE Symposium on Logic in Computer Science (Part 1) @Article{Scedrov94, refkey={C1578}, title={Preface}, author={Andre Scedrov}, pages={iii}, journal=iandcomp, month={15~} # may, year=1994, volume=111, number=1 } @Article{AcetoBV94, refkey={C1464}, title={Turning {SOS} Rules into Equations}, author={Luca Aceto and Bard Bloom and Frits Vaandrager}, pages={1--52}, journal=iandcomp, month={15~} # may, year=1994, volume=111, number=1, preliminary={LICS::AcetoBV1992:113}, abstract={Many process algebras are defined by structural operational semantics (SOS)\@. Indeed, most such definitions are nicely structured and fit the GSOS format of [Bloom, Istrail, Meyer 88]. We give a procedure for converting any GSOS language definition to a finite complete equational axiom system (possibly with one infinitary induction principle) which precisely characterizes strong bisimulation of processes.}, xxx-references={BergstraK84, JACM::BloomIM95, GrooteV92, Hennessy81, JACM::Hennessy85, LICS::Vaandrager91} } @Article{AbramskyJ94, refkey={C1466}, title={New Foundations for the Geometry of Interaction}, author={Samson Abramsky and Radha Jagadeesan}, pages={53--119}, journal=iandcomp, month={15~} # may, year=1994, volume=111, number=1, preliminary={LICS::AbramskyJ1992:211}, abstract={The Geometry of Interaction programme is to give a semantics of computation, specifically of Cut--elimination in Linear Logic, with the following key features: \begin{itemize} \item The semantics is syntax--free and uses denotational tools, yet it captures the essential features of the computational dynamics. \item The process of Cut--elimination is modelled by the flow of information tokens around a network, rather than by graph--rewriting. \end{itemize} Girard has implemented this programme in a sequence of papers. In this paper, we present an alternative formal realisation of Girard's programme, with the following salient features. \begin{itemize} \item Our formalisation shows how the interpretation arises from the construction of a categorical model of Linear Logic; this provides the basis for a rational reconstruction which makes the structure of the interpretation much easier to understand. \item We replace the ``execution formula'' by a generalisation of Kahn's semantics for feedback in dataflow networks. Coupled with the use of the other distinctive construct of Domain theory, the lifting monad, this enables us to interpret the whole of Linear Logic, and to prove soundness in full generality. \end{itemize}}, xxx-references={JACM::GoguenTWW77, Moggi91} } @Article{Sangiorgi94, refkey={C1463}, title={The Lazy Lambda Calculus in a Concurrency Scenario}, author={Davide Sangiorgi}, pages={120--153}, journal=iandcomp, month={15~} # may, year=1994, volume=111, number=1, preliminary={LICS::Sangiorgi1992:102}, abstract={The use of $\lambda$-calculus in richer settings, possibly involving parallelism, is examined in terms of the effect on the equivalence between $\lambda$-terms. We concentrate on Abramsky's {\em lazy $\lambda$-calculus\/} (Abramsky 1989) and we follow two directions. Firstly, the $\lambda$-calculus is studied within a process calculus by examining the equivalence $\stackrel{\sim}{\leftrightarrow}$ induced by Milner's encoding into the $\pi$-calculus. We start from a characterisation of $\stackrel{\sim}{\leftrightarrow}$ presented in (Sangiorgi 1992). We derive a few simpler operational characterisations, from which we prove full abstraction w.r.t.\ Levy-Longo Trees. Secondly, we examine Abramsky's {\em applicative bisimulation\/} (in {\em op.\ cit.}) when the $\lambda$-calculus is augmented with (well-formed) operators, that is symbols equipped with reduction rules describing their behaviour. In this way, the maximal discrimination between pure $\lambda$-terms ({\em i.e.}, the finest behavioural equivalence) is obtained when all operators are used. We prove that the presence of certain non-deterministic operators is sufficient and necessary to induce it and that it coincides with the discrimination given by $\stackrel{\sim}{\leftrightarrow}$. We conclude that the introduction of non-determinism into the $\lambda$-calculus is exactly what makes applicative bisimulation appropriate for reasoning about the functional terms when concurrent features are also present in the language, or when they are embedded into a concurrent language.}, xxx-references={AbramskyO93, Boudol94, GrooteV92, MilnerPW92a, MilnerPW92b, FOCS::Ong88, LICS::Ong93} } @Article{ComonHJ94, refkey={C1467}, title={Syntacticness, Cycle-Syntacticness, and Shallow Theories}, author={Hubert Comon and Marianne Haberstrau and Jean-Pierre Jouannaud}, pages={154--191}, journal=iandcomp, month={15~} # may, year=1994, volume=111, number=1, preliminary={LICS::ComonHJ1992:255}, abstract={Solving equations in the free algebra $T(F,X)$ (i.e. {\em unification\/}) uses the two rules: $f(\vec{s}) = f(\vec{t}) \rightarrow \vec{s} = \vec{t}$ (decomposition) and $s[x] = x \rightarrow \perp$ (occur-check). These two rules are not correct in quotients of $T(F,X)$ by a finitely generated congruence $=_E$. Following C. Kirchner, we first define classes of equational theories (called {\em syntactic\/} and {\em cycle-syntactic\/} respectively) for which it is possible to derive some rules replacing the two above ones. Then, we show that these abstract classes are relevant: all {\em shallow theories}, i.e. theories which can be generated by equations in which variables occur at depth at most one, are both syntactic and cycle syntactic. Moreover, the new set of unification rules is terminating, which proves that unification is decidable and finitary in shallow theories. We give still further extensions. If the set of equivalence classes is infinite, a problem which turns out to be decidable in shallow theories, then shallow theories fulfill Colmerauer's {\em disequations is solvable iff each disequation alone is solvable}. This allows us to derive quantifier-elimination rules. It turns out that these rules do terminate for shallow theories, hence the first-order theory of the quotient algebra $T(F)/_{=_E}$ is decidable when $F$ is finite and $E$ is shallow. This extends Mal'cev results on the classes of (permutative) locally-free algebras that are completely axiomatizable.}, xxx-references={LICS::DauchetTHL87, LICS::DauchetT90, LICS::Kirchner86, LICS::KirchnerK90, STOC::Kozen77, LICS::Maher88, JACM::NelsonO80, LICS::Nipkow90, JACM::Shostak79} } June 1994 Volume 111, Number 2 Special Conference Issue: Selections from 1992 IEEE Symposium on Logic in Computer Science (Part 2) @Article{HenzingerNSY94, refkey={C1469}, title={Symbolic Model Checking for Real-Time Systems}, author={Thomas A. Henzinger and Xavier Nicollin and Joseph Sifakis and Sergio Yovine}, pages={193--244}, journal=iandcomp, month=jun, year=1994, volume=111, number=2, preliminary={LICS::HenzingerNSY1992:394}, abstract={We describe finite-state programs over real-numbered time in a guarded-command language with real-valued clocks or, equivalently, as finite automata with real-valued clocks. Model checking answers the question which states of a real-time program satisfy a branching-time specification (given in an extension of CTL with clock variables). We develop an algorithm that computes this set of states symbolically as a fixpoint of a functional on state predicates, without constructing the state space. \par For this purpose, we introduce a $\mu$-calculus on computation trees over real-numbered time. Unfortunately, many standard program properties, such as response for all nonzeno execution sequences (during which time diverges), cannot be characterized by fixpoints: we show that the expressiveness of the timed $\mu$-calculus is incomparable to the expressiveness of timed CTL\@. Fortunately, this result does not impair the symbolic verification of ``implementable'' real-time programs---those whose safety constraints are machine-closed with respect to diverging time and whose fairness constraints are restricted to finite upper bounds on clock values. All timed CTL properties of such programs are shown to be computable as finitely approximable fixpoints in a simple decidable theory.}, xxx-references={LICS::AlurCD90, FOCS::AlurH89, FOCS::AlurH92, LICS::AbadiL88, BurchCMDH92, JACM::EmersonH86, LICS::EmersonL86, LICS::Lewis90} } @Article{TalpinJ94, refkey={C1465}, title={The Type and Effect Discipline}, author={Jean-Pierre Talpin and Pierre Jouvelot}, pages={245--296}, journal=iandcomp, month=jun, year=1994, volume=111, number=2, preliminary={LICS::TalpinJ1992:162}, abstract={The {\em type and effect discipline\/} is a new framework for reconstructing the principal type and the minimal effect of expressions in implicitly typed polymorphic functional languages that support imperative constructs. The type and effect discipline outperforms other polymorphic type systems. Just as types abstract collections of concrete values, {\em effects\/} denote imperative operations on regions. {\em Regions\/} abstract sets of possibly aliased memory locations. \par Effects are used to control type generalization in the presence of imperative constructs while regions delimit observable side-effects. The observable effects of an expression range over the regions that are free in its type environment and its type; effects related to local data structures can be discarded during type reconstruction. The type of an expression can be generalized with respect to the type variables that are not free in the type environment or in the observable effect. \par Introducing the type and effect discipline, we define both a dynamic and a static semantics for an ML-like language and prove that they are consistently related. We present a reconstruction algorithm that computes the principal type and the minimal observable effect of expressions. We prove its correctness with respect to the static semantics.}, xxx-references={JACM::Robinson65, LICS::TalpinJ92} } @Article{CartwrightCF94, refkey={C1470}, title={Fully Abstract Semantics for Observably Sequential Languages}, author={Robert Cartwright and Pierre-Louis Curien and Matthias Felleisen}, pages={297--401}, journal=iandcomp, month=jun, year=1994, volume=111, number=2, preliminary={LICS::Curien1992:432}, abstract={One of the major challenges in denotational semantics is the construction of a fully abstract semantics for a higher-order {\em sequential} programming language. For the past fifteen years, research on this problem has focused on developing a semantics for PCF, an idealized functional programming language based on the typed $\lambda$-calculus. Unlike most practical languages, PCF has no facilities for {\em observing\/} and {\em exploiting\/} the evaluation order of arguments to procedures. Since we believe that these facilities play a crucial role in sequential computation, this paper focuses on a sequential extension of PCF, called SPCF, that includes two classes of control operators: a possibly empty set of error generators and a collection of {\em catch\/} and {\em throw\/} constructs. For each set of error generators, the paper presents a fully abstract semantics for SPCF. If the set of error generators is empty, the semantics interprets all procedures---including catch and throw---as Berry-Curien {\em sequential algorithms}. If the language contains error generators, procedures denote {\em manifestly sequential\/} functions. The manifestly sequential functions form a Scott domain that is isomorphic to a domain of decision trees, which is the natural extension of the Berry-Curien domain of sequential algorithms in the presence of errors.}, xxx-references={LICS::Curien92} } Author Index for Volume 111 -- page 402 July 1994 Volume 112, Number 1 @Article{AbadiH94, refkey={C1041}, title={Decidability and Expressiveness for First-Order Logics of Probability}, author={Mart{\'\i}n Abadi and Joseph Y. Halpern}, pages={1--36}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={We consider decidability and expressiveness issues for two first-order logics of probability. In one, the probability is on possible worlds, while in the other, it is on the domain. It turns out that in both cases it takes very little to make reasoning about probability highly undecidable. We show that when the probability is on the domain, if the language contains only unary predicates then the validity problem is decidable. However, if the language contains even one binary predicate, the validity problem is $\Pi^2_1$ complete, as hard as elementary analysis with free predicate and function symbols. With equality in the language, even with no other symbol, the validity problem is at least as hard as that for elementary analysis, $\Pi_\infty^1$ hard. Thus, the logic cannot be axiomatized in either case. When we put the probability on the set of possible worlds, the validity problem is $\Pi^2_1$ complete with as little as one unary predicate in the language, even without equality. With equality, we get $\Pi_\infty^1$ hardness with only a constant symbol. We then turn our attention to an analysis of what causes this overwhelming complexity. For example, we show that if we require rational probabilities then we drop from $\Pi^2_1$ to $\Pi_1^1$. In many contexts it suffices to restrict attention to domains of bounded size; fortunately, the logics are decidable in this case. Finally, we show that, although the two logics capture quite different intuitions about probability, there is a precise sense in which they are equi-expressive.}, xxx-references={FaginHM90} } @Article{LevcopoulosP94, refkey={C1074}, title={Sorting Shuffled Monotone Sequences}, author={Christos Levcopoulos and Ola Petersson}, pages={37--50}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={We present a new sorting algorithm that adapts to existing order within the input sequence. Let $k$ be the smallest integer such that a sequence~$X$ of length~$n$ can be reduced to the empty sequence by the removal of $k$~monotone, increasing or decreasing, subsequences. The algorithm, Slabsort, sorts~$X$ in $O(n\log k)$ time, without knowing~$k$ beforehand, which is optimal in a comparison-based model.}, xxx-references={Estivill-CastroW89} } @Article{Grolmusz94, refkey={C1258}, title={The {BNS} Lower Bound for Multi-Party Protocols in Nearly Optimal}, author={Vince Grolmusz}, pages={51--54}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={We present a {\em multi--party protocol\/} which computes the {\em Generalized Inner Product\/} (GIP) function, introduced by {\em Babai, Nisan and Szegedy\/} (1989, in Proceedings, 21st ACM STOC, pp.~1-11). Our protocol shows that the lower bound for the multi--party communication complexity of the GIP function, given by {\em Babai et al}, cannot be improved significantly.}, references={JCSS::BabaiNS1992:204, STOC::BabaiNS1989, STOC::ChandraFL1983:94, FOCS::HastadG1990, CC::HastadG1991:113, FOCS::LovaszS1988:81, MISC::Lovasz1989:235, STOC::Yao1979:209} } @Article{Hennessy94, refkey={C1456}, title={A Fully Abstract Denotational Model for Higher-Order Processes}, author={M. Hennessy}, pages={55--95}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, xxx-references={AbramskyO93, Boudol94, HennessyI93, JACM::HennessyM85, MilnerPW92a, MilnerPW92b} } @Article{Parberry94, refkey={C1213}, title={A Guide for New Referees in Theoretical Computer Science}, author={Ian Parberry}, pages={96--116}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={In the mathematical sciences the paradigm for publication is to describe the mathematical proofs of propositions in sufficient detail to allow duplication by interested readers. Quality control is achieved by a system of peer review commonly referred to as {\em refereeing}. This guide is an attempt to distill the experience of the theoretical computer science community on the subject of refereeing into a convenient form which can be easily distributed to students and other inexperienced referees. Although aimed primarily at theoretical computer scientists, it contains advice which may be relevant to other mathematical sciences. It may also be of some use to new authors who are unfamiliar with the peer review process.}, xxx-references={STOC::Cook71, JACM::HopcroftPV77, FOCS::JohnsonPY85} } @Article{YanP94, refkey={C1156}, title={Exponential Size Lower Bounds for Some Depth Three Circuits}, author={P. Y. Yan and Ian Parberry}, pages={117--130}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={Exponential size lower bounds are obtained for some depth three circuits computing conjunction using one layer each of gates which compute Boolean functions of low total degree when expressed as polynomials, parity-modulo-$2$ gates, and parity-modulo-$q$ gates, where $q$ is prime. One of these results implies a special case of the {\em constant degree hypothesis\/} of Barrington {\em et al}. The lower bounds are obtained from an algebraic characterization of the functions computed by the circuits: it is shown that certain integer multiples of these functions can be expressed as the sum of a lattice element and a function of small value. It is conjectured that this characterization can be used to resolve the constant degree hypothesis.}, xxx-references={FOCS::HajnalMPST87, STOC::Hastad86, FOCS::HastadG90, STOC::Sipser83, STOC::Smolensky87, STOC::Yao89, FOCS::Yao85} } @Article{Pierce94, refkey={C1330}, title={Bounded Quantification is Undecidable}, author={Benjamin C. Pierce}, pages={131--165}, journal=iandcomp, month=jul, year=1994, volume=112, number=1, abstract={$F_\leq$ is a typed $\lambda$-calculus with subtyping and bounded second-order polymorphism. First introduced by Cardelli and Wegner, it has been widely studied as a core calculus for type systems with subtyping. \par Curien and Ghelli proved the partial correctness of a recursive procedure for computing minimal types of $F_\leq$ terms and showed that the termination of this procedure is equivalent to the termination of its major component, a procedure for checking the subtype relation between $F_\leq$ types. This procedure was thought to terminate on all inputs, but the discovery of a subtle bug in a purported proof of this claim recently reopened the question of the decidability of subtyping, and hence of typechecking. \par This question is settled here in the negative, using a reduction from the halting problem for two-counter Turing machines to show that the subtype relation of $F_\leq$ is undecidable.}, xxx-references={Breazu-TannenCGS91, BruceL90, Cardelli88, Mitchell88} } August 1, 1994 Volume 112, Number 2 @Article{ComonD94, refkey={C1204}, title={Equational Formulae with Membership Constraints}, author={Hubert Comon and Catherine Delor}, pages={167--216}, journal=iandcomp, month={1~} # aug, year=1994, volume=112, number=2, abstract={We propose a set of transformation rules for first order formulae whose atoms are either equations between terms or ``membership constraints'' $t\in\zeta$. $\zeta$ can be interpreted as a regular tree language ($\zeta$ is called a {\em sort\/} in the algebraic specification community) or as a tree language in any class of languages which satisfies some adequate closure and decidability properties. This set of rules is proved to be correct, terminating and complete. This provides a quantifier elimination procedure: for every regular tree language $\cal L$, the first order theory of some structure defining $\cal L$ is decidable. This extends former results of (Mal'cev 62, Maher 88, Comon and Lescanne 89). We also show how to apply our results to automatic inductive proofs in equational theories.}, xxx-references={LICS::GoguenM87, LICS::JouannaudK86, LICS::Maher88, LICS::Mosses89a, Plaisted85} } @Article{AllenderH94, refkey={C1184}, title={Depth Reduction for Circuits of Unbounded Fan-In}, author={Eric Allender and Ulrich Hertrampf}, pages={217--238}, journal=iandcomp, month={1~} # aug, year=1994, volume=112, number=2, abstract={We prove that constant depth circuits of size $2^{\mathop{\rm polylog}(n)}$ over the basis AND, OR, PARITY are no more powerful than circuits of this size with depth four. Similar techniques are used to obtain several other depth reduction theorems; in particular, we show every set in AC$^O$ can be recognized by a family of depth-three threshold circuits of size $2^{\mathop{\rm polylog}(n)}$. The size bound $2^{\mathop{\rm polylog}(n)}$ is optimal when considering depth reduction over AND, OR, and PARITY. Most of our results hold both for the uniform and the nonuniform case.}, xxx-references={FOCS::Adleman78, STOC::AjtaiB84, FOCS::Allender89, JACM::Allender89, FOCS::BeigelT91, FOCS::BruckS90, DenenbergGS86, FOCS::HajnalMPST87, FOCS::HastadG90, KannanVVY93, FOCS::NisanW88, STOC::Sipser83, STOC::Smolensky87, JACM::Toran91, FOCS::Yao85, STOC::Yao89, FOCS::Yao90} } @Article{DimopoulosM94, refkey={C1242}, title={A Graph-Theoretic Approach to Default Logic}, author={Yannis Dimopoulos and Vangelis Magirou}, pages={239--256}, journal=iandcomp, month={1~} # aug, year=1994, volume=112, number=2, abstract={A network representation of propositional seminormal disjunction-free default theories is presented, leading to a graph-theoretic approach to their analysis. The problem of finding an extension is proved to be equivalent to that of determining a kernel for a corresponding graph, allowing stronger complexity results as well as new conditions for the existence of extensions.}, xxx-references={JACM::MarekT91} } @Article{PaturiS94, refkey={C1225}, title={Approximating Threshold Circuits by Rational Functions}, author={Ramamohan Paturi and Michael E. Saks}, pages={257--272}, journal=iandcomp, month={1~} # aug, year=1994, volume=112, number=2, abstract={Motivated by the problem of understanding the limitations of threshold networks for representing boolean functions, we consider size--depth trade--offs for threshold circuits that compute the parity function. Using a fundamental result in the theory of rational approximation, we show how to approximate small threshold circuits by rational functions of low degree. We apply this result to establish an almost optimal lower bound of $\Omega(n^2 /\log^2 n)$ on the number of edges of any depth--2 threshold circuit with polynomially bounded weights that computes the parity function. We also prove that any depth--3 threshold with polynomially bounded weights requires $\Omega(n^{1.2}/\ln^{5/3} n)$ edges to compute parity. On the other hand, we give a construction of a depth $d$ threshold circuit that computes parity with $n^{1+1/\Theta(\phi^d)}$ edges where $\phi = (1 + \sqrt{5})/2$ is the golden ratio. We conjecture that there are no linear size bounded depth threshold circuits for computing parity.}, references={APAL::M1983, IEEETIT::AlonBCO1988, STOC::AspnesBFR1991:402, TR::BeameBL1990, SICOMP::BeameCH1986, STOC::BeigelRS1991:1, HTCS::BoppanaS1990, SIDSMA::Bruck1990, FOCS::BruckS1990:632, SICOMP::ChandraSV1984:423, MST::FurstSS1984, FOCS::HajnalMPST1987:99, TR::Hinton1987, BOOK::MinskyP1969, BOOK::Muroga1971, MICMJ::Newman1964, JCSS::ParberryS1988, MATHZA::Razborov1986, SCTC::Reif1987, IEEETC::SiuRK1991, STOC::Smolensky1987:77, THESISP::Szegedy1989, TR::Wegener1990, STOC::Yao1989:186, FOCS::Yao1990:619} } @Article{HenzingerMP94, refkey={C1487}, title={Temporal Proof Methodologies for Timed Transition Systems}, author={Thomas A. Henzinger and Zohar Manna and Amir Pnueli}, pages={273--337}, journal=iandcomp, month={1~} # aug, year=1994, volume=112, number=2, abstract={We extend the specification language of temporal logic, the corresponding verification framework, and the underlying computational model to deal with real-time properties of reactive systems. The abstract notion of timed transition systems generalizes traditional transition systems conservatively: qualitative fairness requirements are replaced (and superseded) by quantitative lower-bound and upper-bound timing constraints on transitions. This framework can model real-time systems that communicate either through shared variables or by message passing and real-time issues such as timeouts, process priorities (interrupts), and process scheduling. \par We exhibit two styles for the specification of real-time systems. While the first approach uses time-bounded versions of the temporal operators, the second approach allows explicit references to time through a special clock variable. Corresponding to the two styles of specification, we present and compare two different proof methodologies for the verification of timing requirements that are expressed in these styles. For the {\em bounded-operator\/} style, we provide a set of proof rules for establishing bounded-invariance and bounded-response properties of timed transition systems. This approach generalizes the standard temporal proof rules for verifying invariance and response properties conservatively. For the {\em explicit-clock\/} style, we exploit the observation that every time-bounded property is a safety property and use the standard temporal proof rules for establishing safety properties.}, xxx-references={LICS::AlurH90, LICS::AbadiL88, LICS::HarelLP90, KoymansSRGA88, FOCS::Pnueli77} } Author Index for Volume 112 -- page 338 August 15, 1994 Volume 113, Number 1 @Article{Beaudry94, refkey={C1146}, title={Membership Testing in Threshold One Transformation Monoids}, author={M. Beaudry}, pages={1--25}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, xxx-references={STOC::BabaiLS87, Beaudry88, JACM::BeaudryMT92, STOC::Buss87, Cook85, FOCS::FurstHL80, FOCS::Kozen77, FOCS::Luks86, STOC::Smolensky87, Stern85} } @Article{Wanke94, refkey={C1232}, title={On the Decidability of Certain Integer Subgraph Problems on Context-Free Graph Languages}, author={Egon Wanke}, pages={26--49}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, abstract={We show the decidability of certain integer subgraph problems (ISPs) on context-free sets of graphs $L(\Gamma)$ defined by hyperedge replacement systems (HRSs) $\Gamma$. An ISP $\Pi$ consists of a property $s_\Pi$ and a mapping $f_\Pi$. If $J$ is a subgraph of some graph $G$ then $s_\Pi(G,J)$ is true or false and $f_\Pi(G,J)$ is an integer. We define the notion of a \emph{finite} and \emph{additive} ISP and show the following result: Let $\Pi_1,\ldots,\Pi_n$ be $n$ finite and additive ISPs and $L(\Gamma)$ be a set of graphs defined by a HRS $\Gamma$. Then the set of all $n$-tuples $(f_{\Pi_1}(G,J_1),\ldots,f_{\Pi_n}(G,J_n))$ for all graphs $G$ from $L(\Gamma)$ and all subgraphs $J_1,\ldots,J_n$ of $G$ for which $s_{\Pi_i}(G,J_i)$ holds true for $1 \leq i \leq n$, is a semilinear set of integers. Using integer linear programming methods, we can compute a lot of optimization problems on context-free sets of graphs.}, xxx-references={GGACS::ClausER79, TR::CourcelleM90, TCS::Courcelle87, IC::Courcelle90, GGACS::EhrigNR83, GGACS::EhrigNRR87, BOOK::GareyJ79, GGACS::HabelK87, TAPSOFT::HabelKV89, ACTAI::HabelKV89, BOOK::HopcroftU79, BOOK::Lengauer90, JACM::LengauerW93, BOOK::MeadC80, BOOK::NemhauserW89, JACM::Parikh66, BOOK::PapadimitriouS82, JALGO::RobertsonS86, IC::RozenbergW86, BOOK::Salomaa73, THESIS::Wanke89, IC::Wanke91, IPL::WankeW89} } @Article{EllisST94, refkey={C1161}, title={The Vertex Separation and Search Number of a Graph}, author={J. A. Ellis and I. H. Sudborough and J. S. Turner}, pages={50--79}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, abstract={We relate two concepts in graph theory and algorithmic complexity, namely the \emph{search number} and the \emph{vertex separation} of a graph. Let $s(G)$ denote the search number and $vs(G)$ denote the vertex separation of a connected, undirected graph $G$. We show that $vs(G) \le s(G) \le vs(G) + 2$ and we give a simple transformation from $G$ to $G'$ such that $vs(G') = s(G)$. We characterize those trees having a given vertex separation and describe the smallest such trees. We also note that there exist trees for which the difference between search number and vertex separation is indeed 2. We give algorithms that, for any tree $T$, compute $vs(T)$ in linear time and compute an optimal layout with respect to vertex separation in time $O(n \log n)$. Vertex separation has previously been related to \emph{progressive black/white pebble demand} and has been shown to be identical to a variant of search number, \emph{node search number}, and to \emph{path width}, which has been related directly to \emph{gate matrix layout cost}. All these properties are known to be computationally intractable. For fixed $k$, an $O(n \log^2 n)$ algorithm is known which decides whether a graph has path width at most $k$.}, xxx-references={JACM::FellowsL88, STOC::FellowsL89, JACM::LaPaugh93, FOCS::Leiserson80, JACM::MegiddoHGJP88, JACM::Yannakakis85} } @Article{SchieberS94, refkey={C961}, title={Calling Names on Nameless Networks}, author={Baruch Schieber and Marc Snir}, pages={80--101}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, abstract={We consider the problem of constructing a rooted spanning tree in an anonymous (connected) network. In case no upper bound on the network size is known, we give the following algorithms, all of which have error probability $\epsilon$: (1) A message terminating algorithm that runs in $O(n)$ time and $O(m\log(n^2/m))$ messages, each of size $O(\log(n/\epsilon))$, where $n$ and $m$ are the number of nodes and links in the network. (2) A message terminating algorithm with expected running time $O(n\log\log(n/\epsilon))$ and expected message complexity $O(n\log n + m \log\log(n/\epsilon))$, each of size $O(\log(n/\epsilon))$. For any fixed $\epsilon$, this algorithm can be modified to run in $O(n f(n))$ expected time and $O(n\log n + m f(n))$ expected message complexity, where $f(n)$ is any slowly-growing function. However, this requires the use of longer messages. \par In case an upper bound on the network size is known, we give a processor terminating algorithm with error probability $\epsilon$ that runs in $O(n)$ time, and $O(n \log n +m)$ messages. Finally, in case the network size is known within a factor of two, we give an algorithm that processor terminates and always succeeds, in expected $O(n)$ time and $O(n\log n + m)$ messages.}, xxx-references={STOC::Angluin80, JACM::AttiyaSW88, JACM::Awerbuch85, STOC::Awerbuch87, FOCS::ItaiR81, ItaiR90}, full-xxx-references={PODC::AbrahamsonAHK86, STOC::Angluin80, JACM::AttiyaSW88, JACM::Awerbuch85, STOC::Awerbuch87, TOPLAS::GallagerHS83, FOCS::ItaiR81, ItaiR90, WDAG::MatiasA89, IEEEIT::Segall83, PODC::YamashitaK88} } @Article{GerberL94, refkey={C1168}, title={A Resource-Based Prioritized Bisimulation for Real-Time Systems}, author={Richard Gerber and Insup Lee}, pages={102--142}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, xxx-references={LICS::CamilleriW91, CleavelandH90, KoymansSRGA88, Milner89} } @Article{ContejeanD94, refkey={C1404}, title={An Efficient Incremental Algorithm for Solving Systems of Linear {Diophantine} Equations}, author={Evelyne Contejean and Herv{\'e} Devie}, pages={143--172}, journal=iandcomp, month={15~} # aug, year=1994, volume=113, number=1, abstract={In this paper, we describe an algorithm for solving systems of linear Diophantine equations based on a generalization of an algorithm for solving one equation due to Fortenbacher (Clausen and Fortenbacher, 1989). It can solve a system as a whole, or be used incrementally when the system is a sequential accumulation of several subsystems. The proof of termination of the algorithm is difficult, whereas the proofs of completeness and correctness are straightforward generalizations of Fortenbacher's proof.}, xxx-references={LICS::BoudetCD90} } September 1994 Volume 113, Number 2 @Article{TaubenfeldKM94, title={Impossibility Results in the Presence of Multiple Faulty Processes}, author={Gadi Taubenfeld and Shmuel Katz and Shlomo Moran}, pages={173--198}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, xxx-references={JACM::AttiyaBDPR90, FOCS::AttiyaBDKPR87, JACM::DolevDS87, JACM::FischerLP85, JACM::HalpernM90} } @Article{ChinM94, title={Virtual Shared Memory: Algorithms and Complexity}, author={Andrew Chin and W. F. McColl}, pages={199--219}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, abstract={We consider the Block PRAM model of Aggarwal, Chandra and Snir (1989). For a Block PRAM model with $n/\log n$ processors and communication latency $l=O(\log n)$, we show that prefix sums can be performed in time $O(l\log n/\log l)$, but list ranking requires time $\Omega (l\log n)$; these bounds are tight. These results justify an intuitive observation of Gazit, Miller and Teng (1987) that algorithm designers should, when possible, replace the list ranking procedure with the prefix sums procedure. We demonstrate the value of this technique in choosing between two optimal PRAM algorithms for finding the connected components of dense graphs. We also give theoretical improvements for integer sorting and many other algorithms based on prefix sums, and suggest a relationship between the issue of graph density for the connected components problem and alternative approaches to integer sorting.}, xxx-references={ColeV86, FOCS::ColeV86, STOC::Hirschberg76, JACM::LadnerF80, STOC::PapadimitriouY88, FOCS::Reif85} } @Article{Ogielski94, title={Minimal Samples of Positive Examples Identifying {$k$}-{CNF} {Boolean} Functions}, author={Andrew T. Ogielski}, pages={220--229}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, xxx-references={JACM::PittV88} } @Article{LongW94, title={Composite Geometric Concepts and Polynomial Predictability}, author={Philip M. Long and Manfred K. Warmuth}, pages={230--252}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, xxx-references={JACM::BlumerEHW89, FOCS::GoldreichKL88, HausslerKLW91, FOCS::HausslerLW88, JACM::PittV88} } @Article{WandW94, refkey={C1152}, title={Conditional Lambda-Theories and the Verification of Static Properties of Programs}, author={Mitchell Wand and Zheng-Yu Wang}, pages={253--277}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, abstract={We present a proof that a simple compiler correctly uses the static properties in its symbol table. We do this by regarding the target code produced by the compiler as a syntactic variant of a $\lambda$-term. In general, this $\lambda$-term $C$ may not be equal to the semantics $S$ of the source program: they need be equal only when information in the symbol table is valid. We formulate this relation as a {\em conditional $\lambda$-judgement\/} $\bar\Gamma \subset S = C$, where $\bar\Gamma$ is a formula that represents the invariants implicit in symbol table~$\Gamma$. We present rules of inference for conditional $\lambda$-judgements and prove their soundness. We then use these rules to prove the correctness of a simple compiler that relies on a symbol table. The form of the proof suggests that such proofs may be largely mechanizable.}, references={BOOK::AbramskyH1987, POPL::AppelJ1989, JSYML::Church1940, BOOK::FriedmanWH1992, POPL::HalpernMT1984, POPL::KelseyH1989, IC::Meyer1982:87, POPL::MeyerS1988, IC::MontenyohlW1989:151, TCS::Plotkin1975:125, MISC::Reynolds1981, TOPLAS::Schmidt1985, THESIS::Suzuki1976, POPL::Wand1982, TOPLAS::Wand1982, IC::Wand1983:148, IPL::Wand1990, MFPS::Wand1991, TR::WandW1990} } @Article{HarelR94, refkey={C1207}, title={Deciding Emptiness for Stack Automata on Infinite Trees}, author={David Harel and Danny Raz}, pages={278--299}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, abstract={We show that the emptiness problem for B\"uchi stack automata on infinite trees is decidable in elementary time. We first establish the decidability of the emptiness problem for {\em pushdown\/} automata on infinite trees. This is done using a pumping-like argument applied to computation trees. We then show how to reduce the emptiness problem for stack automata to the emptiness problem for pushdown automata. Elsewhere, we have used the result to establish the decidability of several versions of nonregular dynamic logic.}, xxx-references={FOCS::HossleyR72, FOCS::HarelR90} } @Article{Jerrum94, refkey={C1241}, title={Simple Translation-Invariant Concepts Are Hard to Learn}, author={Mark Jerrum}, pages={300--311}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, abstract={The concept class TCM of ``translation-closed monomials'' was proposed by Maragos and Valiant as a natural starting point for the investigation of the computational complexity of learning translation-invariant concepts. Concepts in TCM are (satisfying assignments to) DNF formulas such as \[ (x_0\wedge x_1\wedge x_3)\vee(x_1\wedge x_2\wedge x_4)\vee\cdots\vee (x_4\wedge x_0\wedge x_2),\] (over the variables $x_0,x_1,\ldots,x_4$) which are generated from a single monomial (conjunction of variables) by cyclically permuting indices and forming a disjunction. Note that concepts in TCM are invariant under cyclic permutation of the variable set. \par This note investigates the computational complexity of learning TCM concepts within the Valiant (PAC) model. Despite their obvious simplicity, TCM concepts are apparently difficult to learn. Indeed: \begin{enumerate} \item the concept class TCM is not polynomially learnable unless ${\rm RP}={\rm NP}$; \item TCM is polynomially predictable if and only if the concept class of DNF formulas is polynomially predictable; \item TCM is not polynomially predictable from positive examples alone. \end{enumerate} The second of these results relates the computational complexity of predicting TCM concepts to a well known open problem in computational learning theory.}, references={BOOK::BalcazarDG1988, JACM::BlumerEHW1989, COLT::HausslerKLW1988, HausslerKLW1991, STOC::KearnsLPV1987, STOC::KearnsV1989, JACM::PittV1988, JCSS::PittW1990, CACM::Valiant1984, MISC::Valiant1991} } @Article{AfekM94, refkey={C1254}, title={Elections in Anonymous Networks}, author={Yehuda Afek and Yossi Matias}, pages={312--330}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, xxx-references={FOCS::AfekAPS87, STOC::Angluin80, JACM::AttiyaSW88, JACM::Awerbuch85, STOC::Awerbuch87, STOC::ColeV86, ItaiR90, SchieberS94} } @Article{Shallit94, refkey={C1380}, title={Numeration Systems, Linear Recurrences, and Regular Sets}, author={Jeffrey Shallit}, pages={331--347}, journal=iandcomp, month=sep, year=1994, volume=113, number=2, abstract={A numeration system based on a strictly increasing sequence of positive integers $u_0 = 1, u_1, u_2, \ldots$ expresses a non-negative integer $n$ as a sum $n = \sum_{j=0}^i a_j u_j$. In this case we say the string $a_i a_{i-1} \cdots a_1 a_0$ is a {\em representation\/} for $n$. If $\gcd(u_0, u_1, \ldots) = g$, then every sufficiently large multiple of $g$ has some representation. \par If the lexicographic ordering on the representations is the same as the usual ordering of the integers, we say the numeration system is {\em order-preserving}. In particular, if $u_0 =1$, then the {\em greedy representation}, obtained via the greedy algorithm, is order-preserving. We prove that, subject to some technical assumptions, if the set of all representations in an order-preserving numeration system is regular, then the sequence $u = (u_j)_{j \geq 0}$ satisfies a linear recurrence. The converse, however, is not true. \par The proof uses two lemmas about regular sets that may be of independent interest. The first shows that if $L$ is regular, then the set of lexicographically greatest strings of every length in $L$ is also regular. The second shows that the number of strings of length $n$ in a regular language $L$ is bounded by a constant (independent of $n$) iff $L$ is the finite union of sets of the form $x y^* z$.}, xxx-references={CulikS83, Fraenkel89, Frougny88} } Author Index for Volume 113 -- page 348 October 1994 Volume 114, Number 1 @Article{Breazu-TannenG94, refkey={C1082}, title={Polymorphic Rewriting Conserves Algebraic Confluence}, author={Val Breazu-Tannen and Jean Gallier}, pages={1--29}, journal=iandcomp, month=oct, year=1994, volume=114, number=1, xxx-references={BruceMM90, LICS::Breazu-Tannen88a, CoquandH88, Dougherty92, JACM::FortuneLO83, FOCS::Statman81, JACM::Toyama87} } @Article{BohmI94, refkey={C1171}, title={The Ant-Lion Paradigm for Strong Normalization}, author={Corrado B{\"o}hm and Benedetto Intrigila}, pages={30--49}, journal=iandcomp, month=oct, year=1994, volume=114, number=1 } @Article{Esparza94, refkey={C1265}, title={Reduction and Synthesis of Live and Bounded Free Choice {Petri} Nets}, author={Javier Esparza}, pages={50--87}, journal=iandcomp, month=oct, year=1994, volume=114, number=1 } @Article{RivestS94, refkey={C1163}, title={A Formal Model of Hierarchical Concept Learning}, author={Ronald L. Rivest and Robert Sloan}, pages={88--114}, journal=iandcomp, month=oct, year=1994, volume=114, number=1, xxx-references={JACM::GoldreichGM86, STOC::KearnsL88, STOC::KearnsLPV87, STOC::KearnsV89, Kugel77, JACM::PittV88, JACM::PittW93, RivestS93} } @Article{SorensonP94, refkey={C1257}, title={Two Fast Parallel Prime Number Sieves}, author={Jonathan Sorenson and Ian Parberry}, pages={115--130}, journal=iandcomp, month=oct, year=1994, volume=114, number=1, abstract={A {\em prime number sieve\/} is an algorithm that finds all prime numbers up to a given bound $n$. Two parallel prime number sieves for an algebraic EREW PRAM model of computation are presented and analyzed. The first sieve runs in $O(\log n)$ time using $O(n / (\log n\log\log n))$ processors, and the second sieve runs in $O(\sqrt{n})$ time using $O(\sqrt{n})$ processors. The first sieve is optimal in the sense that it performs work $O(n / \log\log n)$, which is within a constant factor of the number of arithmetic operations used by the fastest known sequential prime number sieves. However, when both sieves are analyzed on the Block PRAM model as defined by Aggarwal, Chandra, and Snir, it is found that the second sieve is more work efficient when communication latency is significant.}, xxx-references={ColeV89, JACM::Goldschlager82} } @Article{NicollinS94, refkey={C1253}, title={The Algebra of Timed Processes, {\bf ATP}: Theory and Application}, author={Xavier Nicollin and Joseph Sifakis}, pages={131--178}, journal=iandcomp, month=oct, year=1994, volume=114, number=1, abstract={The algebra of timed processes, {\bf ATP}, uses a notion of discrete global time and suggests a conceptual framework for introducing time by extending untimed languages. The action vocabulary of {\bf ATP} contains a special element representing the progress of time. The algebra has, apart from standard operators of process algebras such as prefixing by an action, alternative choice, and parallel composition, a primitive {\em unit-delay\/} operator. For two arguments, processes $P$ and $Q$, this operator gives a process which behaves as $P$ before the execution of a time event and behaves as $Q$ afterwards. It is shown that several $d$-unit delay constructs such as {\em timeouts\/} and {\em watchdogs\/} can be expressed in terms of the unit-delay operator and standard process algebra operators. A sound and complete axiomatization for bisimulation semantics is studied and two examples illustrating the adequacy of the language for the description of timed systems are given. Finally, we provide a comparison with existing timed process algebras.}, references={TCS::AustryB1984, LICS::AlurCD1990:414, TR::BaetenB1990, LNCS::BerryC1984:389, TR::BadouelD1990, POPL::BloomIM1988, TR::BergstraK1984, MISC::BergstraK1986:61, POPL::CaspiPHP1987, TR::DaviesS1989, TR::Groote1989, TR::Groote1990, TR::GrooteV1988, SCP::Harel1987:231, CACM::Hoare1978:666, IC::HennessyR1995:221, ICALP::LehmannPS1981:264, BOOK::Milner1980, TCS::Milner1983, JCSS::Milner1984, CONCUR::MollerT1990:401, IFIP::NicollinRSV1990, CAV::NicollinS1991, REX::NicollinSY1991, TR::Plotkin1981, TCS::ReedR1988:249, MISC::RichierSV1987, CONCUR::Yi1990:502, ICALP::Yi1991} } November 1, 1994 Volume 114, Number 2 @Article{FulkJ94, refkey={C1123}, title={Approximate Inference and Scientific Method}, author={Mark Fulk and Sanjay Jain}, pages={179--191}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, abstract={A new identification criterion, motivated by notions of successively improving approximations in the philosophy of science, is defined. It is shown that the class of recursive functions is identifiable under this criterion. This result is extended to permit somewhat more realistic types of data than usual. This criterion is then modified to consider restrictions on the quality of approximations, and the new criteria are compared to existing criteria.}, references={ACMCS::AngluinS1983, MISC::Barzdin1974, IC::BlumB1975, JACM::Blum1967, MST::Case1974, TCS::CaseS1983, THESIS::Chen1981, THESIS::Fulk1985, IC::Gold1967, INFOS::KletteW1980, BOOK::OshersonSW1986, BOOK::Peirce1958, JSYML::Rogers1958, BOOK::Rogers1967, IC::Royer1986, MISC::SmithV1986, THESIS::Wiehagen1978} } @Article{ShemeshF94, refkey={C881}, title={Finite-State Unification Automata and Relational Languages}, author={Yael Shemesh and Nissim Francez}, pages={192--213}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, xxx-references={FOCS::KaminskiF90, FOCS::UllmanG86} } @Article{KranakisKB94, refkey={C1114}, title={Computing {Boolean} Functions on Anonymous Networks}, author={Evangelos Kranakis and Danny Krizanc and Jacob van den Berg}, pages={214--236}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, abstract={We study the bit-complexity of computing Boolean functions on anonymous networks. Let $N$ be the number of nodes, $\delta$ the diameter and $d$ the maximal node degree of the network. For arbitrary, anonymous networks we give a general algorithm of polynomial bit complexity $O(N^3 \cdot \delta \cdot d^2 \cdot \log N)$ for computing any Boolean function which is computable on the network. This improves upon the previous best known algorithm which was of exponential bit complexity $O(d^{N^2})$. For symmetric functions on arbitrary networks we give an algorithm with bit complexity $O(N^2 \cdot \delta \cdot d^2 \cdot \log^2 N)$. This same algorithm is shown to have even lower bit complexity for a number of specific networks, for example tori, hypercubes and random regular graphs. We also consider the class of distance regular unlabeled networks and show that on such networks symmetric functions can be computed efficiently in $O(N\cdot \delta \cdot d \cdot \log N)$ bits.}, references={WDAG::AbrahamsonAHK1987:324, STOC::Angluin1980:82, JALGO::AttiyaS1991:204, JACM::AttiyaSW1988:845, PODC::YamashitaK1988:117, STACS::BeameB1989:294, BOOK::Biggs1974, JATP::BroderK1989:101, BOOK::BrouwerCN1989, BOOK::Cameron1983:89, FOCS::DurisG1987:326, STOC::FriedmanKS1989:587, BOOK::Gantmacher1959, TR::KranakisK1990, SPDP::KranakisK1991, LINAA::LandauO1981:5, WDAG::MatiasA1989:183, PODC::MoranW1986:131, TR::Norris1990, JACM::PachlKR1984:905, PODC::SchieberS1989:319, BOOK::Seneta1981, WDAG::Tel1987:13, PODC::YamashitaK1987:117} } @Article{Hashiguchi94, refkey={C1099}, title={The Infinite 2-Star Height Hierarchy of Extended Regular Languages of Star Degree at Most Two}, author={Kosaburo Hashiguchi}, pages={237--246}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, xxx-references={DejeanS66, Hashiguchi88, Yntema67, Yntema71} } @Article{BoudolC94, refkey={C1271}, title={Flow Models of Distributed Computations: Three Equivalent Semantics for {CCS}}, author={G{\'e}rard Boudol and Ilaria Castellani}, pages={247--314}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, abstract={We introduce three notions of computation for processes described as CCS terms. The first one uses an adaptation of the equivalence by permutations of Berry and L\'evy. In this setting, a computation is an equivalence class of sequences of transitions, up to the permutation of independent steps. The second notion of computation is given by means of an interpretation of CCS into a new class of event structures, the flow event structures. This can be seen as a reformulation of Winskel's semantics for CCS by means of stable event structures. Here a computation is a configuration of an event structure. Finally, our third notion of computation is determined by an interpretation of CCS terms as Petri nets, and more precisely as flow nets. Here a computation is a set of events that are firable in sequence in the net. We then show that these three computational interpretations of CCS coincide, in the sense that for a given term, the three domains of computations are isomorphic. To this end we use an intermediary transition system for CCS, where the past is recorded; this appears to be a system of ``trace computations'', which provides another means to define the same abstract domain of computations.}, xxx-references={JACM::BerryL79, JACM::BrookesHR84, JACM::CastellaniH89, LICS::DeganoNM88, LICS::DeganoMM89} } @Article{EhrenfeuchtHR94, refkey={C1381}, title={Combinatorial Properties of Dependence Graphs}, author={A. Ehrenfeucht and H. J. Hoogeboom and G. Rozenberg}, pages={315--328}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2 } @Article{CookP94, refkey={C1070}, title={A Denotational Semantics of Inheritance and Its Correctness}, author={William Cook and Jens Palsberg}, pages={329--350}, journal=iandcomp, month={1~} # nov, year=1994, volume=114, number=2, abstract={This paper presents a denotational model of inheritance. The model is based on an intuitive motivation of inheritance as a mechanism for deriving modified versions of recursive definitions. The correctness of the model is demonstrated by proving it equivalent to an operational semantics of inheritance based upon the method lookup algorithm of object-oriented languages.} } November 15, 1994 Volume 115, Number 1 @Article{VardiW94, refkey={C994}, title={Reasoning About Infinite Computations}, author={Moshe Y. Vardi and Pierre Wolper}, pages={1--37}, journal=iandcomp, month={15~} # nov, year=1994, volume=115, number=1, abstract={We investigate extensions of temporal logic by connectives defined by finite automata on infinite words. We consider three different logics, corresponding to three different types of acceptance conditions (finite, looping and repeating) for the automata. It turns out, however, that these logics all have the same expressive power and that their decision problems are all PSPACE-complete. We also investigate connectives defined by alternating automata and show that they do not increase the expressive power of the logic or the complexity of the decision problem.}, references={LICS::AlurH1990, TLS::BanieqbalB1989, TLS::BanieqbalBP1989, FMP::BarringerKP1985, POPL::BarringerKP1986, TCS::BrzozowskiL1980, PICLMPS::Buchi1960, JACM::ChandraKS1981, JCSS::Choueka1974, ICALP::EmersonC1980:169, JCSS::FischerL1979, POPL::GabbayPSS1980, TCS::HalpernR1983, MISC::Harel1979, MISC::Harel1984, JCSS::HarelKP1982, POPL::HarelP1978, TCS::HarelP1985, LICS::HarelRV1990, IC::HarelS1982, IC::HarelS1985, JCSS::Jones1975, TCS::Kaminski1985:217, TCS::Kozen1983, IC::Ladner1977, IEEETSE::Lamport1977, MST::Landweber1969, TCS::Leiss1981:323, WLP::LichtensteinPZ1985, LNCS::MannaP1989, TOPLAS::MannaW1984, IC::McNaughton1966, LOGIC::Meyer1975, AMSSCC::MeyerS1973, BOOK::Milner1980, TCS::MiyanoH1984, TCS::MoriyaY1988, FOCS::Muller1963, LICS::MullerSS1988, ACTAI::Nishimura1980, FOCS::Pnueli1977, POPL::PnueliR1989, FOCS::Pratt1976, FOCS::Pratt1979, JCSS::Pratt1980, WLP::Pratt1982, IBMJRD::RabinS1959, FOCS::Safra1988, TR::Shaw1979, THESIS::Sistla1983, JACM::SistlaC1985, TCS::SistlaVW1987, EIVK::Staiger1987, IC::Streett1982, IC::Thomas1979, IC::Thomas1981, HTCS::Thomas1990, BOOK::TrakhtenbrotB1973, FOCS::Vardi1985, WLP::Vardi1985, POPL::Vardi1988, WLP::VardiW1983, JCSS::VardiW1986, LICS::VardiW1986, IC::Wagner1979, THESIS::Wolper1982, IC::Wolper1983, TLS::Wolper1989} } @Article{WrightF94, refkey={C1210}, title={A Syntactic Approach to Type Soundness}, author={Andrew K. Wright and Matthias Felleisen}, pages={38--94}, journal=iandcomp, month={15~} # nov, year=1994, volume=115, number=1, abstract={We present a new approach to proving type soundness for Hindley/Milner-style polymorphic type systems. The keys to our approach are (1)~an adaptation of subject reduction theorems from combinatory logic to programming languages, and (2)~the use of rewriting techniques for the specification of the language semantics. The approach easily extends from polymorphic functional languages to imperative languages that provide references, exceptions, continuations, and similar features. We illustrate the technique with a type soundness theorem for the core of Standard ML, which includes the first type soundness proof for polymorphic exceptions and continuations.}, references={TOPLAS::AbadiCPP1991, BOOK::Barendregt1984, POPL::CrankF1991, BOOK::CurryF1958, POPL::DamasM1982, THESIS::Damas1985, TOPLAS::DonahueD1985, POPL::DubaHM1991, POPL::Felleisen1988, SCP::Felleisen1991:35, MISC::FelleisenF1986, TCS::FelleisenF1989, TCS::FelleisenFKD1987, TR::FelleisenH1989, TAMS::Hindley1969, BOOK::HindleyS1986, POPL::LeroyW1991, POPL::MacQueenPS1984, ICALP::MasonT1989, JCSS::Milner1978, TCS::MilnerT1991, POPL::MitchellH1988, TOPLAS::MitchellP1988, TCS::Plotkin1975:125, TR::Plotkin1981, THESIS::Reppy1991, ACMCP::Reynolds1972, ICALP::Reynolds1974, SICOMP::Scott1976, JSYML::Seldin1977, TR::TalpinJ1991, THESIS::Tofte1987, IC::Tofte1990:1, ESOP::Wright1992} } @Article{Fekete94, refkey={C902}, title={Asynchronous Approximate Agreement}, author={A. D. Fekete}, pages={95--124}, journal=iandcomp, month={15~} # nov, year=1994, volume=115, number=1, xxx-references={JACM::DolevDS87, JACM::DolevLPSW86, JACM::FischerLP85, JACM::HalpernM90, LundeliusL84, JACM::LamportM85, JACM::PeaseSL80, Welch87} } @Article{HoritaBR94, refkey={C1120}, title={Fully Abstract Denotational Models for Nonuniform Concurrent Languages}, author={E. Horita and J. W. de Bakker and J. J. M. M. Rutten}, pages={125--178}, journal=iandcomp, month={15~} # nov, year=1994, volume=115, number=1, xxx-references={JACM::AptP86, AmericaBKR89, Bakker91, BakkerZ82, JACM::BrookesHR84, GrooteV92, Hennessy83, JACM::Hennessy85} } December 1994 Volume 115, Number 2 @Article{AcetoH94, refkey={C1333}, title={Adding Action Refinement to a Finite Process Algebra}, author={L. Aceto and M. Hennessy}, pages={179--247}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={In this paper we present a Process Algebra for the specification of concurrent, communicating processes, in addition to the usual operators for communication, non-determinism, internal actions, and restrictions, and study a suitable notion of semantic equivalence for it. We argue that action refinements should not, in some formal sense, interfere with the internal evolution of processes and their application to processes should consider the restriction operator as a ``binder.'' We show that, under the above assumptions, the weak version of the refine equivalence introduced by Aceto and Hennessy ((1993) {\em Information and Computation\/} {\bf103}, 204--269) is preserved by action refinements and, moreover, is the largest such equivalence relation contained in weak bisimulation equivalence. We also discuss an example showing that, contrary to what happens in Aceto and Hennessy ((1993) {\em Information and Computation\/} {\bf103}, 204--269), refine equivalence and timed equivalence are different notions of equivalence over the language considered in this paper.}, xxx-references={LICS::AcetoH89, AcetoH93, JACM::AcetoH92, BergstraK84, JACM::BrookesHR84}, full-xxx-references={LICS::AcetoH89, AcetoH93, JACM::AcetoH92, BergstraK84, TCS::BergstraK85, TCS::BoudolC88, JACM::BrookesHR84, TCS::NicolaH84, TCS::Stoughton88} } @Article{HausslerLW94, refkey={C1175}, title={Predicting $\{0,1\}$-Functions on Randomly Drawn Points}, author={D. Haussler and N. Littlestone and M. K. Warmuth}, pages={248--292}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={We consider the problem of predicting $\{0,1\}$-valued functions on ${\bf R}^n$ and smaller domains, based on their values on randomly drawn points. Our model is related to Valiant's PAC learning model, but does not require the hypotheses used for prediction to be represented in any specified form. In our main result we show how to construct prediction strategies that are optimal to within a constant factor for any reasonable class~$F$ of target functions. This result is based on new combinatorial results about classes of functions of finite VC dimension. We also discuss more computationally efficient algorithms for predicting indicator functions of axis-parallel rectangles, more general intersection closed concept classes, and halfspaces in ${\bf R}^n$. These are also optimal to within a constant factor. Finally, we compare the general performance of prediction strategies derived by our method to those derived from methods in PAC learning theory.}, xxx-references={FOCS::Blum90a, JACM::BlumerEHW89, EhrenfeuchtH89, EhrenfeuchtHKV89, Haussler92, HausslerKLW91, JACM::KearnsLV94, JACM::KearnsV94, LittlestoneW94, STOC::Natarajan87, JACM::PittV88} } @Article{MayerS94, refkey={C1234}, title={Word Problems---This Time with Interleaving}, author={Alain J. Mayer and Larry J. Stockmeyer}, pages={293--311}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={We consider regular expressions extended with the interleaving operator, and investigate the complexity of membership and inequivalence problems for these expressions. For expressions using the operators union, concatenation, Kleene star, and interleaving, we show that the inequivalence problem (deciding whether two given expressions do not describe the same set of words) is complete for exponential space. Without Kleene star, we show that the inequivalence problem is complete for the class $\Sigma_2^p$ at the second level of the polynomial-time hierarchy. Certain cases of the membership problem (deciding whether a given word is in the language described by a given expression) are shown to be NP-complete. It is also shown that certain languages can be described exponentially more succinctly by using interleaving.}, xxx-references={KanellakisS90, FOCS::MeyerS72, STOC::StockmeyerM73}, full-xxx-references={KanellakisS90, FOCS::MeyerS72, TCS::Stockmeyer77, STOC::StockmeyerM73, TCS::Wrathall77} } @Article{Upfal94, refkey={C1315}, title={Tolerating a Linear Number of Faults in Networks of Bounded Degree}, author={Eli Upfal}, pages={312--320}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={Dwork et al. [{\em SIAM J. Comput.} {\bf17} (1988), 975--988] proposed a new paradigm for fault tolerant distributed computing termed {\em almost everywhere agreement}. While all other fault tolerance paradigms require networks of high connectivity to tolerate substantial number of faults, it was shown in Dwork {\em et al.}\ that the new paradigm can be achieved even on bounded degree networks, as long as the number of faults is bounded by $O(n/\log n )$, where $n$ is the size of the network. A major problem that was left open in Dwork {\em et al.}\ is whether almost everywhere agreement can be achieved on bounded degree networks in the presence of up to $O(n)$ faulty nodes (processors). In this work we answer this question in the affirmative. As in Dwork {\em et al.}, our solution is based on a general technique for simulating on a bounded degree network an algorithm designed for the complete network. Each communication round of the complete network protocol is simulated by a logarithmic number of communication rounds, and with a polynomial number of messages.}, xxx-references={DolevFFLS82, STOC::LubotzkyPS86} } @Article{KolaitisT94, refkey={C1136}, title={Logical Definability of {NP} Optimization Problems}, author={Phokion G. Kolaitis and Madhukar N. Thakur}, pages={321--353}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={We investigate here NP optimization problems from a logical definability standpoint. We show that the class of optimization problems whose optima are definable using first-order formulae coincides with the class of polynomially bounded NP optimization probles on finite structures. After this, we analyze the relative expressive power of various classes of optimization problems that arise in this framework. Some of our results show that logical definability has different implications for NP maximization problems than it has for NP minimization problems, in terms of both expressive power and approximation properties.}, xxx-references={FOCS::AroraLMSS92, FOCS::AroraS92, CrescenziP91, STOC::KolaitisV87}, full-xxx-references={FOCS::AroraLMSS92, FOCS::AroraS92, CrescenziP91, STOC::KolaitisV87, TCS::LeggettM81, TCS::PazM81, TCS::Stockmeyer76, TCS::Wagner86} } @Article{GrooteH94, refkey={C1272}, title={Undecidable Equivalences for Basic Process Algebra}, author={Jan Friso Groote and Hans H{\"u}ttel}, pages={354--371}, journal=iandcomp, month=dec, year=1994, volume=115, number=2, abstract={A recent theorem shows that strong bisimilarity is decidable for the class of {\em normed\/} BPA processes, which correspond to a class of context-free grammars generating the $\epsilon$-free context-free languages. Huynh and Tian (Technical Report UTDCS-31-90, University of Texas at Dallas, 199) have shown that readiness and failure equivalence are undecidable for BPA processes. In this paper we examine all other equivalences in the linear/branching time hierarchy and show that {\em none\/} of them are decidable for normed BPA processes.}, xxx-references={BergstraK84, JACM::BrookesHR84, LICS::ChristensenHM93, GrooteV92, LICS::HuttelS91, KanellakisS90, FOCS::KorenjakH66, FOCS::RoundsB81}, full-xxx-references={TCS::Abramsky87, BergstraK84, JACM::BrookesHR84, LICS::ChristensenHM93, TCS::Engelfriet85, TCS::Friedman76, GrooteV92, LICS::HuttelS91, KanellakisS90, FOCS::KorenjakH66, TCS::Philips87, FOCS::RoundsB81} } January 1995 Volume 116, Number 1 @Article{Smid95, refkey={C1197}, title={Dynamic Rectangular Point Location, with an Application to the Closest Pair Problem}, author={Michiel Smid}, pages={1--9}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={In the $k$-dimensional rectangular point location problem, we have to store a set of $n$ non-overlapping axes-parallel hyperrectangles in a data structure, such that the following operations can be performed efficiently: point location queries, insertions and deletions of hypperrectangles, and splitting and merging of hyperrectangles. A linear size data structure is given for this problem, allowing queries to be solved in $O((\log n)^{k-1}\log\log n)$ time, and allowing the four update operations to be performed in $O((\log n)^2\log\log n)$ amortized time. If only queries, insertions and split operations have to be supported, the $\log\log n$ factors disappear. The data structure is based on the skewer tree of Edelsbrunner, Haring and Hilbert and uses dynamic fractional cascading. \par This result is used to obtain a linear size data structure that maintains the closest pair in a set of $n$ points in $k$-dimensional space, when points are inserted. This structure has an $O((\log n)^{k-1})$ amortized insertion time. This leads to an on-line algorithm for computing the closest pair in a point set in $O(n(\log n)^{k-1})$ time. In the planar case, these two latter results are optimal.}, references={ALGOR::ChazelleG1986:133, FOCS::DobkinS1989, BOOK::Edelsbrunner1987, COMPJ::EdelsbrunnerHH1986, ALGOR::MehlhornN1990, BOOK::Overmars1983, BOOK::PreparataS1985, ALGR::Smid1991, CCCG::Smid1990, DISCG::Smid1992, SODA::Supowit1990, DISCG::Vaidya1989} } @Article{Huth95, refkey={C1316}, title={A Maximal Monoidal Closed Category of Distributive Algebraic Domains}, author={Michael Huth}, pages={10--25}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={We study the category BC of bounded complete dcpos and maps preserving all suprema (linear maps). BC is a symmetric monoidal closed category. If SUP denotes the full subcategory of BC with dcpos with one as objects, we realize a categorical semantics for linear logic in SUP. The multiplicatives are {\em fully distributive\/} wrt.\ the additives. Given PRIME, the full subcategory of BC with prime-algebraic dcpos as objects, we introduce a {\em prime-algebraic\/} quotient $\Pi(A)$ which preserves all the logical operations in SUP up to isomorphism. Therefore, if $C$ is a categorical semantics in BC, then $\Pi(C)$ is a categorical semantics in PRIME. In particular, $\Pi$(SUP), the full subcategory of BC with all prime-algebraic lattices as objects, is such a categorical semantics. PRIME is symmetric monoidal closed and maximal with respect to being closed under --$\circ$ and $\perp$, if we demand that all objects are algebraic and distributive. Thus, $\Pi$(SUP) is a maximal categorical semantics with respect to these conditions. We discuss the modalities !(\_) and ?(\_) in SUP.}, references={APAL::Abramsky1991, CANMB::BanaschewskiN1976, MSCS::Barr1991, MISC::Erne1990, BOOK::GierzHKLMS1980, TCS::Girard1987, BOOK::GirardLT1989, HTCS::GunterMS1990, BOOK::Hoofman1992, TCS::HuwigP1990, BOOK::Johnstone1982, BOOK::Jung1989, MFPS::JungLP1991, BOOK::Lane1971, MISC::Marti-OlietM1991, IJFCS::Marti-OlietM1992, MFPS::MeltonSS1991, ANNDM::Mislove1984, BOOK::Schmidt1986, LNM::Scott1972, ICALP::Scott1982, TCS::Smyth1983, BOOK::Troelstra1983, TCS::Winskel1985, LNCS::Winskel1988, BOOK::Zhang1991, MFPS::Zhang1991, IC::Zhang1992:151} } @Article{CamilleriW95, refkey={C1266}, title={{CCS} with Priority Choice}, author={Juanito Camilleri and Glynn Winskel}, pages={26--37}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={This paper investigates an extension of Milner's {\sc ccs} with a priority choice operator called prisum: this operator is very similar to the PRIALT construct of Occam. The new binary prisum operator only allows execution of its second component in the case where the environment is not ready to allow the first component to proceed. This dependency on the set of actions the environment is ready to perform goes beyond that encountered in traditional {\sc ccs}. Its expression leads to a novel operational semantics in which transitions carry ready-sets (of the environment) as well as the normal action symbols from {\sc ccs}. A notion of strong bisimulation is defined on agents with priority via this semantics. It is a congruence and satisfies new equational laws (including a new expansion law) which are shown to be complete for finite agents with prisum. The laws are conservative over agents of traditional {\sc ccs}.}, references={MFPS::Barrett1989, CWI::BaetenBK1985, TR::BestK1990, MISC::Brinksma1986, IJPP::Camilleri1989, THESIS::Camilleri1990, CONCUR::Camilleri1991, LICS::CamilleriW1991, IC::CleavelandH1990:58, MFCS::CostaS1984, CONCUR::GerberL1990, CONCUR::Groote1990, BOOK::inmos1984, CAV::Jensen1991, BOOK::Milner1989, CONCUR::SmolkaS1990, CONCUR::Tofts1990} } @Article{Thomsen95, refkey={C1219}, title={A Theory of Higher Order Communicating Systems}, author={Bent Thomsen}, pages={38--57}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={{\em A Calculus of Higher Order Communicating Systems\/} was presented in Thomsen [1989]. This calculus considers sending and receiving processes to be as fundamental as nondeterminism and parallel composition. In this paper we present an investigation of the foundation of the theory of this calculus, together with the full proofs of all major theorems. \par The calculus called CHOCS is an extension of Milner's CCS in the sense that all the constructions of CCS are included or may be derived from more fundamental constructs. Most of the mathematical framework of CCS carries over almost unchanged. The operational semantics of CHOCS is given as a labelled transition system and it is a direct extension of the semantics of CCS with value passing. A set of algebraic laws satisfied by the calculus is presented. These are similar to the CCS laws only introducing obvious extra laws for sending and receiving processes. The power of process passing is underlined by a result showing that recursion can be simulated by means of process passing and communication.}, references={TCS::Abramsky1987, LICS::Abramsky1987, MISC::Abramsky1988, IC::Abramsky1991:161, MISC::Abramsky1990, STACS::AstesianoGR1988, TAPSOFT::AstesianoR1987, TCS::AustryB1984, TAPSOFT::Boudol1988, MISC::Christensen1988, POPL::CousotC1979, TAPSOFT::GiacaloneP1989, MISC::GrooteV1989, JACM::HennessyM1985:137, LNCS::HennessyN1987, BOOK::Hoare1985, MISC::KennawayS1988, BOOK::Milner1980, JCSS::Milner1984, TCS::Milner1983, IP::Milner1986, BOOK::Milner1989, IC::MilnerPW1992:1, PARLE::Nielson1988, LNCS::Park1981, TR::Plotkin1981, FOCS::Pnueli1977:46, POPL::Thomsen1989, THESIS::Thomsen1990, LICS::Walker1988:186} } @Article{NerodeNS95, refkey={C1302}, title={Computing Circumscriptive Databases: {I}. Theory and Algorithms}, author={Anil Nerode and Raymond T. Ng and V. S. Subrahmanian}, pages={58--80}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={Though circumscription was introduced by McCarthy over a decade ago, there has been relatively little work on algorithms for computing circumscriptive databases. In this paper, we develop algorithms to compute the preferred models of circumscriptive databases at compile-time using mixed integer linear programming techniques. Two advantages of this (bottom-up) approach are that it makes efficient re-use of previous computations and it provides much faster run-time performance. Some other advantages of using linear programming to automate deduction at compile time is that its re-optimization facilities elegantly accommodate database updates and also that it leads to a completely declarative formulation in which ordering of rules and literals in rule bodies plays no real role. Finally, we plan to use a standard relational database system as our run-time environment; this should yield relatively fast run-time processing, and provide a more expressive query language in which aggregates and the like can be expressed easily.}, references={IEEECS::AstromBCCLV1991, TR::AraqueC1991, PODS::BancilhonMSU1986, SIGMOD::BancilhonR1986, PODS::BeeriR1987, TR::BellNNS1991, PODS::BellNNS1992, COR::BlairJL1988, AAAI::CadoliL1990, IEEECDC::CainesW1991, JACM::ChandruH1991:205, STOC::CosmadakisGKV1988, TCS::EiterG1993:231, MISC::EmeryNS1992, COMPI::EtheringtonMR1985, BOOK::Etherington1988, ICSLP::GelfondL1988:1070, ICSLP::GelfondL1988:579, ARTII::Ginsberg1989, BOOK::Hailperin1976, BOOK::HillierL1974, ANNMAI::HookerF1990, POPL::JaffarL1987, DSS::Jeroslow1988, COMB::Karmarkar1984, DOKAN::Khachian1979, ILPS::KempSS1991, CACM::Kohn1991:64, SCACSD::KohnN1992, JACM::KolaitisP1990:1, IPL::Krishnaprasad1988, IJCAI::Lifschitz1985, ARTII::Lifschitz1985, AAAI::Lifschitz1986, ANNMAI::MarekNR1990, ARTII::McCarthy1980, ARTII::McCarthy1986, ARTII::MinkerP1986, ARTII::Moore1985, ICLP::MorrisUG1986, AAAI::Przymusinski1986, ACMTDS::Roussopoulos1991, APAL::Schlipf1987, PODS::ShmueliTZ1988, PODS::Ullman1989} } @Article{Abe95, refkey={C1036}, title={Characterizing {PAC}-Learnability of Semilinear Sets}, author={Naoki Abe}, pages={81--102}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={The learnability of the class of letter-counts of regular languages (semilinear sets) and other related classes of subsets of ${\bf N}^d$ with respect to the distribution-free learning model of Valiant (PAC-learning model) is characterized. Using the notion of reducibility among learning problems due to Pitt and Warmuth called ``prediction preserving reducibility,'' and a special case thereof, a number of positive and partially negative results are obtained. On the positive side the class of semilinear sets of dimension 1 or 2 is shown to be learnable when the integers are encoded in unary. On the neutral to negative side it is shown that when the integers are encoded in binary the learning problem for semilinear sets as well as a class of subsets of ${\bf Z}^d$ much simpler than semilinear sets is as hard as learning DNF, a central open problem in the field. A number of hardness results for related learning problems are also given.}, references={Angluin1978:337, Angluin1987:87, EhrenfeuchtHKV1989:247, Gold1967:447, Gold1978:302, HausslerKLW1991:129, FOCS::HausslerLW1988, OshersonW1982:123, STOC::PittW1989} } @Article{ImmermanL95, refkey={C1185}, title={The Complexity of Iterated Multiplication}, author={Neil Immerman and Susan Landau}, pages={103--116}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={For a monoid $G$, the iterated multiplication problem is the computation of the product of $n$ elements from $G$. By refining known completeness arguments, we show that as $G$ varies over a natural series of important groups and monoids, the iterated multiplication problems are complete for most natural, low-level complexity classes. The completeness is with respect to ``first-order projections''---low-level reductions that do not obscure the algebraic nature of these problems.}, xxx-references={Cai90, STOC::Cook71, Cook85, FOCS::HartmanisIM78, FOCS::Toda89} } @Article{Eberly95, refkey={C1124}, title={Fast Parallel Band Matrix Arithmetic}, author={Wayne Eberly}, pages={117--127}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={Fast parallel algorithms are presented for computation of the determinant, adjoint, characteristic polynomial and rank of band matrices, and for the solution of systems of linear equations with band matrices as coefficient matrices. The algorithms can be implemented using arithmetic-boolean circuits of polynomial size and depth $O(\log n \log m)$, or depth $O(\log n \log m + \log n \log \log n)$ for computations over small finite fields, where $n$ is the order and $m$ the band width of the matrix given as input. They can be implemented for computations over number fields and finite fields using log space uniform boolean circuits of depth $O(\log n \log m + \log n \log \log n)$ and polynomial size, for input size $n$ and band width~$m$. While they are not processor efficient, these algorithms can be implemented using circuits of asymptotically smaller depth than previous algorithms for these problems.}, xxx-references={BorodinGH82, FOCS::KaltofenP92, STOC::PanR85} } @Article{SheinwaldLZ95, refkey={C1354}, title={On Encoding and Decoding with Two-Way Head Machines}, author={Dafna Sheinwald and Abraham Lempel and Jacob Ziv}, pages={128--133}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={Ziv and Lempel (1978) investigated the encoding power of finite state machines with respect to given individual sequences. Motivated by the study of various kinds of machines as recognizers of formal languages (cf. Hopcroft and Ullman, 1979), we compare the encoding and decoding power of finite state sequential machines and the following extensions thereof. First, we show that, with a forward moving head, the best compression ratio achievable for a given sequence, to be decoded by a finite state decoder, is the same as the best ratio attainable for that sequence when encoded by a finite state encoder to move its head back and forth on an input sequence, even if the decoder has unrestricted power. However, better compression can be achieved for specific infinite sequences using an unrestricted encoder and a two-way finite state decoder.} } @Article{DiekertGP95, refkey={C1360}, title={Rational and Recognizable Complex Trace Languages}, author={Volker Diekert and Paul Gastin and Antoine Petit}, pages={134--153}, journal=iandcomp, month=jan, year=1995, volume=116, number=1, abstract={Mazurkiewicz defined traces as an algebraic model of finite concurrent processes. In order to modelize non-terminating processes a good notion of infinite trace was needed, which finally led to the notion of complex trace. For complex traces an associative concatenation and an $\omega$-iteration are defined. \par This paper defines and investigates rational and recognizable complex trace languages. We prove various closure results such as the closure under boolean operations (for recognizable languages), concatenation, and left and right quotients by recognizable sets. Then we study sufficient conditions ensuring the recognizability of the finite and infinite iterations of complex trace languages. We introduce a generalization of the notion of concurrent iteration which leads to the main result of the paper: the generalization of Kleene's and Ochmanski's theorems to complex trace languages.}, xxx-references={ClerboutL87} } February 1, 1995 Volume 116, Number 2 @Article{FleischerJM95, refkey={C1183}, title={A Communication-Randomness Tradeoff for Two-Processor Systems}, author={Rudolf Fleischer and Hermann Jung and Kurt Mehlhorn}, pages={155--161}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={We present a tight tradeoff between the expected communication complexity $\bar{C}$ (for a two-processor system) and the number $R$ of random bits used by any Las Vegas protocol for the list-nondisjointness function of two lists of $n$ numbers of $n$ bits each. This function evaluates to $1$ if and only if the two lists correspond in at least one position. We show a $\log(n^2/\bar{C})$ lower bound on the number of random bits used by any Las Vegas protocol, $\Omega(n)\le\bar{C}\le O(n^2)$. We also show that expected communication complexity $\bar{C}$, $\Omega(n\log n) \le\bar{C}\le O(n^2)$, can be achieved using no more than $\log(n^2/\bar{C}) + \lceil\log(2+\log(n^2/\bar{C}))\rceil+6$ random bits.}, xxx-references={STOC::AhoUY83, FOCS::CanettiG90, STOC::Furer87, STOC::HalstenbergR88, STOC::KrizancPU88, FOCS::LovaszS88, STOC::MehlhornS82, STOC::PapadimitriouS82, FOCS::Yao77, STOC::Yao79, FOCS::Yao83} } @Article{Tamm95, refkey={C1186}, title={Communication Complexity of Sum-Type Functions Invariant under Translation}, author={Ulrich Tamm}, pages={162--173}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={The communication complexity of a function $f$ denotes the number of bits that two processors have to exchange in order to compute $f(x,y)$, when each processor knows one of the variables $x$ and $y$, respectively. \par In this paper the deterministic communication complexity of sum--type functions, such as the Hamming distance and the Lee distance, is examined. Here $f:{\cal X} x {\cal X} \longrightarrow G$, where ${\cal X}$ is a finite set and $G$ is an Abelian group, and the sum--type function $f_{n}:{\cal X}^{n}x{\cal X}^{n} \longrightarrow G$ is defined by \[ f_{n}((x_{1}, \ldots ,x_{n}),(y_{1}, \ldots ,y_{n})) = \sum_{i=1}^{n} f(x_{i},y_{i}). \] Since the functions examined are also translation--invariant, their function matrices are simultaneously diagonalizable and the corresponding eigenvalues can be calculated. This allows to apply a rank lower bound for the communication complexity. \par The best results are obtained for $G = Z/2Z$. For prime numbers $\mid {\cal X} \mid$ in this case the communication complexity of all non--trivial sum--type functions is determined exactly. Exact results are also obtained for the parity of the Hamming distance and the parity of the Lee distance. For the Hamming distance and the Lee distance exact results are only obtained for special parameters $n$ and $\mid {\cal X} \mid$.}, xxx-references={STOC::MehlhornS82, STOC::Yao79} } @Article{CaseJS95, refkey={C1356}, title={Complexity Issues for Vacillatory Function Identification}, author={John Case and Sanjay Jain and Arun Sharma}, pages={174--192}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={It was previously shown by Barzdin and Podnieks that one does {\em not\/} increase the power of learning programs for {\em functions\/} by allowing learning algorithms to converge to a finite set of correct programs instead of requiring them to converge to a single correct program. In this paper we define some new, subtle, but natural concepts of mind change complexity for function learning and show that, if one bounds this complexity for learning algorithms, then, by contrast with Barzdin and Podnieks result, there are interesting and sometimes complicated tradeoffs between these complexity bounds, bounds on the number of final correct programs, and learning power.}, xxx-references={BlumB75, Chen82, DaleyS86, Gold67, Gold78, OshersonW82} } @Article{Schneider95, refkey={C1342}, title={An Operational Semantics for Timed {CSP}}, author={Steve Schneider}, pages={193--213}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={An operational semantics is defined for the language of timed CSP, in terms of two relations: an evolution relation, which describes when a process becomes another simply by allowing time to pass; and a timed transition relation, which describes when a process may become another by performing an action at a particular time. It is shown how the timed behaviours used as the basis for the denotational models of the language may be extracted from the operational semantics. Finally, the failures model for timed CSP is shown to be equivalent to may-testing, and thus to trace congruence.}, xxx-references={KoymansSRGA88} } @Article{Yamakami95, refkey={C1009}, title={Feasible Computability and Resource Bounded Topology}, author={Tomoyuki Yamakami}, pages={214--230}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={Mike Townsend introduced a resource-bounded extension of the polynomial-time computable functions on strings to type-two functionals, and studied a type-two version of the Meyer-Stockmeyer polynomial hierarchy which is founded on polynomial-time computable functionals of type two. A functional of type two is a polynomial-time computable if it is computed by a deterministic function-oracle Turing machien whose runtime is bounded by a polynomial that does not depend on the choice of oracle functions. Townsend also introduced a boldface polynomial hierarchy of type two by a relativization method, and gave a ``topological'' characterization of the first level of this hierarchy. We reformulate Townsend's topological notions associated with time bounded computations of function-oracle Turing machines, and further extend his ``topological'' characterization to all levels of the boldface polynomial hierarchy of type two. This leads to a polynomialized version of descriptive set theory.}, xxx-references={STOC::Constable73, STOC::Cook75, FOCS::CookK89, STOC::CookU89, FOCS::Mehlhorn73, FOCS::Yao85}, full-xxx-references={STOC::Constable73, STOC::Cook75, FOCS::CookK89, STOC::CookU89, TCS::HartmanisH89, TCS::Ko85, TCS::KoF82, FOCS::Mehlhorn73, TCS::Stockmeyer76, FOCS::Yao85} } @Article{FulopV95, refkey={C1284}, title={Attributed Tree Transducers Cannot Induce all Deterministic Bottom-Up Tree Transformations}, author={Zolt{\'a}n F{\"u}l{\"o}p and S{\'a}ndor V{\'a}gv{\"o}lgyi}, pages={231--240}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={In this paper we give a deterministic bottom-up tree transducer~$T$ and show that the tree transformation $\tau(T)$ induced by it can be induced by no attributed tree transducer.}, full-xxx-references={TCS::CourcelleF82, TCS::FulopHVV9+} } @Article{GrahneM95, refkey={C1351}, title={Updates and Subjunctive Queries}, author={G{\"o}sta Grahne and Alberto O. Mendelzon}, pages={241--252}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={A subjunctive query of the form $\phi > \psi$ means `if $\phi$ were true in the knowledgebase, would $\psi$ also necessarily be true?' We propose the following semantics for subjunctive queries: $\phi > \psi$ will hold in the current knowledgebase {\tt T} if $\psi$ holds in the result of updating {\tt T} with $\phi$. This is known as the {\em Ramsey test\/} in philosophy. We adapt the {\em model checking approach\/} of Halpern and Vardi: A knowledgebase is a finite set of finite sets of positive facts interpreted in a closed world setting. We then use Winslett's possible models approach to give semantics to knowledgebase updates, and we introduce a query language which is essentially propositional logic, augmented with a subjunctive conditional that has an intensional interpretation in our model. We show that query answering and update can be performed in time polynomial in the size of the knowledgebase. However, query equivalence is shown to be complete in polynomial space, and this is also the complexity of query answering as a function of query size. We give a sound axiomatization of query equivalence and show that the update operator satisfies the postulates for updates adapted by Katsuno and Mendelzon from the Alchourr\'{o}n-G\"{a}rdenfors-Makinson belief revision postulates.} } @Article{Walker95, refkey={C1359}, title={Objects in the {$\pi$}-Calculus}, author={David Walker}, pages={253--271}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={Two semantics for a parallel object-oriented programming language are presented. One is a two-level transitional semantics in which the global behaviour of a system is derived directly from the possible actions of its constituent objects. The other is by translation into the $\pi$-calculus. A close correspondence between the semantics is established.}, xxx-references={AmericaBKR89, MilnerPW92a, MilnerPW92b} } @Article{Amadio95, refkey={C1378}, title={A Quick Construction of a Retraction of All Retractions for Stable Bifinites}, author={Roberto M. Amadio}, pages={272--274}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={In the framework of stable domain theory we show that the space of retractions over a bifinite is a retract of the functional space.}, xxx-references={Berardi91, LICS::Jung90} } @Article{Courcelle95, refkey={C1431}, title={Structural Properties of Context-Free Sets of Graphs Generated by Vertex Replacement}, author={Bruno Courcelle}, pages={275--293}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={We establish that a VR (``Vertex Replacement'') set of graphs, i.e., a set of graphs generated by a C-edNCE or, equivalently, by a separated handle rewriting graph grammar is HR (``Hyperedge Replacement''), i.e., is generated by a hyperedge replacement graph grammar, if and only if its graphs do not contain arbitrary large complete bipartite graphs as subgraphs. Another equivalent condition is that its graphs have a number of edges that is linearly bounded in terms of the number of vertices. These properties are decidable by means of an appropriate extension of the theorem by Parikh that characterizes the commutative images of context-free languages. We also extend these results to hypergraphs.}, xxx-references={Courcelle90, EngelfrietR90, RozenbergW86} } @Article{Riecke95, refkey={C1301}, title={Statman's 1-Section Theorem}, author={Jon G. Riecke}, pages={294--303}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={Statman's 1-Section Theorem (R. Statman, 1985a) is an important but little-known result in the model theory of the simply-typed $\lambda$-calculus. The 1-Section Theorem states a necessary and sufficient condition on models of the simply-typed $\lambda$-calculus for determining whether $\beta\eta$-equational reasoning is {\em complete\/} for proving equations that hold in a model. We review the statement of the theorem, give a detailed proof, and discuss its significance.}, xxx-references={LICS::BergerS91, Meyer82, Statman85} } @Article{FangR95, refkey={C1240}, title={Entropy Optimization Models with Convex Constraints}, author={S. C. Fang and J. R. Rajasekera}, pages={304--311}, journal=iandcomp, month={1~} # feb, year=1995, volume=116, number=2, abstract={In this paper, we study the minimum cross-entropy optimization problem subject to a general class of convex constraints. Using a simple geometric inequality and the conjugate inequality we demonstrate how to directly construct a ``partial'' geometric dual program which allows us to apply the dual perturbation method to derive the strong duality theorem and a dual-to-primal conversion formula. This approach generalizes the previous results of linearly, quadratically, and entropically constrained cross-entropy optimization problems and provides a platform for using general purpose optimizers to generate ``epsilon-optimal'' solution pairs to the problem.} } February 15, 1995 Volume 117, Number 1 @Article{KurshanM95, refkey={C1289}, title={A Structural Induction Theorem for Processes}, author={R. P. Kurshan and K. L. McMillan}, pages={1--11}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={This paper deals with the formal verification of finite state systems that have an arbitrary number of isomorphic components. We present a technique for inductively generalizing tests on a system of fixed size in order to show that a system of arbitrary size satisfies a given specification. This makes it possible to use finite state verification systems, such as COSPAN, to verify parameterized protocols. The method also may be useful for verifying systems of fixed but large size, since it reduces the size of the system that must be checked automatically. The basis of the method is a {\em structural induction theorem\/} for processes, which is stated and proved in this paper. The theorem applies to a variety of process formalisms satisfying simple algebraic laws. We give examples of proofs using the Calculus of Communicating Systems (CCS) and the $s/r$ model.}, xxx-references={JACM::GermanS92, LICS::Walker88} } @Article{BuningKF95, refkey={C1125}, title={Resolution for Quantified {Boolean} Formulas}, author={Hans Kleine B{\"u}ning and Marek Karpinski and Andreas Fl{\"o}gel}, pages={12--18}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={A complete and sound resolution operation directly applicable to the quantified boolean formulas is presented. If we restrict the resolution to unit resolution, then the completeness and soundness for extended quantified Horn formulas is shown. We prove that the truth of a quantified Horn formula can be decided in $O(rn)$ time, where $n$ is the length of the formula and $r$ is the number of universal variables, whereas in contrast the evaluation problem for extended quantified Horn formulas is coNP--complete for formulas with prefix $\forall \exists$. Further we show that the resolution is exponential for extended quantified Horn formulas.}, xxx-references={STOC::StockmeyerM73} } @Article{Ben-AmramG95, refkey={C1180}, title={On the Power of the Shift Instruction}, author={Amir M. Ben-Amram and Zvi Galil}, pages={19--36}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={This paper examines the power of the shift primitive when included in a high level model operating on unbounded integers. It is shown that in such a model a constant number of registers suffices for simulating an unbounded memory RAM of the same instruction set. The simulation is on-line, and its cost can be bounded by $O(t\alpha(s))$, for a RAM program of running time~$t$ and space~$s$. By multitask programming (postponing lengthy updates) it can be made close to real-time ($O(\alpha(s))$ per operation).}, xxx-references={STOC::AggarwalACS87, JACM::Ben-AmramG92, STOC::BertoniMS81, FOCS::HartmanisS74, STOC::PrattRS74, STOC::Simon81, STOC::Tarjan77} } @Article{LausenS95, refkey={C933}, title={Safety by Uninterpreted Locks}, author={Georg Lausen and Eljas Soisalon-Soininen}, pages={37--49}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={Locking of a static set of database transactions is discussed in the setting of uninterpreted locks. Uninterpreted locsk generalize entity locks to the case that any variable may be used for locking, not only those assoicated with the entities accessed by the transactions. A new condition for safe lockings is prestented. There exist safe lockings which fulfill the condition and accept a set of serializable schedules which could not be accepted by any safe locking in the entity lock model. Moreover, it is shown that the condition is necessary for safety whenever only entity locks are used. It is also shown that there are safe sets of locked transactions not satisfying the condition. This implies that safe locking by uninterpreted locks is too powerful to be completely characterized by our condition; however, our condition is more powerful than safe locking in the entity lock model. The given condition for safety is expressed in geometric terms and it can be used for proving the safety of specific lock policies. In particular, safe pre-analysis lock policies can be designed which strictly dominate the 2-phase lock policy with respect to the sets of accepted schedules.}, xxx-references={LausenSW86, JACM::Papadimitriou79b, JACM::Papadimitriou82, JACM::Yannakakis82, JACM::Yannakakis84, FOCS::YannakakisPK79} } @Article{HowellV95, refkey={C1215}, title={On Non-Preemptive Scheduling of Recurring Tasks Using Inserted Idle Times}, author={Rodney R. Howell and Muralidhar K. Venkatrao}, pages={50--62}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We consider the problem of non-preemptively scheduling periodic and sporadic task systems on one processor using inserted idle times. For periodic task systems, we prove that the decision problem of determining whether a periodic task system is schedulable for all start times with respect to the class of algorithms using inserted idle times is NP-Hard in the strong sense, even when the deadlines are equal to the periods. We then show that if there exists a polynomial time scheduling algorithm which correctly schedules a periodic task system $T$ whenever $T$ is feasible for all start times, then P=NP. We also prove that with respect to the same class of algorithms, the problem of determining whether there exist start times for which a periodic task system is feasible is also NP-Hard in the strong sense even when the deadlines are equal to the periods. The second part of the paper concentrates on sporadic task systems and inserted idle times. It seems reasonable to suppose that to insert idle times properly, knowledge of future releases of tasks is required. Thus, inserted idle times should not be expected to have much use in scheduling sporadic task systems. We provide a formal basis to these intuitions by proving that if a sporadic task system is schedulable by an online algorithm that uses inserted idle times, then it is schedulable by an online algorithm that does not use inserted idle times. We also prove that there cannot exist an optimal on-line inserted idle time algorithm for scheduling sporadic task systems, even if the deadlines correspond to the minimum separation time between successive releases of the same task. We conclude by considering the amount of look-ahead needed to schedule sporadic tasks correctly.}, xxx-references={JACM::LiuL73} } @Article{KimL95, refkey={C1269}, title={Node Replacement Graph Languages Squeezed with Chains, Trees, and Forests}, author={Changwook Kim and Dong Hoon Lee}, pages={63--77}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We present results on language-theoretic properties (such as closure, membership, and other decision properties) of node replacement graph languages (such as NLC, B-NLC, and Lin-NLC languages) squeezed with chains, trees, and forests.}, xxx-references={EngelfrietL89, EngelfrietR90, RozenbergW86, JACM::Sudborough75, JACM::Sudborough78}, full-xxx-references={TCS::Courcelle87, HTCS::Courcelle90, TCS::EhrenfeuchtMR84, TCS::EngelfrietL88, EngelfrietL89, TCS::EngelfrietLR91, EngelfrietR90, TCS::JanssensR82, HTCS::Johnson90, TCS::KimL9+, RozenbergW86, JACM::Sudborough75, JACM::Sudborough78} } @Article{IduryS95, refkey={C1433}, title={Multiple Matching of Rectangular Patterns}, author={Ramana M. Idury and Alejandro A. Sch{\"a}ffer}, pages={78--90}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We describe the first worst-case efficient algorithm for simultaneously matching multiple rectangular patterns of varying sizes and aspect ratios in a rectangular text. Efficient means significantly more efficient asymptotically than applying known algorithms, that handle one height (or width or aspect ratio) at a time, for each height. Our algorithm features an interesting use of multidimensional range searching, as well as new adaptations of several known techniques for two dimensional string matching. We also extend our algorithm to a dynamic setting where the set of patterns can change over time.}, xxx-references={STOC::AmirBF92, FOCS::AmirF91, STOC::DietzS87, STOC::GabowBT84, FOCS::GalilP92} } @Article{Shmueli95, refkey={C1297}, title={A Single Recursive Predicate is Sufficient for Pure {Datalog}}, author={Oded Shmueli}, pages={91--97}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={Datalog is a query language for relational databases. The set of predicate symbols in a Datalog program is partitioned into {\em EDB\/} (extensional database) and {\em IDB\/} (intensional database) predicates; intuitively, the EDB predicates refer to a stroed relational dabase while the IDB predicates refer to relations to be deduced from the EDB. \par We show that for each Datalor pgoram there exists a Datalog program, having at most one recursive predicate, that computes the same IDB extensions. A similar result was obtained by Chandra and Harel. However, they used the built-in predicate~$\neq$. This built-in predicate is not part of the repertoire of pure Datalog and is not used in the construction of this paper.} } @Article{HoogersKT95, refkey={C1337}, title={A Trace Semantics for {Petri} Nets}, author={P. W. Hoogers and H. C. M. Kleijn and P. S. Thiagarajan}, pages={98--114}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={A generalization of the notion of trace is proposed. This enables us to associate with each Petri net a single behavioural object, namely a poset of (generalized) traces. A characterization is given of the trace languages defined by Petri nets. We show that the general event structures of Winskel and the stable event structures can also be characterized in terms of our trace languages. One consequence is that in this framework, stable event structures, general event structures, and Petri nets constitute a strictly ascending chain in terms of expressive power.}, xxx-references={LICS::DeganoMM89, GoltzR83, NielsenRT95, Winskel87} } @Article{CastagnaGL95, refkey={C1377}, title={A Calculus for Overloaded Functions with Subtyping}, author={Giuseppe Castagna and Giorgio Ghelli and Giuseppe Longo}, pages={115--135}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We present a simple extension of typed $\lambda$-calculus where functions can be {\em overloaded\/} by putting different ``branches of code'' together. When the function is applied, the branch to execute is chosen according to a particular selection rule which depends on the type of the argument. The crucial feature of the present approach is that the branch selection depends on the ``run-time type'' of the argument, which may differ from its compile-time type, because of hte existence of a subtyping relation among types. Hence overloading cannot be eliminated by a static analysis of code, but it is an essential feature to be dealt with during computation. We obtain in this way a type-dependent calculus, which differs from the various $\lambda$-calculi where types do not play any r\^ole during computation. We prove confluence and a generalized subject-reduction theorem for this calculus. We prove strong normalization for a ``stratified'' subcalculus. The definition of this calculus is guided by the understanding of object-oriented features and the connections between our calculus and object-orientedness are extensively stressed. We show that this calculus provides a foundation for typed object-oriented languages which solves some of the prolbems of the standard record-based approach.}, xxx-references={Cardelli88, CurienG94, LICS::LongoMS93, Wand91} } @Article{BelliaO95, refkey={C1231}, title={Suprema of Open and Closed Formulas and Their Application to Resolution}, author={Marco Bellia and M. Eugenia Occhiuto}, pages={136--150}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We discuss an algebra of open formulas, SOAF\@. The algebra is equipped with the operator mgi-o, which computs suprema of sets of open formulas, ordered according to a weak form of instance ordering. Rules to compute such points are provided. These rules supply a computation procedure to unify open formulas. Next, we consider an algebra of closed formulas, SCAF\@. It has an operator mgi-c, which computes suprema of sets of formulas ordered according to the instance preordering. We give rules to compute such points. These rules supply a computation procedure to unify closure formulas. Relations between these operators and unification in open and closed formulas, and weak unification in closed formulas, are addressed. Besides, we consider clausal formulas and apply these considerations to the resolution process. This provides a rule alternative to resolution and shows that resolvents can be expressed and effectively obtained as suprema of closed formulas. The new rule need not resort to renaming, unification and instantiation as first-class operations. Finally, application so resolution in Horn clause logic and logic programming are then discussed. This leads to a more compact theory of logic programming, in which, for instance, the domain of substitutions is eliminated.}, xxx-references={JACM::Huet80, JACM::Robinson65}, full-xxx-references={TCS::BelliaO93, TCS::FalaschiLPM89, JACM::Huet80, JACM::Robinson65} } @Article{Ludwig95, refkey={C1415}, title={A Subexponential Randomized Algorithm for the Simple Stochastic Game Problem}, author={Walter Ludwig}, pages={151--155}, journal=iandcomp, month={15~} # feb, year=1995, volume=117, number=1, abstract={We describe a randomized algorithm for the simple stochastic game problem that requires $2^{O(\sqrt{n})}$ expected operations for games with $n$ vertices. This is the first subexponential time algorithm for this problem.}, xxx-references={Condon92, FOCS::Gartner92, STOC::Kalai92} } March 1995 Volume 117, Number 2 @Article{Baudinet95, refkey={C1116}, title={On the Expressiveness of Temporal Logic Programming}, author={Marianne Baudinet}, pages={157--180}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={In this paper, we address expressiveness issues for temporal logic programming, and in particular for the language {\sc templog}. We focus on the temporal component of the expressiveness by considering the propositional fragment of the language, which we call {\sc Ptemplog}. We prove that {\sc Ptemplog} is able to express positive least-fixpoint temporal properties, which (up to a convention concerning atomic formulas) corresponds to finitely regular $\omega$-languages. Finally, we consider the extension of {\sc Ptemplog} with stratified negation and we show that it is able to express all $\omega$-regular languages.}, xxx-references={JACM::AptE82, Kolaitis91, McNaughton66, Thomas79, Thomas81, JACM::EmdenK76, VardiW94, Wolper83, FOCS::WolperVS83}, full-xxx-references={SLP::AbadiM87, PODS::AbiteboulV88, POPL::AhoU79, JACM::AptE82, POPL::Baudinet89, PODS::BaudinetNW91, Kolaitis91, McNaughton66, Thomas79, Thomas81, JACM::EmdenK76, VardiW94, Wolper83, FOCS::WolperVS83} } @Article{AldousV95, refkey={C1131}, title={A {Markovian} Extension of {Valiant's} Learning Model}, author={David Aldous and Umesh Vazirani}, pages={181--186}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={An ``Occam algorithm'' learning model maintains a tentative hypothesis consistent with past observations and, when a new observation is inconsistent with the current hypothesis, updates to the next-simplest hypothesis consistent with all observations. In previous work, observations were assumed to be stochastically independent. This paper initiates the study of such models under weaker Markovian assumptions on the observations. In the special case where the sequence of hypotheses satisfying a monotonicity condition, it is shown that the number of mistakes in classifying the first $t$ observations is $O(\sqrt{t}\log(1/\pi_i))$, where $\pi_i$ is the stationary probability of the initial state, $i$, of the Markov state.}, xxx-references={STOC::BoardP90, FOCS::HausslerLW88, FOCS::LittlestoneW89} } @Article{PaturiRR95, refkey={C1147}, title={The Light Bulb Problem}, author={Ramamohan Paturi and Sanguthevar Rajasekaran and John Reif}, pages={187--192}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={In this paper, we consider the problem of correlational learning and present algorithms to determine correlated objects.}, xxx-references={STOC::Karp91, STOC::KearnsL88, FOCS::Raghavan86} } @Article{HuynhT95, refkey={C1179}, title={On Deciding Readiness and Failure Equivalences for Processes}, author={Dung T. Huynh and Lu Tian}, pages={193--205}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={In this paper, we study the complexity of deciding readiness and failure equivalences for finite state processes and recursively defined processes specified by normed context-free grammars (CFGs) in Greibach normal form (GNF). The results are as follows: (1) Readiness and failure equivalences for processes specified by normed GNF CFGs are both undecidable. For this class of processes, the regularity problem with respect to failure or readiness equivalence is also undecidable. Moreover, all these undecidability results hold even for locally unary processes. In the unary case, these problems become decidable. In fact, they are $\prod_2^p$-complete. We also show that with respect to bisimulation equivalence, the regularity for processes specified by normed GNF CFGs is {\bf NL}-complete. (2) Readiness and failure equivalences for finite state processes are {\bf PSPACE}-complete. This holds even for locally unary finite state processes. These two equivalences are co-{\bf NP}-complete for unary finite state processes. Further, for acyclic finite state processes, readiness and failure equivalences are co-{\bf NP}-complete and they are {\bf NL}-complete in the unary case. (3) For finite tree processes, we show that finite trace, readiness and failure equivalences are all {\bf L}-complete. Further, the results remain true for the unary case. Our results provide a complete characterization of the computational complexity of deciding readiness and failure equivalences for several important classes of processes.}, xxx-references={JACM::BaetenBK93, BergstraK84, JACM::BrookesHR84, Cook85, JACM::Hennessy85, KanellakisS90, FOCS::MeyerS72, STOC::StockmeyerM73} } @Article{Yokouchi95, refkey={C1303}, title={Embedding a Second Order Type System into an Intersection Type System}, author={Hirofumi Yokouchi}, pages={206--220}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={This paper presents the relationship between a second-order type assignment system $\mbox{\bf T}_{\forall}$ and an intersection type assignment system $\mbox{\bf T}_{\wedge}$. First we define a translation $\mbox{{\rm tr}}$ from intersection types to second-order types. Then we define a system $\mbox{\bf T}_{\wedge^\ast}$ obtained from $\mbox{\bf T}_{\wedge}$ by restricting the use of the intersection type introduction rule, and show that $\mbox{\bf T}_{\wedge^\ast}$ and $\mbox{\bf T}_{\forall}$ are equivalent in the following senses: (a) if a $\lambda$-term $M$ has a type $\sigma$ in $\mbox{\bf T}_{\wedge^\ast}$, then $M$ has the type $\mbox{{\rm tr}}(\sigma)$ in $\mbox{\bf T}_{\forall}$; and conversely, (b) if $M$ has a type $\tau$ in $\mbox{\bf T}_{\forall}$, then $M$ has a type $\sigma$ in $\mbox{\bf T}_{\wedge^\ast}$ such that $\mbox{{\rm tr}}(\sigma)$ is equivalent to $\tau$. These two theorems mean that $\mbox{\bf T}_{\forall}$ is embedded into $\mbox{\bf T}_{\wedge}$.}, xxx-references={JACM::FortuneLO83, LICS::GianniniR88, KfouryT92, Mitchell88} } @Article{HennessyR95, refkey={C1202}, title={A Process Algebra for Timed Systems}, author={Matthew Hennessy and Tim Regan}, pages={221--239}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={A standard process algebra is extended by a new action~$\sigma$ which is meant to denoted {\em idling\/} until the next clock cycle. A semantic theory based on testing is developed for the new language. This is characterized in terms of {\em barbs}, a variety of ready traces and also characterised as the initial theory generated by a set of equations.}, xxx-references={Abramsky91, CleavelandH90, Hennessy83, Hennessy81, NicollinS94, Schneider95}, full-xxx-references={Abramsky91, FAC::BaetenB91, CleavelandH90, TCS::NicolaH84, Hennessy83, Hennessy81, TCS::Milner83, HTCS::Milner90, NicollinS94, TCS::Phillips87, Schneider95} } @Article{Ben-DavidIK95, refkey={C1206}, title={Learning by Distances}, author={Shai Ben-David and Alon Itai and Eyal Kushilevitz}, pages={240--250}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={A model of {\em learning by distances\/} is presented. In this model a concept is a point in a metric space. At each step of the learning process the student guesses a hypothesis and receives from the teacher an approximation of its distance to the target. \par A notion of a distance, measuring the proximity of a hypothesis to the correct answer, is common to many models of learnability. By focusing on this fundamental aspect we discover some general and simple tools for the analysis of learnability tasks. \par As a corollary we present new learning algorithms for Valiant's $PAC$ scenario with any given distribution. These algorithms can learn any $PAC$--learnable class and, in some cases, settle for significantly less information than the usual labeled examples. \par Insight gained by the new model is applied to show that every class of subsets ${\cal C}$ that has a finite $VC$--dimension is $PAC$--learnable with respect to any fixed distribution. Previously known results of this nature were subject to complicated measurability constraints.}, xxx-references={Angluin87, JACM::BlumerEHW89, EhrenfeuchtHKV89, STOC::Kearns93, FOCS::LinialMN89} } @Article{BossutDW95, refkey={C1238}, title={A {Kleene} Theorem for a Class of Planar Acyclic Graphs}, author={Francis Bossut and Max Dauchet and Bruno Warin}, pages={251--265}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={In this paper, we study planar directed ordered connected acyclic graphs, in particular graphs that can be built over a (finite) doubly-ranked alphabet by parallel and serial composition. On the one hand we introduce finite automata on graphs and, on the other hand, rational expressions that involve union, nondeterministic parallel composition, serial composition, and the iterations of these compostions. We prove a Kleene Theorem linking these two characterizations of sets of graphs}, xxx-references={ArbibG68, Buttelmann75a, Buttelmann75b, Courcelle90, EilenbergW67, KamimuraS81, Loeckx70, MezeiW67, Schnorr69a} } @Article{Subramanian95, refkey={C1410}, title={The Parallel Complexity of Propagation in {Boolean} Circuits}, author={Ashok Subramanian}, pages={266--275}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={We consider the problem of deciding whether the output of a boolean circuit is determined by a partial assignment to its inputs. This problem is easily shown to be hard, i.e., {\sl co}-${\cal NP}$-complete. However, many of the consequences of a partial input assignment may be determined in linear time, by iterating the following step: if we know the values of some inputs to a gate, we can deduce the values of some outputs of that gate. This process of iteratively deducing some of the consequences of a partial assignment is called {\em propagation}. This paper explores the parallel complexity of propagation, i.e., the complexity of determining whether the output of a given boolean circuit is determined by propagating a given partial input assignment. We give a complete classification of the problem into those cases that are ${\cal P}$-complete and those that are unlikely to be ${\cal P}$-complete.}, xxx-references={Cook85} } @Article{GoldmanKS95, refkey={C1411}, title={On the Sample Complexity of Weakly Learning}, author={Sally A. Goldman and Michael J. Kearns and Robert E. Schapire}, pages={276--287}, journal=iandcomp, month=mar, year=1995, volume=117, number=2, abstract={In this paper, we study the sample complexity of weak learning. That is, we ask how much data must be collected from an unknown distribution in order to extract a small but significant advantage in prediction. We show that it is important to distinguish between those learning algorithms that output {\em deterministic hypotheses\/} and those that output {\em randomized hypotheses}. We prove that in the weak learning model, any algorithm using deterministic hypotheses to weakly learn a class of Vapnik-Chervonenkis dimension $d(n)$ requires $\Omega(\sqrt{d(n)})$ examples. In contrast, when randomized hypotheses are allowed, we show that $\Theta(1)$ examples suffice in some cases. We then show that there exists an efficient algorithm using deterministic hypotheses that weakly learns against {\em any\/} distribution on a set of size $d(n)$ with only $O(d(n)^{2/3})$ examples. Thus for the class of symmetric Boolean functions over $n$ variables, where the strong learning sample complexity is $\Theta(n)$, the sample complexity for weak learning using deterministic hypotheses is $\Omega(\sqrt{n})$ and $O(n^{2/3})$, and the sample complexity for weak learning using randomized hypotheses is $\Theta(1)$. Next we prove the existence of classes for which the distribution-free sample size required to obtain a slight advantage in prediction over random guessing is essentially equal to that required to obtain arbitrary accuracy. Finally, for a class of small circuits, namely all parity functions of subsets of $n$ Boolean variables, we prove a weak learning sample complexity of $\Theta(n)$. This bound holds even if the weak learning algorithm is allowed to replace random sampling with membership queries, and the target distribution is uniform on $\{0,1\}^n$.}, xxx-references={JACM::BlumerEHW89, Freund95, HausslerKLW91, JACM::KearnsV94, JACM::PittV88, STOC::KearnsV89} } April 1995 Volume 118, Number 1 @Article{AmirF95, refkey={C1322}, title={Efficient 2-Dimensional Approximate Matching of Half-Rectangular Figures}, author={Amihood Amir and Martin Farach}, pages={1--11}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={Efficient algorithms exist for the approximate two dimensional matching problem for rectangles. This is the problem of finding all occurrences of an $m\times m$ pattern in an $n\times n$ text with no more than $k$ mismatch, insertion, and deletion errors. In computer vision it is important to generalize this problem to non-rectangular figures. We make progress towards this goal by defining {\em half-rectangular\/} figures of height $m$ and area $a$. The approximate two dimensional matching problem for half-rectangular patterns can be solved using a dynamic programming approach in time $O(a n^2)$. We show an $O(k n^2 \sqrt{m\log{m}} \sqrt{k\log{k}} + k^2 n^2)$ algorithm which combines convolutions with dynamic programming. Note that our algorithm is superior to previous known solutions for $k\leq m^{1/3}$. \par At the heart of the algorithm are the {\em Smaller Matching Problem\/} and the {\em k-Aligned Ones with Location Problem}. These are interesting problems in their own right. Efficient algorithms to solve both these problems are presented.}, references={sicomp::AmirBF1994, sicomp::Abrahamson1987, soda::AmirF1991, algor::ApostolicoILSV1988, tcs::AmirL1991, soda::AmirLV1990, sicomp::Baker1978, jcss::GalilS1983, spaa::KedemLP1989, sicomp::KnuthMP1977, jalgo::Ukkonen1985, sicomp::Vishkin1991, STOC::IduryS1993, STOC::LandauV1986, FOCS::GalilP1992, FOCS::Weiner1973}, preliminary={soda::AmirF1991:212} } @Article{Stuckey95, refkey={C1447}, title={Negation and Constraint Logic Programming}, author={Peter J. Stuckey}, pages={12--33}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={Almost all constraint logic programming systems include negation, yet nowhere has a sound operational model for negation in CLP been discussed. The SLDNF approach of aonly allowing ground negative subgoals to execute is very restrictive in constraint logic programming where most variables appearing in a derviation never become ground. By describing a scheme for constructive negation in constraing logic programming we give a sound and complete operational model for negation in these languages. \par Constructive negation was first formulated for logic programming in the Herbrand Universe and involves introducing disequality constraints. Constraint logic programming thus provides a much more natural framework for describing constructive negation. In this paper we describe a framework for constructive negation for constraing logic prgramming over arbitrary structures which is sound and complete with respect to the three-valued consequences of the completion of a program. Through this description, we arrive at a simpler, more efficient form of constructive negation for the Herbrand Universe. Finally we characterize what makes a structure particularly suited to the use of constructive negation and show this suitability condition for a number of structures and classes of structures. \par The constraint viewpoint of constraint logic programming is well matched with constructive negation. Not only is constructive negation easier to understand from this point of view, but more importantly it gives the first clean approach to negation in constraint logic programming.}, xxx-references={LICS::Maher88} } @Article{KhullerM95, refkey={C1262}, title={A Simple Randomized Sieve Algorithm for the Closest-Pair Problem}, author={Samir Khuller and Yossi Matias}, pages={34--37}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={We present a linear time randomized sieve algorithm for the closest-pair problem. The algorithm as well as its analysis are simple. The algorithm is extended to obtain a randomized linear time approximation algorithm for the closest bichromatic pair problem.}, xxx-references={STOC::Ben-Or83, STOC::BentleyS76, FOCS::Clarkson83, JACM::FredmanKS84, FOCS::ShamosH75} } @Article{Vogler95, refkey={C1389}, title={Generalized {OM}-Bisimulation}, author={Walter Vogler}, pages={38--47}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={History preserving bisimilarity and maximality preserving bisimilarity take full account of the interplay between causality and branching, and they are congruences w.r.t.\ action refinement for suitable classes of Petri nets. But even for finite safe Petri nets they are based on possibly infinite transition systems, and it is not obvious how to decide them. $OM$-bisimulation gives a characterization of history preserving bisimulation for safe nets without internal moves, and it allows a decidability result. In this paper we generalize $OM$-bisimulation and this decidability result to safe nets with internal moves, and also treat the case of maximality preserving bisimulation.}, xxx-references={GoltzR83} } @Article{BultmanM95, refkey={C1233}, title={Fast Identification of Geometric Objects with Membership Queries}, author={William J. Bultman and Wolfgang Maass}, pages={48--64}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={We investigate the number of membership queries that are needed to identify polygons (i.e., intersections of halfplanes) over a two-dimensional grid $\{0,\ldots, n- 1\}^2$ . We exhibit a learning algorithm that learns 100\% correctly, while requiring no random examples and not more membership queries than previous algorithms needed in addition to their random examples for probably almost correctly learning (even for moderate values of $\epsilon$, $\delta$). Furthermore, the learning algorithm in this paper only uses grid points for its membership queries. This appears to be appropriate in situations where the probing device only has a limited resolution, and for applications to the set of pixels on a two-dimensional screen. \par The learning algorithm that is described in this paper overcomes a fundamental obstacle related to the zigzag borderline that is generated by a halfplane over a discrete grid. This obstacle had thwarted previous attempts to show that, in Angluin's model for on-line learning with equivalence and membership queries, one can learn in an efficient manner even those classes of geometric objects which cannot be learnt fast by equivalence queries alone (such as rectangles in general position).}, xxx-references={FOCS::AngluinFP90, Angluin87, FOCS::MaassT89, FOCS::MaassT90, JACM::PittV88} } @Article{Shawe-Taylor95, refkey={C1407}, title={Sample Sizes for Threshold Networks with Equivalences}, author={John Shawe-Taylor}, pages={65--72}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={This paper applies the theory of Probably Approximately Correct (PAC) learning to multiple ouput feedforward threshold networks in which the weights conform to certain equivalences. It is shown that the sample size for reliable learning can be bounded above by a formula similar to that required for single output networks with no equivalences. The best previously obtained bounds are improved for all cases.}, xxx-references={JACM::BlumerEHW89} } @Article{BeigelKS95a, refkey={C1366}, title={Quantifying the Amount of Verboseness}, author={Richard Beigel and Martin Kummer and Frank Stephan}, pages={73--90}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={We study the fine structure of the classification of sets of natural numbers $A$ according to the number of queries which are needed to compute the $n$-fold characteristic function of $A$. A complete characterization is obtained, relating the question to finite combinatorics. In order to obtain an explicit description we consider several interesting combinatorial problems.}, xxx-references={AmirG88, BeigelGGO93, JACM::BlumerEHW89, KummerS95} } @Article{KucherovT95, refkey={C1406}, title={Decidability of Regularity and Related Properties of Ground Normal Form Languages}, author={Gregory Kucherov and Mohamed Tajine}, pages={91--100}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={We study language-theoretical properties of the set of reducible ground terms and its complement - the set of ground normal forms induced by a given rewriting system. As a tool for our analysis we introduce the property of finite irreducibility of a term with respect to a variable and prove it to be decidable. It turns out that this property generalizes numerous interesting properties of the language of ground normal forms. In particular, we show that testing regularity of this language can be reduced to verifying this property. In this way we prove the decidability of the regularity of the set of ground normal forms, the problem mentioned in the list of open problems in rewriting (Dershowitz, Jouannaud, and Klop, 1991). Also, the decidability of the existence of an equivalent ground term rewriting system and some other results are proved.}, xxx-references={Plaisted85} } @Article{TouatiBK95, refkey={C1285}, title={Testing Language Containment for {$\omega$}-Automata Using {BDD}'s}, author={Herv{\'e} J. Touati and Robert K. Brayton and Robert Kurshan}, pages={101--109}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={$\omega$-automata provide a well-established basis for the specification and verification of control-intensive systems. To verify that a system satisfies a given property (``task''), one specifies both the system and the task in terms of $\omega$-automata, and then verifies that the $\omega$-regular language of the system automaton is contained in that of the task automaton. This procedure, which is the basis of the COSPAN verification software, has been used in a number of commercial applications. However, its applicability is limited by the computational complexity of the ensuing language containment check, which tends to grow exponentially with the number of components in the system. While reduction techniques such as task decomposition and task-relative homomorphic reduction can greatly extend the complexity of systems which thus may be analyzed, there is a computational cost associated with such reductions as well. Moreover, the system complexity ultimately is the limiting factor. Recent advances in the manipulation of data-structures for binary decision diagrams (BDD's) have suggested that this data-structure may now facilitate checking language containment for far larger system models than has been hitherto possible. We have confirmed this by implementing new BDD-based language containment checks in COSPAN. We exhibit two such algorithms: one with a time advantage and the other with a space advantage. Each has increased significantly the size of system models which can be verified.}, xxx-references={LICS::BurchCMDH90, LICS::EmersonL86}, full-xxx-references={IEEETC::Akers78, DAC::BraceBR90, IEEETC::Bryant86, IEEETC::Bryant91, LICS::BurchCMDH90, JCSS::Choueka74, TOPLAS::ClarkeES86, MISC::CoudertBM89, HTCS::Emerson90, LICS::EmersonL86, MISC::GareyJ79, MISC::HarelK90, MISC::HojatiTKB92, MISC::JeongPHS91, TCS::Kozen83, MISC::Kurshan87, MISC:;Kurshan90, MISC::Kurshan93, BSTJ::Lee59, ICCAD::SrinivasanKMB90, MISC::TouatiBK91, ICCAD::TouatiSLBS-V90} } @Article{LitovskyMZ95, refkey={C1288}, title={On the Recognition of Families of Graphs with Local Computations}, author={Igor Litovsky and Yves M{\'e}tivier and Wies{\l}aw Zielonka}, pages={110--119}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={This paper is a contribution to understanding the power and the limitations of local computations in graphs. We use local computations to define a notion of graph recognition; our model enables a simulation of automata on words and on trees. We introduce the notion of $k$-covering to examine limitations of such systems. For example we prove that the family of series parallel graphs and the family of planar graphs cannot be recognized by means of local computations.}, xxx-references={STOC::Angluin80} } @Article{Takahashi95, refkey={C1352}, title={Parallel Reductions in {$\lambda$}-Calculus}, author={Masako Takahashi}, pages={120--127}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={The notion of parallel reduction is extracted from the simple proof of the Church-Rosser theorem by Tait and Martin-L\"of. Intuitively this means to reduce a number of redexes (existing in a $\lambda$-term) simultaneously. Thus in the case of $\beta$-reduction the effect of a parallel reduction is same as that of a ``complete development'' which is defined by using ``residuals'' of $\beta$-redexes. A nice feature of parallel reduction however is that it can be defined directly by induction on the structure of $\lambda$-terms (without referring to residuals or other auxiliary notions), and the inductive definition provides us exactly what we need in proving the theorem inductively. Moreover the notion can be easily extended to other reduction systems such as Girard's second-order system {\bf F} and G\"odel's system {\bf T}. \par In this paper, after reevaluating the significance of the notion of parallel reduction in Tait-and-Martin-L\"of type proofs of the Church-Rosser theorems, we show that the notion of parallel reduction is also useful in giving short and direct proofs of some other fundamental theorems in reduction theory of $\lambda$-calculus; among others, we give such simple proofs of the standardization theorem for $\beta$-reduction (a special case of which is known as the leftmost reduction theorem for $\beta$-reduction), the quasi-leftmost reduction theorem for $\beta$-reduction, the postponement theorem of $\eta$-reduction (in $\beta\eta$-reduction), and the leftmost reduction theorem for $\beta\eta$-reduction.} } @Article{PalsbergS95, refkey={C1340}, title={Safety Analysis versus Type Inference}, author={Jens Palsberg and Michael I. Schwartzbach}, pages={128--141}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={Safety analysis is an algorithm for determining if a term in an untyped lambda calculus with constants is {\em safe}, i.e., if it does not cause an error during evaluation. This ambition is also shared by algorithms for type inference. Safety analysis and type inference are based on rather different perspectives, however. Safety analysis is {\em global\/} in that it can only analyze a complete program. In contrast, type inference is {\em local\/} in that it can analyze pieces of a program in isolation. \par In this paper we prove that safety analysis is {\em sound\/}, relative to both a strict and a lazy operational semantics. We also prove that safety analysis accepts strictly more safe lambda terms than does type inference for simple types. The latter result demonstrates that global program analyses can be more precise than local ones.}, xxx-references={LICS::Despeyroux86, FOCS::KozenPS1992} } @Article{AlurIKY95, refkey={C1453}, title={Timing Verification by Successive Approximation}, author={R. Alur and A. Itai and R. P. Kurshan and M. Yannakakis}, pages={142--157}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={We present an algorithm for verifying that a model $M$ with timing constraints satisfies a given temporal property $T$. The model $M$ is given as a parallel composition of $\omega$-automata $P_i$, where each automaton $P_i$ is constrained by bounds on delays. The property $T$ is given as an $\omega$-automaton as well, and the verification problem is posed as a language inclusion question ${\cal L} (M)\subseteq {\cal L} (T)$. In constructing the composition $M$ of the constrained automata $P_i$, one needs to rule out the behaviors that are inconsistent with the delay bounds, and this step is (provably) computationally expensive. We propose an iterative solution which involves generating successive approximations $M_j$ to $M$, with containment ${\cal L}(M)\subseteq {\cal L}(M_j)$ and monotone convergence ${\cal L}(M_j) \rightarrow {\cal L}(M)$ within a bounded number of steps. As the succession progresses, the approximations $M_j$ become more complex. At any step of the iteration one may get a proof or a counter-example to the original language inclusion question. The described algorithm is implemented into the verifier Cospan. We illustrate the benefits of our strategy through some examples.}, xxx-references={AlurCD93, FOCS::AlurH89, JACM::AlurH94, LICS::HenzingerNSY92, HenzingerNSY94, LICS::Lewis90, LICS::VardiW86} } @Article{CristianASD95, refkey={C1192}, title={Atomic Broadcast: From Simple Message Diffusion to {Byzantine} Agreement}, author={Flaviu Cristian and Houtan Aghili and Ray Strong and Danny Dolev}, pages={158--179}, journal=iandcomp, month=apr, year=1995, volume=118, number=1, abstract={In distributed systems subject to random communication delays and component failures, atomic broadcast can be used to implement the abstraction of synchronous replicated storage, a distributed storage that displays the same contents at every correct processor as of any clock time. This paper presents a systematic derivation of a family of atomic broadcast protocols that are tolerant of increasingly general failure classes: omission failures, timing failures, and authentication-detectable Byzantine failures. The protocols work for arbitrary point-to-point network topologies, and can tolerate any number of link and process failures up to network partitioning. After proving their correctness, we also prove two lower bounds that show that the protocols provide in many cases the best possible termination times.}, xxx-references={STOC::AttiyaDLS91} } May 1, 1995 Volume 118, Number 2 @Article{Adamek95, refkey={C1379; PN2399}, title={Recursive Data Types in Algebraically {$\omega$}-Complete Categories}, author={Ji{\v{r}}{\'\i} Ad{\`a}mek}, pages={181--190}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={A category $\underline{K}$ (of data types) is called algebraically $\omega$-complete provided that for each endofunctor~$T$ the data-type equation $T(X) \cong X$ has a solution constructed as a colimit of the $\omega$-chain $\bot \rightarrow T(\bot) \rightarrow T^2(\bot) \ldots$, where $\bot$ is the initial data-type. Examples include the categories of 1)~countable sets and (total, partial, or nondeterministic) functions, 2)~countably dimensional vector spaces and linear functions, 3)~countable well-ordered sets and join-preserving functions. In the case of categories enriched over CPO (the category of complete partial orders and strict, continuous functions) a stronger property holds for all locally continuous functors~$T$: the data-type equation is both a limit and a colimit of the finite iterations of~$T$ over the initial data-type.}, xxx-references={ArbibM82}, full-xxx-references={ArbibM82, TCS::Wand79} } @Article{NielsenRT95, refkey={C1280; PN2423}, title={Transition Systems, Event Structures and Unfoldings}, author={M. Nielsen and G. Rozenberg and P. S. Thiagarajan}, pages={191--207}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={A subclass of Transition Systems called elementary transition systems can be identified with the help of axioms based on a structural notion called regions. Elementary transition systems have been shown to be {\em the\/} transition system model of a basic system model of net theory called elementary net systems (Nielsen et.al (1992)). Here we show that by smoothly strengthening the regional axioms for elementary transition systems, one obtains a subclass called occurrence transition system. We then prove that occurrence transition systems are {\em the\/} transition system model of yet another basic model of concurrency, namely, prime event structures. We then propose an operation of unfolding elementary transition systems into occurrence transition systems. We prove that it is ``correct'' in a strong categorical sense.}, full-xxx-references={TCS::NielsenPW81, TCS::NielsenRT92, TCS::RozoyT91} } @Article{FreivaldsKW95, refkey={C1390; PN2424}, title={How Inductive Inference Strategies Discover Their Errors}, author={R\={u}si\c{n}\v{s} Freivalds and Efim B. Kinber and Rolf Wiehagen}, pages={208--226}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={Several well-known inductive inference strategies change the actual hypothesis only when they discover that it ``provably misclassifies'' an example seen so far. This notion is made mathematically precise and its general power is characterized. In spite of its strength it is shown that this approach is not of universal power. Consequently, then hypotheses are considered which ``unprobably misclassifies'' examples and the properties of this approach are studied. Among others it turns out that universal power can be achieved only when an unbounded number of alternations of these dual types of hypotheses is allowed. Finally, a universal method is presented enabling an inductive inference strategy to verify the incorrectness of any of its incorrect intermediate hypotheses.}, xxx-references={Angluin80, BlumB75, Fulk88, FOCS::Fulk90, Gold67}, full-xxx-references={Angluin80, BlumB75, TCS::CaseS83, Fulk88, FOCS::Fulk90, Gold67} } @Article{NiedermeierR95, refkey={C1362; PN2422}, title={Unambiguous Auxiliary Pushdown Automata and Semi-unbounded Fan-in Circuits}, author={Rolf Niedermeier and Peter Rossmanith}, pages={227--245}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={Notions of unambiguity for uniform circuits and AuxPDAs are studied and related to each other. In particular, a coincidence for counting and unambiguous versions of AuxPDAs and semi-unbounded fan-in circuits is shown. Moreover, an improved simulation of LOGUCFL (the class of languages logspace many-one reducible to unambiguous context-free languages) by unambiguous circuits and AuxPDAs is developed. Next, an inductive counting technique on semi-unbounded fan-in circuits is presented and employed for several applications, especially an alternative proof for the closure under complementation of LOGCFL\@. A cost-free simulation of polynomially ambiguity bounded AuxPDAs by unambiguous ones is given. A first nontrivial upper bound for a circuit class defined by Lange and its closure under complementation are indicated. Finally, a normal form for AuxPDAs is investigated. Inter alia it is shown that for unambiguous AuxPDAs operating in polynomial time and logarithmic space a push-down height of $O(\log^2 n)$ suffices, thus paralleling results for deterministic and nondeterministic AuxPDAs. It is pointed out that without loss of generality the underlying machines of the most important AuxPDA classes work obliviously.}, xxx-references={BuntrockHS93, JACM::ChandraKS81, JACM::Cook71, STOC::Cook79, STOC::FortuneW78, STOC::Goldschlager78, JACM::Goldschlager82, Kasami67, FOCS::Pippenger79b, Rytter87, JACM::Sudborough78}, full-xxx-references={TCS::AlvarezJ93, BuntrockHS93, JACM::ChandraKS81, JACM::Cook71, STOC::Cook79, STOC::FortuneW78, STOC::Goldschlager78, JACM::Goldschlager82, TCS::HartmanisY84, Kasami67, TCS::Lange93, FOCS::Pippenger79b, Rytter87, JACM::Sudborough78} } @Article{HalpernW95, refkey={C1375; PN2382}, title={Full Abstraction and Expressive Completeness for {FP}}, author={Joseph Y. Halpern and Edward L. Wimmers}, pages={246--271}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={We consider issues related to the expressive power of the programming language FP. In particular, we consider whether a number of variants of FP are fully abstract and expressively complete. For example, we show that a version of FP with only one-sided sequences behave similarly to PCF in that the addition of parallel {\em or\/} is sufficient to make it fully abstract. \par However, the addition of parallel {\em or\/} to FP (with its two-sided infinite sequences) is {\em not\/} sufficient to achieve full abstraction. By considering these and other variants, we obtain a better understanding of what is required of a language and semantics in order to guarantee full abstraction and expressive completeness.}, xxx-references={Gunter87, JACM::HalpernWW90} } @Article{GorrieriL95, refkey={C1395; PN2393}, title={Split and {ST} Bisimulation Semantics}, author={Roberto Gorrieri and Cosimo Laneve}, pages={272--288}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={In this paper the notion of action atomicity is relaxed by permitting actions to be observed in the middle of their evolution. Non atomic semantic equivalences, based on the notion of bisimulation, are studied over stable event structures. {\tt Split}$_{n}$ bisimulation equivalence (denoted $\stackrel{n}{\sim}$) considers each event as composed of $n$ phases. {\tt ST} bisimulation equivalence (denoted $\stackrel{ST}{\sim}$) is a slight refinement of $\stackrel{2}{\sim}$ where each ending phase is unambiguously associated to a beginning phase. We prove that, by increasing $n$, we get finer and finer equivalences (i.e.\ $\stackrel{n+1}{\sim} \subseteq \stackrel{n}{\sim}$) and, moreover, that $\stackrel{n+1}{\sim}$ coincides with $\stackrel{ST}{\sim}$ over those event structures whose autoconcurrency is at most $n$. The main consequence of these results is that, for image finite event structures, $\stackrel{ST}{\sim}$ is the intersection of all the $\stackrel{n}{\sim}$.}, xxx-references={JACM::HennessyM85} } @Article{StraubingTT95, refkey={C1448; PN2425}, title={Regular Languages Defined with Generalized Quanifiers}, author={Howard Straubing and Denis Th{\'e}rien and Wolfgang Thomas}, pages={289--301}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={We study an extension of first-order logic obtained by adjoining quantifiers that count with respect to an integer modulus. It is shown that the languages definable in this framework are precisely the regular languages whose syntactic monoids contain only solvable groups. We obtain an analogous result for regular $\omega$-languages and establish some connections with complexity theory for fixed-depth families of circuits. An earlier version of this paper appeared in the Proceedings of the 1988 International Colloquium on Automata, Languages and Programming.}, xxx-references={JACM::BarringtonT88, FOCS::HajnalMPST87, Ladner77, Schutzenberger65a, Thomas79, Wolper83} } @Article{HromkovicMSV95, refkey={C1290; PN2421}, title={On Embeddings in Cycles}, author={Juraj Hromkovi{\v{c}} and Vladim{\'\i}r M{\"u}ller and Ondrej S{\'y}kora and Imrich Vr{\v{t}}o}, pages={302--305}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={We prove exact results on dilations in cycles for important parallel computer interconnection networks as complete trees, hypercubes and 2- and 3-dimensional meshes. Moreover we show that trees, $X$-trees, $n$-dimensional meshes, pyramids and trees of meshes have the same dilations both in the plane and in the cycle.} } @Article{CaucalHT95, refkey={C1394; PN2426}, title={Deciding Branching Bimiliarity of Normed Context-Free Processes Is in {$\Sigma^{\rm p}_2$}}, author={Didier Caucal and Dung T. Huynh and Lu Tian}, pages={306--315}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={We show that the problem of deciding branching bisimulation equivalence for normed context-free processes is in ${\bf \Sigma^p_2}$, the second level of the polynomial-time hierarchy, and hence in {\bf PSPACE}. We also show that minimization of normed context-free process graphs is in {\bf PSPACE}.}, xxx-references={JACM::BaetenBK93, LICS::HuttelS91, KanellakisS90} } @Article{MalerP95, refkey={C1440; PN2429}, title={On the Learnability of Infinitary Regular Sets}, author={Oded Maler and Amir Pnueli}, pages={316--326}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={In this paper we extend the automaton synthesis paradigm to infinitary languages, that is, to subsets of the set~$\Sigma^\omega$ of all infinite sequences over some alphabet~$\Sigma$. Our main result is a polynomial algorithm for learning a sub-class of the $\omega$-regular sets from membership queries and counter-examples based on the framework suggested by Angluin (Angluin, D., 1987, {\em Information and Computation\/} 75) for learning regular subsets of~$\Sigma^*$.}, xxx-references={Angluin78, Angluin81, Angluin87, JACM::BlumerEHW89, Gold67, Gold78, McNaughton66, FOCS::Muller63, JACM::PittW93, FOCS::RivestS87, Wagner79}, full-xxx-references={Angluin78, Angluin81, Angluin87, TCS::Arnold85, JACM::BlumerEHW89, Gold67, Gold78, TCS::Kaminski85, TCS::MannaP91, McNaughton66, FOCS::Muller63, JACM::PittW93, FOCS::RivestS87, Wagner79} } @Article{WeberK95, refkey={C1502; PN2428}, title={Economy of Description for Single-Valued Transducers}, author={Andreas Weber and Reinhard Klemm}, pages={327--340}, journal=iandcomp, month={1~} # may, year=1995, volume=118, number=2, abstract={In this article questions of economy of description are investigated in connection with single-valued finite transducers. The following results are shown. (1) Any single-valued real-time transducer $M$ with $n$ states can be effectively transformed into an equivalent unambiguous real-time transducer having at most $2^n$ states. (2) Let $M$ be a single-valued real-time transducer with $n$ states and output alphabet $\Delta$ which is equivalent to some deterministic real-time or subsequential transducer $M'$. Then, $M$ can be effectively transformed into such an $M'$ having at most $1 + 2^n \cdot \max \{ 2 , \# \Delta \}^{2 n^3 l}$ states where $l$ is a local structural parameter of $M$. (3) For any single-valued real-time transducer $M$ it is decidable in deterministic polynomial time whether or not it is equivalent to some deterministic real-time transducer (to some subsequential transducer, respectively). The results (1)--(3) can be extended to the case where $M$ is not necessarily real time. The upper bound in (1) is at most one state off the optimal upper bound. Any possible improvement of the upper bound in (2) is greater than or equal to $2^n - 1$.}, xxx-references={FOCS::MeyerF71} } May 15, 1995 Volume 119, Number 1 @Article{SeberryZZ95, refkey={C1491}, title={Nonlinearity and Propagation Characteristics of Balanced {Boolean} Functions}, author={Jennifer Seberry and Xian-Mo Zhang and Yuliang Zheng}, pages={1--13}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={Three important criteria for cryptographically strong Boolean functions are balance, nonlinearity and the propagation criterion. The main contribution of this paper is to reveal a number of interesting properties of balance and nonlinearity, and to study systematic methods for constructing Boolean functions that satisfy some or all of the three criteria. We show that concatenating, splitting, modifying and multiplying (in the sense of Kronecker) sequences can yield balanced Boolean functions with a very high nonlinearity. In particular, we show that balanced Boolean functions obtained by modifying and multiplying sequences achieve a nonlinearity higher than that attainable by any previously known construction method. We also present methods for constructing balanced Boolean functions that are highly nonlinear and satisfy the strict avalanche criterion (SAC)\@. Furthermore we present methods for constructing highly nonlinear balanced Boolean functions satisfying the propagation criterion with respect to {\em all but one or three\/} vectors. A technique is developed to transform the vectors where the propagation criterion is not satisfied in such a way that the functions constructed satisfy the propagation criterion of high degree while preserving the balance and nonlinearity of the functions. The algebraic degrees of functions constructed are also discussed.} } @Article{Dekkers95, refkey={C1230}, title={Inhabitation of Types in the Simply Typed Lambda Calculus}, author={Wil Dekkers}, pages={14--17}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={In the sixties mathematicians from Eastern Europe showed that every admissable rule in the intuitionistic implicational calculus is derivable. We shall prove the corresponding proposition for the simply typed lambda calculus: The type $\mu_1 \to \mu_2 \to \cdots \to \mu_m \to \nu$ is inhabited iff for each substitution~$s$ of types for the variables in $\mu_1, \dots, \mu_m, \nu$ the inhabitation of $s(\mu_1), \dots, s(\mu_m)$ implies the inhabitation of~$\nu$.} } @Article{KennawayKSV95, refkey={C1323}, title={Transfinite Reductions in Orthogonal Term Rewriting Systems}, author={Richard Kennaway and Jan Willem Klop and Ronan Sleep and Fer-Jan de Vries}, pages={18--38}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={We define the notion of transfinite term rewriting: rewriting in which terms may be infinitely large and rewrite sequences may be of any ordinal length. For orthogonal rewrite systems, some fundamental properties known in the finite case are extended to the transfinite case. Among these are the Parallel Moves lemma and the Unique Normal Form property. The transfinite Church-Rosser property (CR$^\infty$) fails in general, even for orthogonal systems, including such well-known systems as Combinatory Logic. Syntactic characterisations are given of some classes of orthogonal TRSs which do satisfy CR$^\infty$. We also prove a weakening of CR$^\infty$ for all orthogonal systems, in which the property is only required to hold up to a certain equivalence relation on terms. Finally, we extend the theory of needed reduction from the finite to the transfinite case. The reduction strategy of needed reduction is normalising in the finite case, but not in the transfinite case. To obtain a normalising strategy, it is necessary and sufficient to add a requirement of fairness. Parallel outermost reduction is such a strategy.}, xxx-references={TOPLAS::KennawayKSV94, JACM::Rosen73}, } @Article{Yamanishi95, refkey={C1277}, title={A Loss Bound Model for On-Line Stochastic Prediction Algorithms}, author={Kenji Yamanishi}, pages={39--54}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={In this paper we consider the problem of on-line prediction in which at each time an unlabeled instance is given and then a prediction algorithm outputs a probability distribution over the set of labels rather than $\{0, 1\}$-values before it sees the correct label. For this setting, we propose a weighted-average-type on-line stochastic prediction algorithm $WA$, which can be regarded as a hybrid of the Bayes algorithm and a sequential real-valued parameter estimation method. We derive upper bound on the instantaneous logarithmic loss and cumulative logarithmic loss for $WA$ in both the example-dependent form and the expected form (the expectation is taken with respect to the fixed target distribution of sequences). Specifically, under some specific parametric assumptions for target rules, we prove that $WA$ is optimal in the sense that an upper bound on the expected cumulative logarithmic loss for $WA$ asymptotically matches Rissanen's coding-theoretic lower bound. Further we derive an upper bound on the expected cumulative quadratic loss by making use of relationships between the quadratic loss and logarithmic loss. Throughout the paper we relate computational learning theory to information theory, most specifically, Rissanen's predictive minimum description length principle, by giving noiseless coding theoretic interpretations to the loss bounds.}, xxx-references={Haussler92, FOCS::KearnsS90, FOCS::LittlestoneW89, Vovk92} } @Article{HonsellMST95, refkey={C1429}, title={A Variable Typed Logic of Effects}, author={Furio Honsell and Ian A. Mason and Scott Smith and Carolyn Talcott}, pages={55--90}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={In this paper we introduce a variable typed logic of effects inspired by the variable type systems of Feferman for purely functional languages. VTLoE (Variable Typed Logic of Effects) is introduced in two stages. The first stage is the first-order theory of individuals built on assertions of equality (operational equivalence \`a la Plotkin), and contextual assertions. The second stage extends the logic to include classes and class membership. The logic we present provides an expressive language for defining and studying properties of programs including program equivalences, in a uniform framework. The logic combines the features and benefits of equational calculi as well as program and specification logics. In addition to the usual first-order formula constructions, we add {\em contextual assertions}. Contextual assertions generalize Hoare's triples in that they can be nested, used as assumptions, and their free variables may be quantified. They are similar in spirit to program modalities in dynamic logic. We use the logic to establish the validity of the Meyer Sieber examples in an operational setting. The theory allows for the construction of inductively defined sets and derivation of the corresponding induction principles. We hope that classes may serve as a starting point for studying semantic notions of type. Na{\"\i}ve attempts to represent ML types as classes fail in sense that ML inference rules are not valid.}, xxx-references={POPL::CrankF91, Bloom90, GermanCH89, POPL::HalpernMT84, LICS::Howe89, POPL::JouvelotG91, POPL::LeroyW91, POPL::LucassenG88, LICS::Mason86, LICS::MasonT89, LICS::MasonT92, POPL::MeyerS88, LICS::Moggi89, Moggi91, POPL::OHearnT93, OHearnT93, POPL::Reynolds78, Tofte90, POPL::WeeksF93}, full-xxx-references={Bloom90, TCS::FelleisenF89, TCS::FelleisenH92, GermanCH89, LICS::Howe89, LICS::Mason86, LICS::MasonT89, TCS::MasonT92, LICS::MasonT92, TCS::Milner77, LICS::Moggi89, Moggi91, OHearnT93, TCS::Plotkin75, TCS::Talcott91, TCS::Talcott93, Tofte90} } @Article{LodayaPRT95, refkey={C1358}, title={A Logical Study of Distributed Transition Systems}, author={Kamal Lodaya and Rohit Parikh and R. Ramanujan and P. S. Thiagarajan}, pages={91--118}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={We extend labelled transition systems to {\em distributed transition systems\/} by labelling the transition relation with a finite set of actions, representing the fact that the actions occur as a {\em concurrent step}. We design an action-based temporal logic in which one can explicitly talk about steps. The logic is studied to establish a variety of positive and negative results in terms of axiomatizability and decidability. \par Our positive results show that the step notion is amenable to logical treatment via standard techniques. They also help us to obtain a logical characterization of two well known models for distributed systems: labelled elementary net systems and labelled prime event structures. \par Our negative results show that demanding deterministic structures when dealing with a ``non-interleaved'' notion of transitions is, from a logical standpoint, very expressive. They also show that another well known model of distributed systems called asynchronous transition systems exhibits a surprising amount of expressive power in a natural logical setting.}, xxx-references={JACM::HennessyM85, FOCS::Pnueli77} } @Article{BergstraH95, refkey={C1505}, title={Homomorphism Preserving Algebraic Specifications Require Hidden Sorts}, author={J. A. Bergstra and Jan Heering}, pages={119--123}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={Although every computable data type has an initial algebra specification with hidden functions, it may happen that some of the homomorphic images of the data type are not models of the specification. The latter are reducts of algebras that would be models of the specification if all its functions were visible, whereas the homomorphic images of the data type are independent of the specification and need not be compatible with the hidden functions used in it. A hidden function specification that does not exclude any of the homomorphic images of its initial model from its model class will be called {\em homomorphism preserving}. It turns out that, unlike unrestricted initial algebra specification, homomorphism preserving initial algebra specification of computable data types requires both hidden sorts and hidden functions.}, xxx-references={JACM::BergstraHK90, BergstraK84, BergstraT82} } @Article{Hagerup95, refkey={C1103}, title={A Lower Bound for the Emulation of {PRAM} Memories on Processor Networks}, author={Torben Hagerup}, pages={124--128}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={We show a lower bound of $\Omega(\min\{\log m, \sqrt{n}\})$ on the slowdown of any deterministic emulation of a PRAM memory with $m$ cells and $n$ I/O ports on an $n$-processor bounded-degree network. The bound is weak; unlike all previous bounds, however, it does not depend on the unnatural assumption of point-to-point communication which says, roughly, that messages in transit cannot be duplicated by intermediate processors. For $m$ sufficiently large relative to~$n$, the new bound implies the optimality of a simple emulation on a mesh-of-trees network.}, references={SICOMP::AltHMP1987, ACCCC::HerleyB1988, JACM::KarlinU1988:876, SICOMP::PelegU1989:229, JACM::Rabin1989:335, JCSS::Ranade1991} } @Article{GradelM95, refkey={C1405}, title={On the Power of Deterministic Transitive Closures}, author={Erich Gr{\"a}del and Gregory L. McColm}, pages={129--135}, journal=iandcomp, month={15~} # may, year=1995, volume=119, number=1, abstract={We show that transitive closure logic {\rm (FO + TC)} is strictly more powerful than deterministic transitive closure logic {\rm (FO + DTC)} on finite (unordered) structures. In fact, on certain classes of graphs, such as hypercubes or regular graphs of large degree and girth, every DTC-query is bounded and therefore first order expressible. On the other hand there are simple {\rm (FO + pos TC)} queries on these classes that cannot be defined by first order formulae.}, xxx-references={FOCS::GradelM92} } June 1995 Volume 119, Number 2 @Article{FerrucciPS95, refkey={C1371}, title={Redundancy Elimination and Loop Checks for Logic Programs}, author={F. Ferrucci and G. Pacini and Maria I. Sessa}, pages={137--153}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={A simple analysis of the arguments developed in [Bot {\em et al}. (1991)] shows that an actual reason for the non existence of a complete sound simple loop check for all function-free programs is the presence in the resolvements of potentially unlimited sequences of atoms chained by common variables. This hints that a limitation of the number of variables generating this kind of chains could work in order to guarantee the applicability of complete simple loop checks. This line is followed in the paper, and quite general classes of logic programs are characterized, without any direct imposition on the structure of the rules. This objective is accomplished exploiting a variant of the SLD-resolution, which is able to perform a systematic elimination of redundant atoms from resolvents. As a notable result, it turns out that the equality loop check is complete for our class of logic programs. This seems to suggest that the necessity of using subsumption loop checks instead of equality checks is essentially due to the presence of redundant atoms in resolvents.}, xxx-references={JACM::Joyner76} } @Article{NakayamaM95, refkey={C1472}, title={Loop Circuits and Their Relation to {Razborov's} Approximation Model}, author={Katsutoshi Nakayama and Akira Maruoka}, pages={154--159}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={Recently a new technique called the method of approximations has been developed for proving lower bounds on the size of circuits computing certain Boolean functions. To obtain a lower bound on the size complexity $size(f)$ of a certain function $f$ by the method, an appropriate legitimate model $\cal M$ for the function $f$ is chosen, and then a lower bound on the distance $\rho(f, {\cal M})$ from $f$ to $\cal M$ is derived. The lower bound on $\rho(f, {\cal M})$ becomes a lower bound on $size(f)$ in view of the fact that $size(f) \geq \rho(f, {\cal M})$. Razborov gave a legitimate monotone model, ${\cal M}_{\it mon}({\cal F}_{\max})$ and showed that $\rho(f, {\cal M}_{\it mon}({\cal F}_{\max})) = \Omega(size^{1/3}(f))$, so there remains a gap between the size $size(f)$ and the distance $\rho(f, {\cal M})$. Employing his method, the following statements are established: (i)~the Razborov's model ${\cal M}_{\it mon}({\cal F}_{\max})$ is generalized to obtain model ${\cal M}({\cal F}_{\max})$ and it is established that $\rho(f, {\cal M}({\cal F}_{\max})) = \Omega (size^{1/2}(f))$; (ii)~Allowing the underlying graphs of circuits to have cycles, a new notion of apparently more powerful circuits, called loop circuits, is introduced and it is proved that $\rho(f, {\cal M}({\cal F}_{\max})) = \Theta(size_{loop}(f))$, where $size_{loop}(f)$ denotes the size complexity of $f$ based on loop circuits.}, xxx-references={STOC::Razborov89} } @Article{DawarLW95, refkey={C1361}, title={Infinitary Logic and Inductive Definability over Finite Structures}, author={Anuj Dawar and Steven Lindell and Scott Weinstein}, pages={160--175}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={The extensions of first-order logic with a least fixed point operator (FO + LFP) and with a partial fixed point operator (FO + PFP) are known to capture the complexity classes P and PSPACE respectively in the presence of an ordering relation over finite structures. Recently, Abiteboul and Vianu [Abiteboul and Vianu, 1991b] investigated the relationship of these two logics in the absence of an ordering, using a machine model of generic computation. In particular, they showed that the two languages have equivalent expressive power if and only if P = PSPACE. These languages can also be seen as fragments of an infinitary logic where each formula has a bounded number of variables, $L^\omega_{\inf\omega}$ (see, for instance, [Kolaitis and Vardi, 1990]). We investigate this logic of finite structures and provide a normal form for it. We also present a treatment of the results in [Abiteboul and Vianu, 1991b] from this point of view. In particular, we show that we can write a formula of FO + LFP that defines an ordering of the $L^k_{\inf\omega}$ types uniformly over all finite structures. One consequence of this is a generalization of the equivalence of FO + LFP and P from ordered structures to classes of structures where every element is definable. We also settle a conjecture mentioned in [Abiteboul and Vianu, 1991b] by showing that FO + LFP is properly contained in the polynomial time computable fragment of $L^\omega_{\inf\omega}$, raising the question of whether the latter fragment is a recursively enumerable class.}, xxx-references={STOC::AbiteboulV91, BlassGK85, FOCS::CaiFI89, Immerman86, LICS::KolaitisV90, LICS::KolaitisV92, KolaitisV92, STOC::Vardi82} } @Article{Cosmo95, refkey={C1209}, title={Second Order Isomorphic Types: A Proof Theoretic Study on Second Order {$\lambda$}-Calculus with Surjective Paring and Terminal Object}, author={Roberto Di Cosmo}, pages={176--201}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={We investigate invertible terms and isomorphic types in the second order lambda calculus extended with surjective pairs and terminal (or {\em Unit\/}) type. These two topics are closely related: on one side, the study of invertibility is a necessary tool for the characterization of isomorphic types; on the other hand, we need the notion of isomorphic types to study the typed invertible terms. The result of our investigation is twofold: we give a constructive characterization of the invertible terms, extending previous work by Dezani and Bruce-Longo [Dez76, BL85], and a decidable equational theory of the isomorphisms of types which hold in all models of the calculus, which is a conservative extension to the second order case of the results previously achieved for the case of first order typed calculi. Via the Curry-Howard correspondence, this work also provides a decision procedure for {\em strong equivalence\/} of formulae in second order intuitionistic positive propositional logic, that is suitable to search equivalent proofs in automated deduction systems.}, xxx-references={STOC::BruceL85} } @Article{BarbaneraDL95, refkey={C1432}, title={Intersection and Union Types: Syntax and Semantics}, author={Franco Barbanera and Mariangiola Dezani-Ciancaglini and Ugo de'Liguoro}, pages={202--230}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={Type assignment systems with intersection and union types are introduced. Altough the subject reduction property with respect to $\beta$-reduction does not hold for a natural deduction-like system, we manage to overcome this problem in two different ways. The first is to adopt a notion of papallel reduction, which is a refinement of Gross-Knuth reduction. The second is to introduce type theories to refine the system, among which the theory called $\Pi$ that induces an assignment system preserving $\beta$-reduction. This type assignment system further clarifies the relation with the intersection discipline through the decomposition of, first, a disjunctive type into a set of conjunctive types and, second, of a derivation in the new type assignment system into a set of derivations in the intersection type assignment system. For this system we propose three semantics and prove soundness and completeness theorems.}, xxx-references={Boudol94, MacQueenPS86, Meyer82, LICS::Ong93} } @Article{ChenT95, refkey={C1514}, title={The Complexity of Selecting Maximal Solutions}, author={Zhi-Zhong Chen and Seinosuke Toda}, pages={231--239}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={Many important computational problems involve finding a maximal (with respect to set inclusion) solution in some combinatorial context. We study such maximality problems from the complexity point of view, and categorize their complexity precisely in terms of tight upper and lower bounds. Our results give characterizations of coNP, D$^{\rm P}$, $\Pi^{\rm P}_2$, FP$^{\rm NP}_{\parallel}$, FNP/\hspace{-1mm}/OptP$[\log n]$ and FP$^{\Sigma^{\rm P}_2}_{\parallel}$ in terms of subclasses of maximality problems. An important consequence of our results is that finding an $X$-minimal satisfying truth assignment for a given CNF boolean formula is complete for FNP/\hspace{-1mm}/OptP$[\log n]$, solving an open question by Papadimitriou [{\em Proceedings of the 32nd IEEE Symposium on the Foundations of Computer Science}, 1991, pp.~163--169].}, xxx-references={STOC::Anderson85, STOC::KarpW84, STOC::Luby85, STOC::MulmuleyVV87, FOCS::Papadimitriou91, FOCS::PapadimitriouW85} } @Article{MetivierR95, refkey={C1489}, title={New Results on the Star Problem in Trace Monoids}, author={Yves M{\'e}tivier and Gw{\'e}na{\"e}l Richomme}, pages={240--251}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={We prove that if it is decidable whether $X^*$ is recognizable for a recognizable subset $X$ of a free partially commutative monoid, then it is decidable whether a recognizable subset of a free partially commutative monoid possesses the finite power property. We prove that if any trace of a set $X$ is connected, we can decide whether $X$ possesses the finite power property. Finally, it is also shown that if $X$ is a finite set containing at most four traces or at most two connected traces, it is decidable whether $X^*$ is recognizable.}, xxx-references={FOCS::Simon78} } @Article{GouyJ95, refkey={C1581}, title={Universal Retractions on {$DI$}-Domains}, author={Xavier Gouy and Ying Jiang}, pages={252--257}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={We prove that every $DI$-domain which contains an infinite set of pairwise incompatible elements (in particular, every reflexive $DI$-domain) has an infinite set of universal retractions, which moreover forms a $DI$-domain (when ordered by the stable order) isomorphic to $({\bf N}^{\ast} \cup \{\infty\}, \mid)$ (where $\mid$ is the divisibility relation).}, xxx-references={Amadio95, LICS::AmadioBL86, Berardi91} } @Article{AmirFIPS95, refkey={C1370}, title={Improved Dynamic Dictionary Matching}, author={Amihood Amir and Martin Farach and Ramana M. Idury and Johannes A. La Poutr{\'e} and Alejandro Sch{\"a}ffer}, pages={258--282}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={In the dynamic dictionary matching problem, a dictionary $D$ contains a set of patterns that can change over time by insertion and deletion of individual patterns. The user also presents text strings and asks for all occurrences of any patterns in the text. \par The two main contributions of this paper are: 1) A faster algorithm for dynamic string dictionary matching with bounded alphabets, and 2) A dynamic dictionary matching algorithm for two dimensional texts and patterns. The first contribution is based on an algorithm that solves the general problem of maintaining a sequence of well-balanced parentheses under the operations insert, delete, and find nearest enclosing parenthesis pair. The main new idea behind the second contribution is a novel method to efficiently manipulate failure links for two-dimensional patterns.}, xxx-references={STOC::AmirBF92, FOCS::AmirF91, STOC::DietzS87, FOCS::GalilP92, IduryS95, JACM::McCreight76, FOCS::Weiner73, STOC::Willard82} } @Article{Neiger95, refkey={C1583}, title={Simplifying the Design of Knowledge-Based Algorithms Using Knowledge Consistency}, author={Gil Neiger}, pages={283--293}, journal=iandcomp, month=jun, year=1995, volume=119, number=2, abstract={Processor knowledge is an important tool in the study of distributed computer systems. It has led to better understanding of existing algorithms for such systems and to the development of new {\em knowledge-based\/} algorithms. Some of these algorithms use forms of knowledge (e.g., common knowledge) that cannot be achieved in certain systems. This paper considers {\em alternative interpretations\/} of knowledge under which these forms of knowledge can be achieved. It explores {\em consistent knowledge interpretations\/} and shows how they can be used to circumvent the known impossibility results in a number of cases. This may lead to greater applicability of knowledge-based algorithms.}, xxx-references={DworkM90, JACM::HalpernM90, JACM::HalpernZ92, JACM::NeigerT93} } July 1995 Volume 120, Number 1 @Article{Yamazaki95, refkey={C1282}, title={A Normal Form Problem for Unlabeled Boundary {NLC} Graph Languages}, author={Koichi Yamazaki}, pages={1--10}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We consider an existential problem of a Chomsky type normal form for unlabeled boundary NLC graph languages (Rozenberg and Welzl, 1986a). \par Let $G$ be a boundary NLC grammar, ${\it maxr}(G)$ be the maximum for the sizes of graphs which are the start graph (axiom) and the right-hand sides of production rules in~$G$, and ${\it und}(L(G))$ is the set of underlying unlabeled graphs which are obtained from graphs in the generated language $L(G)$ by removing the labels. Then, in (Rozenberg and Welzl, 1986a), it is an open question whether there exists a positive integer~$k_0$ such that there is a boundary NLC graph grammar~$G$ with ${\it maxr}(G) \le k_0$ and $L = {\it und}(L(G))$ for every unlabeled boundary NLC graph language~$L$. \par We will show that there is an infinite hierarchy in the class of the underlying unlabeled boundary NLC graph languages with respect to the sizes of the graphs appearing in the production rules of the boundary NLC graph grammars that generate the underlying unlabeled boundary NLC graph languages. Finally, we will show that there is no integer~$k_0$ satisfying the above conditions, using a pumping lemma for boundary NLC graph languages.}, xxx-references={RozenbergW86} } @Article{Ben-DavidBM95, refkey={C1063}, title={A Parametrization Scheme for Classifying Models of {PAC} Learnability}, author={Shai Ben-David and Gyora M. Benedek and Yishay Mansour}, pages={11--21}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We present a systematic framework for classifying, comparing and defining models of PAC learnability. Apart from the obvious `uniformity' parameters we present a novel `solid learnability' notion that indicates when the class in question can be successfully learnt by the most straightforward algorithms, namely any consistent algorithm. \par We analyze known models in terms of our new parameterization scheme and investigate the relative strength of notions of learnability that correspond to different parameter values. \par In addition, we consider `proximity' between concept classes. We define notions of `covering' one class by another and show that, with respect to learnability, they play a role similar to the role of reductions in computational complexity; The learnability of a class implies the learnability of any class it covers. We apply the covering technique to resolve some open questions raised in (Benedek and Itai, 1991) and (Linial, Mansour and Rivest, 1991). \par The notions we discuss are information-theoretic---we concentrate on the question of learnability rather than the computational complexity of the learning process.}, xxx-references={Ben-DavidIK95, JACM::BlumerEHW89, LinialMR91} } @Article{RoychowdhurySOK95, refkey={C1493}, title={Vector Analysis of Threshold Functions}, author={Vwani Roychowdhury and Kai-Yeung Siu and Alon Orlitsky and Thomas Kailath}, pages={22--31}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={Viewing $n$-variable Boolean functions as vectors in ${\cal R}^{2^n}$, we invoke basic tools from linear algebra and linear programming to derive new results on the realizability of Boolean functions using threshold gates. Using this approach, we obtain: (1) a lower bound on the number of input functions required by a threshold gate implementing a given function; (2) a lower bound on the error incurred when a Boolean function is approximated by a linear combination of a set of functions; (3) a limit on the effectiveness of a well known lower-bound technique (based on computing correlations among Boolean functions) for the depth of threshold circuits implementing Boolean functions; (4) a construction showing that every Boolean function $f$ of $n$ input variables is a threshold function of polynomially many input functions, none of which is significantly correlated with $f$; (5) generalizations of some known results on threshold-circuit complexity, particularly those that are based on spectral analysis.}, xxx-references={FOCS::Allender89, FOCS::Chow61, STOC::GoldmannK93, FOCS::HajnalMPST87, FOCS::KrauseW91, FOCS::LinialMN89, FOCS::Yao90} } @Article{Edalat95, refkey={C1571}, title={Dynamical Systems, Measures and Fractals via Domain Theory}, author={Abbas Edalat}, pages={32--48}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We introduce domain theory in dynamical systems, iterated function systems (fractals) and measure theory. For a discrete dynamical system given by the action of a continuous map $f:X\to X$ on a metric space $X$, we study the extended dynamical systems $(VX,Vf)$, $(UX,Uf)$ and $(LX,Lf)$ where $V$, $U$ and $L$ are respectively the Vietoris hyperspace, the upper hyperspace and the lower hyperspace functors. We show that if $(X,f)$ is chaotic, then so is $(UX,Uf)$. When $X$ is locally compact $UX$, is a continuous bounded complete dcpo. If $X$ is second countable as well, then $UX$ will be $\omega$-continuous and can be given an effective structure. We show how strange attractors, attractors of iterated function systems (fractals) and Julia sets are obtained effectively as fixed points of deterministic functions on $UX$ or fixed points of non-deterministic functions on $CUX$ where $C$ is the convex (Plotkin) power domain. We also show that the set, $M(X)$, of finite Borel measures on $X$ can be embedded in $PUX$, where $P$ is the probabilistic power domain. This provides an effective framework for measure theory. We then prove that the invariant measure of an hyperbolic iterated function system with probabilities can be obtained as the unique fixed point of an associated continuous function on $PUX$.}, xxx-references={LICS::JonesP89} } @Article{BookLM95, refkey={C1526}, title={The Global Power of Additional Queries to Random Oracles}, author={Ronald V. Book and Jack H. Lutz and David M. {Martin Jr.}}, pages={49--54}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={It is shown that, for every $k\geq0$ and every fixed algorithmically random language $B$, there is a language that is polynomial-time, truth-table reducible in $k+1$ queries to $B$ but not truth-table reducible in $k$ queries in {\em any\/} amount of time to {\em any\/} algorithmically random language $C$. In particular, this yields the separation $\mbox{P$_{k\mbox{-}tt}$} ({\rm RAND}) \subsetneqq \mbox{P$_{(k+1)\mbox{-}tt}$}({\rm RAND})$, where RAND is the set of all algorithmically random languages.}, xxx-references={JACM::Chaitin75, Martin-Lof66} } @Article{Ogihara95, refkey={C1520}, title={Equivalence of {NC$^k$} and {AC$^{k-1}$} closures of {NP} and Other Classes}, author={Mitsunori Ogihara}, pages={55--58}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={Gottlob, (1993, in {\em Proceedings, 34th IEEEE Symposium on Foundations of Computer Sciences}, pp.~42--51), showed that any set recognized by polynomial-size, log-depth trees with queries to SAT is $\le^p_{tt}$-reducible to NP\@. Based on his technique, it is shown for any set~$A$ and any $k \ge 1$ that ${\rm NC}^k(A) \subset {\rm AC}^{k-1}(R^{NP}_{ctt}(A))$, where $R^{NP}_{ctt}(A)$ is the $\le^{NP}_{ctt}$-closure of~$A$. As a consequence, it is shown for any class~$\cal C$ that is closed under $\le^{NP}_{ctt}$-reductions, such as NP and $C_=P$, and for any $k \ge 1$, that ${\rm NC}^k({\cal C}) = {\rm AC}^{k-1}({\cal C})$, which resolves a question that has been left open for a long time.}, xxx-references={BussH91, STOC::Cook71, Cook85, FOCS::Gottlob93}, full-xxx-references={BussH91, STOC::Cook71, Cook85, FOCS::Gottlob93, TCS::LadnerLS75} } @Article{KummerS95, refkey={C1499}, title={Recursion Theoretic Properties of Frequency Computation and Bounded Queries}, author={Martin Kummer and Frank Stephan}, pages={59--77}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={The notion of {\em frequency computation\/} captures the class $\Omega$ of all sets $A$ such that for some $n$, the $n$-fold characteristic function of $A$ can be computed with fewer than $n$ errors. We consider the recursion theoretic properties of $\Omega$ with special emphasis on recursively enumerable sets.}, xxx-references={BeigelGGO93, BeigelKS95a, JACM::BlumerEHW89} } @Article{FaginSV95, refkey={C1325}, title={On Monadic {NP} vs. Monadic co-{NP}}, author={Ronald Fagin and Larry J. Stockmeyer and Moshe Y. Vardi}, pages={78--92}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={It is a well-known result of Fagin that the complexity class NP coincides with the class of problems expressible in existential second-order logic ($\Sigma_1^1$). {\em Monadic NP\/} is the class of problems expressible in monadic $\Sigma_1^1$, i.e., $\Sigma_1^1$ with the restriction that the second-order quantifiers range only over sets (as opposed to ranging over, say, binary relations). We prove that connectivity of finite graphs is not in monadic NP, even in the presence of arbitrary built-in relations of moderate degree (that is, degree $(\log n)^{o(1)}$). This extends earlier results of Fagin and de Rougemont. Our proof uses a combination of three techniques: (1)~an old technique of Hanf for showing that two (infinite) structures agree on all first-order sentences, under certain conditions, (2)~a recent new approach to second-order Ehrenfeucht-Fra{\"\i}ss\'e games by Ajtai and Fagin, and (3)~playing Ehrenfeucht-Fra{\"\i}ss\'e games over random structures (this was also used by Ajtai and Fagin). Regarding (1), we give a version of Hanf's result that is better suited for use as a tool in inexpressibility proofs for classes of finite structures. The power of these techniques is further demonstrated by using them (actually, using just the first two techniques) to give a very simple proof of the separation of monadic NP from monadic co-NP without the presence of built-in relations.}, xxx-references={FOCS::Cosmadakis93, Courcelle90, Immerman86, FOCS::Schwentick94, STOC::Vardi82} } @Article{Bar-NoyDGK95, refkey={C1292}, title={Optimal Amortized Distributed Consensus}, author={Amotz Bar-Noy and Xiaotie Deng and Juan A. Garay and Tiko Kameda}, pages={93--100}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={In this paper we study the behavior of deterministic algorithms when consensus is repeatedly needed, say $k$ times. We show that it is possible to achieve consensus with the optimal number of processors ($n>3t$), and when $k$ is large enough, optimal amortized cost in all other measures: The number of communication rounds $r^*$, the maximal message size $m^*$, and the total bit complexity $b^*$. More specifically, we achieve the following amortized bounds for $k$ consensus instances: $r^*=O(1+{\frac{t}{k}})$, $b^*=O(nt+{\frac{nt^3}{k}})$, and $m^*=O(1+{\frac{t^2}{k}})$. When $k\ge t^2$, then $r^*$ and $m^*$ are $O(1)$ and $b^*=O(nt)$, which is optimal.}, xxx-references={Bar-NoyDDS92, JACM::DolevR85, JACM::DolevRS90, STOC::FeldmanM88, JACM::PeaseSL80} } @Article{DongS95, refkey={C1417}, title={Incremental and Decremental Evaluation of Transitive Closure by First-Order Queries}, author={Guozhu Dong and Jianwen Su}, pages={101--106}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We study the following problem. Suppose $G$ is a graph and ${\it TC}_G$ its transitive closure. If $G'$ is a new graph obtained from $G$ by inserting or deleting an edge $e$, can the new transitive closure ${\it TC}_{G'}$ be defined in first-order logic using $G$, ${\it TC}_G$ and $e$? In this paper, we show that the answer is positive for (1) acyclic graphs (main result), (2) graphs where the vertices of the deleted edge are not in the same strongly-connected component, and (3) graphs where there exists at most one path between each pair of vertices (0-1-path graphs). It is left open whether the new transitive closure is definable in first-order logic for {\em all\/} graphs. We also consider the first-order on-line computation of the dominator relation.}, xxx-references={JACM::EvenS81} } @Article{OHearnR95, refkey={C1624}, title={Kripke Logical Relations and {PCF}}, author={Peter W. O'Hearn and Jon G. Riecke}, pages={107--116}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={Sieber has described a model of PCF consisting of continuous functions that are invariant under certain (finitary) logical relations, and shown that it is fully abstract for closed terms of up to third-order types. We show that one may achieve full abstraction at {\em all\/} types using a form of ``Kripke logical relations'' introduced by Jung and Tiuryn to characterize $\lambda$-definability.}, xxx-references={LICS::BucciarelliE91, CartwrightCF94, LICS::Meyer88, Statman85} } @Article{BeauquierN95, refkey={C1545}, title={Automata on Infinite Trees with Counting Constraints}, author={Dani{\`e}le Beauquier and Damian Niwi{\'n}ski}, pages={117--125}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We investigate finite automata on infinite trees with the usual Muller criterion for the success of an infinite computation path, but with the acceptance paradigm modified in that not all the computation paths need to be successful. Instead, it is required that the number of successful paths must belong to a specified set of cardinals $\Gamma$. We show that Muller automata with the acceptance constraint of the form ``there are at least $\gamma$ accepting paths'' can be always simulated by tree automata with a weaker criterion for successful paths, namely B\"uchi acceptance condition. We also show that this is the most general class of constraints for which a simulation by B\"uchi automata is always possible. Next, we characterize the maximal class of constraints which can be simulated by classical Muller automata (known to be more powerful than B\"uchi automata). The condition requiered of the set $\Gamma$ there, is that the intersection with natural numbers forms a recognizable set. Finally, we exhibit a set of trees which is recognized by a classical B\"uchi automaton but fails to be recognized by any Muller automaton with a non trivial cardinality constraint (i.e., except for $\Gamma = 0$).}, references={focs::EmersonJ1988:328, jcss::VardiW1986:183} } @Article{Neraud95, refkey={C1506}, title={Algorithms for Detecting Morphic Images of a Word}, author={Jean Neraud}, pages={126--148}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={Let $\Delta$ and $\Sigma$ be two disjoint finite alphabets. Given a ``pattern'' $R \in (\Delta\cup\Sigma)^*$, and a ``text'' $w \in \Sigma^*$, we consider the problem that consists in deciding whether there exists a morphism $\phi : (\Delta\cup\Sigma)^*\rightarrow \Sigma^*$, with $\phi(a)=a$ for every constant $a\in \Sigma$, and such that $\phi(R)$ is a factor of $w$. In the general case, this is a NP-complete problem (Angluin, 1980). We study the two following restrictions: (a)~$R$ is an arbitrary one-variable pattern with constants (elements in $\Sigma$); (b)~$R$ is a two-variable pattern without constant. In the first case, we show that the problem may be solved by an $O(|w|^2\ln |w|)$-time algorithm. In the case we present a $O(|w|^2\ln^{2}|w|)$-time algorithm for solving the question.}, xxx-references={Ukkonen85} } @Article{Tung95a, refkey={C1579}, title={The Bounds of {Skolem} Functions and Their Applications}, author={Shih Ping Tung}, pages={149--154}, journal=iandcomp, month=jul, year=1995, volume=120, number=1, abstract={We apply an effective version of the Hilbert's Irreducibility Theorem to obtain upper bounds of the Skolem functions for formulas of the form $\forall x \exists y \forall z\;f(x,y,z) \not= 0$ over~$N$ or~$Z$, where $f$ is a polynomial. We also apply a result of Matijasevic and Robinson to obtain lower bounds of the Skolem functions for formulas of the form $\forall x \exists y \exists z\;f(x,y,z) = 0$. We then use these results to obtain the computational complexities of the winning strategies of diophantine games of length 3 and~4. In addition, we show that if the Generalized Riemann Hypothesis is true, then there is a polynomial time algorithm for the decision problem for diophantine equations with parameters over~$Z$ assuming that the degrees of the equations are bounded. This may be compared with our previous result that without this assumption the decision problem for diophantine equations with parameters is co-NP-complete.} } August 1, 1995 Volume 120, Number 2 @Article{ZeugmannLK95, refkey={C1418}, title={Characterizations of Monotonic and Dual Monotonic Language Learning}, author={Thomas Zeugmann and Steffen Lange and Shyam Kapur}, pages={155--173}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={The present paper deals with monotonic and dual monotonic language learning from positive as well as from positive and negative examples. The three notions of monot\-onicity reflect different formalizations of the requirement that the learner has to produce better and better generalizations when fed more and more data on the concept to be learned. \par The three versions of dual monotonicity describe the concept that the inference device has to produce specializations that fit better and better to the target language. We characterize strong-monotonic, monotonic, weak-monotonic, dual strong-monotonic, dual monotonic and monotonic $\&$ dual monotonic as well as finite language learning from positive data in terms of recursively generable finite sets. These characterizations provide a unifying framework for learning from positive data under the various monotonicity constraints. Moreover, they yield additional insight into the problem of what a natural learning algorithm should look like.}, xxx-references={Angluin80, BlumB75, Fulk90, Gold67, JACM::PittV88, Solomonoff64a, Solomonoff64b} } @Article{ParrowS95, refkey={C1512}, title={Algebraic Theories for Name-Passing Calculi}, author={Joachim Parrow and Davide Sangiorgi}, pages={174--197}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={In a theory of processes the {\em names\/} are atomic data items which can be exchanged and tested for identity. A well-known example of a calculus for name-passing is the $\pi$-calculus, where names additionally are used as communication ports. We provide complete axiomatisations of late and early bisimulation equivalences in such calculi. Since neither of the equivalences is a congruence we also axiomatise the corresponding largest congruences. We consider a few variations of the signature of the language; among these, a calculus of deterministic processes which is reminiscent of sequential functional programs with a conditional construct. Most of our axioms are shown to be independent. The axiom systems differ only by a few simple axioms and reveal the similarities and the symmetries of the calculi and the equivalences.}, xxx-references={HennessyI93, JonssonP93, MilnerPW92a, JACM::Sethi78} } @Article{VollmerW95, refkey={C1519}, title={Complexity Classes of Optimization Functions}, author={Heribert Vollmer and Klaus W. Wagner}, pages={198--219}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={In this paper, complexity classes of functions defined via taking maxima or minima (cf.~the work of Krentel) or taking middle elements (cf.~the work of Toda) are examined. A number of axioms for a class to be a so called {\em p-founded class of optimization functions\/} are given. It is shown that many natural function classes fulfill these axioms. Then these classes are examined concerning their relationship to complexity classes of sets. To this end, complexity preserving operators $\rm S$ and $\rm F$ for encoding function classes into set classes and vice versa are introduced. It is shown, how these operators translate closure properties from one class to another, how they relate operators on classes of functions and classes of sets, and how they encode classes of maximum, minimum, or median functions into well-studied classes of sets. The fixpoints of the compositional operator ${\rm F}\cdot{\rm S}$ are examined and shown to be exactly those function classes ``closed under binary search.'' Let ${\cal F}_1$ and ${\cal F}_2$ be two such fixpoints, and ${\cal K}_1$ and ${\cal K}_2$ be their corresponding classes of sets (i.e.~their images under the operator $\rm S$). Then ${\cal F}_1\subseteq{\cal F}_2$ if and only if ${\cal K}_1\subseteq{\cal K}_2$, and ${\cal F}_1={\cal F}_2$ if and only if ${\cal K}_1={\cal K}_2$. A number of natural classes of functions are shown to be such fixpoints. Thus we build hierachies of function classes with the same inclusional relationships as the polynomial time hierarchy of sets and the counting hierarchy of sets, and we prove many interesting structural properties of these hierarchies.}, xxx-references={STOC::BeigelRS91, BussH91, STOC::Sipser83a, FOCS::Toda90, JACM::Toran91} } @Article{BusscheP95, refkey={C1522}, title={The Expressive Power of Complex Values in Object-Based Data Models}, author={Jan Van den Bussche and Jan Paredaens}, pages={220--236}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={In object-based data models, complex values such as tuples or sets have no special status and must therefore be represented by objects. As a consequence, different objects may represent the same value, i.e., duplicates may occur. This paper contains a study of the precise expressive power required for the representation of complex values in typical object-based data models supporting first-order queries, object creation, and while-loops. Such models are sufficiently powerful to express any reasonable collection of complex values, provided duplicates are allowed. It is shown that in general, the presence of such duplicates is unavoidable in the case of set values. In contrast, duplicates of tuple values can easily be eliminated. A fundamental operation for duplicate elimination of set values, called abstraction, is considered and shown to be a tractable alternative to explicit powerset construction. Other means of avoiding duplicates, such as total order, equality axioms, or copy elimination, are also discussed.}, xxx-references={JACM::KiferLW95, FOCS::BusscheGAG92} } @Article{PanSA95, refkey={C1501}, title={On Parallel Computations with Banded Matrices}, author={Victor Y. Pan and Isdor Sobze and Antoine Atinkpahoun}, pages={237--250}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={We devise parallel algorithms for solving a banded linear system of equations and for computing the determinant of a banded matrix, substantially improving the previous record computational complexity estimates of [E]. Our algorithms are in $NC$ or $RNC$ and support new record bounds on the parallel time complexity of these computations and simultaneously the bounds on their {\em potential work\/} (the product of time and processor bounds), which match (within constant or logarithmic factors) the record sequential time bounds for the same computations. Moreover, these algorithms are in $NC^1$ or $RNC^1$ if the bandwidth is a constant.}, xxx-references={FOCS::Eberly92, JACM::Hockney65, FOCS::KaltofenP92, STOC::PanR85, JACM::Schwartz80} } @Article{Power95, refkey={C1457}, title={Why Tricategories?}, author={A. J. Power}, pages={251--262}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={We outline a logical framework, based on the theory of categories with extra structure, for logics that arise in computer science. We list many representative examples of structures that have arisen, then we classify them in terms of equational, and the more general essentially algebraic, structure. In both cases, we outline the main results and their significance for the logical framework. This study gives rise to coherence questions. We explain the issues, and then outline the category theoretic concepts, such as tricategories, that arise in resolving the coherence problems.}, xxx-references={LICS::HarperHP87, RobinsonR88} } @Article{PierroMP95, refkey={C1345}, title={Negation as Instantiation}, author={Alessandra Di Pierro and Maurizio Martelli and Catuscia Palamidessi}, pages={263--278}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={We propose a new negation rule for logic programming which derives existentially closed negative literals, and we define a version of completion for which this rule is sound and complete. The rule is called ``Negation As Instantiation" (NAI). According to it, a negated atom succeeds whenever all the branches of the SLD-tree for the atom either fail or instantiate the atom. The set of the atoms whose negation is inferred by the NAI rule is proved equivalent to the complement of $T_C\!\downarrow\!\omega$, where $T_C$ is the immediate consequence operator extended to non-ground atoms (Falaschi et al., 1989). The NAI rule subsumes negation as failure on ground atoms, it excludes floundering and can be efficiently implemented. We formalize this way of handling negation in terms of SLDNI-resolution (SLD-resolution with Negation as Instantiation). Finally, we amalgamate SLDNI-resolution and SLDNF-resolution, thus obtaining a new resolution procedure which is able to treat negative literals with both existentially quantified variables and free variables, and we prove its correctness.}, xxx-references={FalaschiLMP93} } @Article{BorealeN95, refkey={C1452}, title={Testing Equivalence for Mobile Processes}, author={Michele Boreale and Rocco De Nicola}, pages={279--303}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={The impact of applying the testing approach to a calculus of processes with dynamic communication topology is investigated. A proof system is introduced that consists of two groups of laws: those for strong observational equivalence plus those needed to deal with invisible actions. Soundness and completeness of this proof system w.r.t. a testing preorder are shown. A fully abstract denotational model for the language is presented that takes advantage of reductions of processes to normal forms.}, xxx-references={HennessyI93, MilnerPW92a, MilnerPW92b, ParrowS95} } @Article{BeigelKS95b, refkey={C1606}, title={Approximable Sets}, author={Richard Beigel and Martin Kummer and Frank Stephan}, pages={304--314}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={Much structural work on NP-complete sets has exploited SAT's d-self-reducibility. In this paper we exploit the additional fact that SAT is a d-cylinder to show that NP-complete sets are p-superterse unless P${}={}$NP. In fact, every set that is NP-hard under polynomial-time $n^{o(1)}$-tt reductions is p-superterse unless P${}={}$NP. In particular no p-selective set is NP-hard under polynomial-time $n^{o(1)}$-tt reductions unless P${}={}$NP. In addition, no easily countable set is NP-hard under Turing reductions unless P${}={}$NP. Self-reducibility does not seem to suffice for our main result: in a relativized world, we construct a d-self-reducible set in NP${}-{}$P that is polynomial-time 2-tt reducible to a p-selective set.}, xxx-references={AmirG88, BeigelGGO93, BeigelKS95a} } @Article{Tung95b, refkey={C1443}, title={Computational Complexity of Arithmetical Sentences}, author={Shih Ping Tung}, pages={315--325}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={Arithmetical sentences are the sentences containing usual logical symbols and arithmetical symbols $+$, $\cdot$, and constants of~$Z$. An arithmetical sentence~$\phi$ is called an $\exists\forall$ sentence if and only if $\phi$ is logically equivalent to a sentence of the form $\exists x \forall y\; \psi(x, y)$ where $\psi(x, y)$ is a quantifier free formula. It is shown that the decision problems of determining $\forall\exists$ sentences true in~$N$ or~$Z$, respectively, are co-NP-complete, whereas the decision problem of determining $\forall\exists$ sentences true only in~$Q$ is in~P\@. Consequently, the decision problems of determining $\exists\forall$ sentences true in~$N$ or~$Z$, respectively, are NP-complete. Also, the decision problem of determining $\exists\forall$ sentences true in~$Q$ is in~P\@.}, xxx-references={STOC::Cook71, STOC::StockmeyerM73} } @Article{BussT95, refkey={C1548}, title={Lower Bounds on Universal Traversal Sequences Based on Chains of Length Five}, author={Jonathan Buss and Martin Tompa}, pages={326--329}, journal=iandcomp, month={1~} # aug, year=1995, volume=120, number=2, abstract={Universal traversal sequences for cycles require length \(\Omega(n^{1.43})\), improving the previous bound of \(\Omega(n^{1.33})\). For \(d \geq 3\), universal traversal sequences for $d$-regular graphs require length \(\Omega(d^{0.57} n^{2.43})\). For constant $d$, the best previous bound was \(\Omega(n^{2.33})\).}, xxx-references={FOCS::AleliunasKLLR79, STOC::ChandraRRST89} } August 15, 1995 Volume 121, Number 1 @Article{HemaspaandraJ95, refkey={C1409}, title={Defying Upward and Downward Separation}, author={Lane A. Hemaspaandra and Sudhir K. Jha}, pages={1--13}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={``Downward separation'' results show that when small classes collapse, larger ones also collapse. For example, Stockmeyer proved that if $\mathrm{P} = \mathrm{NP}$, then the polynomial hierarchy collapses to P, and this result itself holds in every relativized world. In contrast, we construct a relativized world in which the exponential-time limited nondeterminism hierarchy does not display such behavior: its lower levels collapse yet its upper levels separate. ``Upward separation'' results typically show that polynomial-time classes differ on sparse or tally sets if and only if their exponential analogs differ. For example, Hartmanis, Immerman, and Sewelson proved that $\mathrm{NP}-\mathrm{P}$ contains sparse sets if and only if $\mathrm{E} \neq \mathrm{NE}$, and this result itself holds in every relativized world. In contrast, we construct relativized worlds in which probabilistic classes do not display upward separation, e.g., a world $A$ in which $\mathrm{BPP}^A-\mathrm{P}^A$ contains sparse sets even though $\mathrm{BPE}^A = \mathrm{E}^A$. We also construct a relativized world $B$ in which $\mathrm{NP}^B$ has $\mathrm{P}^B$-immune sparse sets yet $\mathrm{NE}^B$ is not $\mathrm{E}^B$-immune. On the other hand, we provide a structural sufficient condition for upward separation.}, xxx-references={Book74, FOCS::Gurevich83, FOCS::Hartmanis83, HartmanisIS85, FOCS::ImpagliazzoT89, FOCS::MeyerS72, STOC::Sipser83a} } @Article{LongpreW95, refkey={C1509}, title={On Symmetry of Information and Polynomial Time Invertibility}, author={Luc Longpr{\'e} and Osamu Watanabe}, pages={14--22}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={The amount of information contained in a string~$x$ abut a string~$y$---$I(x, y)$---is the difference between the quantity of information in~$x$ when $x$ has to be printed from nothing and when $x$ has to be printed using the string~$y$: $K(x) - K(x|y)$. \par Symmetry of information states that \[I(x,y) = I(y,x) \pm O(\log|xy|).\] We consider whether symmetry of information holds in a polynomial time bounded environment. Intuitively, this problem is related to the complexity of inverting a polynomial time computable function. We give some evidence supporting this intuition, by proving the following relations: \begin{itemize} \item If polynomial time symmetry of information holds, then for any polynomial~$p$, there is a polynomial time algorithm that computes the shortest $p$-time description of a string for ``almost all'' strings. \item If polynomial time symmetry of information holds, then every polynomial time computable length preserving function is probabilistic polynomial time invertible for ``almost all'' strings in its domain. \item If P${}={}$NP (i.e., every polynomial time computable function is polynomial time invertible), then polynomial time symmetry of information holds. \end{itemize}}, xxx-references={STOC::Sipser83a} } @Article{SantisCP95, oldkey={SantisDP95}, refkey={C1521}, title={Zero-Knowledge Arguments and Public-Key Cryptography}, author={Alfredo De Santis and Giovanni Di Crescenzo and Giuseppe Persiano}, pages={23--40}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={In this work we consider the Diffie-Hellman public-key model in which an additional short random string is shared by all users. This, which we call Public-Key Public-Randomness (PKPR) model, is very powerful as we show that it supports simple non-interactive implementations of important cryptographic primitives. We give a non-interactive implementation of Oblivious Transfer in the PKPR model. Our implementation is secure against receivers with unlimited computational power. Building on this result, we show that all languages in NP have Perfect Zero-Knowledge Arguments in the PKPR model.}, xxx-references={STOC::Ben-OrGW88, STOC::BlumFM88, FOCS::BrassardC86, FOCS::BrassardCR86, STOC::ChaumCD88, FOCS::SantisP92, STOC::FeigeFS87, FOCS::FeigeLS90, STOC::Fortnow87, STOC::GoldreichMW87, STOC::GoldreichOP94, STOC::HalpernR83, STOC::Kilian88, FOCS::KilianMO89} } @Article{Ben-AsherLPS95, refkey={C1300}, title={The Complexity of Reconfiguring Network Models}, author={Y. Ben-Asher and K.-J. Lange and D. Peleg and A. Schuster}, pages={41--58}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={This paper concerns some of the theoretical complexity aspects of the reconfigurable network model. The computational power of the model is investigated under several variants, depending on the type of switches (or switch operations) assumed by the network nodes. Computational power is evaluated by focusing on the set of problems computable in constant time in each variant. A hierarchy of such problem classes corresponding to different variants is shown to exist and is placed relative to traditional classes of complexity theory.}, xxx-references={STOC::FortuneW78, MoshellR79, STOC::Nisan92, FOCS::NisanSW92, JACM::Reif84} } @Article{GlabbeekSS95, refkey={C1439}, title={Reactive, Generative and Stratified Models of Probabilistic Processes}, author={Rob J. van Glabbeek and Scott A. Smolka and Bernhard Steffen}, pages={59--80}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={We introduce three models of probabilistic processes, namely, reactive, generative and stratified. These models are investigated within the context of PCCS, an extension of Milner's SCCS in which each summand of a process summation expression is guarded by a probability and the sum of these probabilities is 1. For each model we present a structural operational semantics of PCCS and a notion of bisimulation equivalence which we prove to be a congruence. We also show that the models form a hierarchy: the reactive model is derivable from the generative model by abstraction from the relative probabilities of different actions, and the generative model is derivable from the stratified model by abstraction from the purely probabilistic branching structure. Moreover the classical nonprobabilistic model is derivable from each of these models by abstraction from all probabilities.}, xxx-references={LICS::GlabbeekSST90, LICS::JonesP89, LICS::JonssonL91} } @Article{Gottlob95, refkey={C1536}, title={The Complexity of Default Reasoning under the Stationary Fixed Point Semantics}, author={Georg Gottlob}, pages={81--92}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={Stationary default extensions have recently been introduced by Przymusinska and Przymusinsky as an interesting alternative to classical extensions in Reiter's default logic. An important property of this new approach is that the set of all stationary extensions has a unique minimal element. In this paper we investigate the computational complexity of the main reasoning tasks in propositional stationary default logic, namely, cautious and brave reasoning. We show that cautious reasoning is complete for $\Delta_2^P$ while brave reasoning is ${\bf\Sigma}_2^P$-complete. We also show that for {\em normal\/} default theories, the least fixed point iteration used to compute the unique minimal stationary extension is noticeably simplified. Based on this observation we show that cautious reasoning with normal defaults is complete for ${\bf P}^{{\bf NP}[\log n]}$. This is the class of decision problems solvable in polynomial time with a logarithmic number of queries to an oracle in {\bf NP}\@.}, xxx-references={BidoitF91, FOCS::Gottlob93, STOC::StockmeyerM73} } @Article{AdlemanHK95, refkey={C1109}, title={Efficient Checkers for Number-Theoretic Computations}, author={Leonard M. Adleman and Ming-Deh Huang and Kireeti Kompella}, pages={93--102}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={Manuel Blum has recently proposed a new approach to the problem of program correctness, the {\em program checker}. Here, {\em efficient\/} program checkers are presented for two important number theory problems, integer GCD and modular exponentiation. The former result answers an open problem posed by Blum. The latter result paves the way for more robust cryptographic programs, as modular exponentiation is the basis for several cryptosystems. Taken together, these results lay the foundation for more reliable number-theoretic programs.}, xxx-references={FOCS::BeigelBFG91, STOC::BlumK89, STOC::BlumLR90, STOC::GemmellLRSW91, STOC::Yao90} } @Article{Clote95, refkey={C1357}, title={Cutting plane and {Frege} proofs}, author={Peter Clote}, pages={103--122}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={The cutting plane refutation system $CP$ for propositional logic is an extension of resolution and is based on showing the non-existence of solutions for families of integer linear inequalities. We define the system $CP^+$, a modification of the cutting plane system, and show that $CP^+$ can polynomially simulate Frege systems $F$. In [S. R. Buss and P. Clote. Cutting planes, connectivity, and threshold logic. Submitted, 1993], it is shown that $F$ polynomially simulates $CP^+$, so both systems are polynomially equivalent. \par To establish this result, propositional formulas are represented in a natural manner, and an effective version of cut elimination is proved for the system $CP^+$. Additionally, an alternative proof is given which directly translates $F$ proofs into $CP^+$. Thus, within a polynomial factor, one can simulate classical propositional logic proofs using the cut rule by refutation-style proofs involving linear inequalities with the ceiling operation. \par Since there are polynomial size cutting plane $CP$ proofs for many elementary combinatorial principles (pigeonhole principle, $k$-equipartition principle), we propose propositional versions of the Paris-Harrington theorem, Kanamori-McAloon theorem, and variants as possible candidates for combinatorial tautologies which may require exponential size cutting plane and Frege proofs.}, xxx-references={FOCS::Ajtai88, STOC::BeameIKPPW92, LICS::Clote92, STOC::Cook75, LICS::ImpagliazzoPU94} } @Article{Stewart95, refkey={C1182}, title={Completeness of Path-Problems via Logical Reductions}, author={Iain A. Stewart}, pages={123--134}, journal=iandcomp, month={15~} # aug, year=1995, volume=121, number=1, abstract={We show that some well-known path-problems remain complete for the respective complexity class quantifier-free projections (these are extremely restricted logical reductions).} } September 1995 Volume 121, Number 2 @Article{MateescuSSY95, refkey={C1608}, title={P, {NP} and the {Post} Correspondence Problem}, author={Alexandru Mateescu and Arto Salomaa and Kai Salomaa and Sheng Yu}, pages={135--142}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={We define a variant of the Post Correspondence Problem, the machine-oriented Post Correspondence Problem or MOPCP, especially suitable for complexity considerations. All recursively enumerable sets can be represented in terms of instances of MOPCP and, moreover, deterministic and nondeterministic time and space complexities have their natural counterpart in the representation. This leads to PCP-related complexity classes, for instance, the time complexity classes PCP-P and PCP-NP\@. Using a bounded delay injectivity condition on one of the morphisms of a PCP instance, we obtain an exact characterization of P\@. In this characterization, determinism corresponds exactly to the bounded delay condition and no reference is made to computations of any sort. A weaker bounded delay requirement gives rise to an infinite (possibly collapsing) hierarchy between P and NP\@.}, xxx-references={JACM::Culik79} } @Article{ChristensenHS95, refkey={C1511}, title={Bisimulation Equivalence is Decidable for All Context-Free Processes}, author={S{\o}ren Christensen and Hans H{\"u}ttel and Colin Stirling}, pages={143--148}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={A result originally due to Baeten, Bergstra, and Klop shows that strong bisimulation equivalence for normed BPA processes is \emph{decidable}. On the other hand, Huynh and Tian, and Groote and H\"uttel, have proved that all other standard equivalences are undecidable for normed BPA and thus for BPA in general. The open problem remaining has been whether bisimulation is decidable for the \emph{full} BPA language. In this paper, we answer this question in the affirmative, using a proof technique based on the proof by Caucal of the decidability of language equivalence for simple algebraic grammars. The decision procedure relies on our main result, extending that of Caucal, that the maximal bisimulation of any BPA transition graph is finitely representable as a Thue congruence. The decision procedure consists of two semi-decision procedures, one testing for non-bisimilarity and one testing for bisimilarity.}, xxx-references={JACM::BaetenBK93, BergstraK84, LICS::HuttelS91} } @Article{Vogler95b, refkey={C1497}, title={Timed Testing of Concurrent Systems}, author={Walter Vogler}, pages={149--171}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={This paper is concerned with timing considerations for concurrent systems where the time needed by the individual actions is not known beforehand; it has long been suspected that the power of partial order semantics is needed here. We develop a suitable testing scenario to study this idea. With some view of timed behaviour, we can confirm that interval semiword semantics, a special partial order semantics, is indeed what can be observed with timed tests. With another view, our testing scenariou leads to timed-refusal-trace semantics; this is a non-interleaving semantics, but it seems that it cannot be represented with partial orders in a meaningful way.}, xxx-references={JACM::BrookesHR84, LICS::CleavelandZ91} } @Article{BachmairGLS95, refkey={C1524}, title={Basic Paramodulation}, author={Leo Bachmair and Harald Ganzinger and Christopher Lynch and Wayne Snyder}, pages={172--192}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={We introduce a class of restrictions for the ordered paramodulation and superposition calculi (inspired by the {\em basic\/} strategy for narrowing), in which paramodulation inferences are forbidden at terms introduced by substitutions from previous inference steps. In addition we introduce restrictions based on term selection rules and redex orderings, which are general criteria for delimiting the terms which are available for inferences. These refinements are compatible with standard ordering restrictions and are complete without paramodulation into variables or using functional reflexivity axioms. We prove refutational completeness in the context of deletion rules, such as simplification by rewriting (demodulation) and subsumption, and of techniques for eliminating redundant inferences.}, xxx-references={JACM::HsiangR91, JACM::Huet80, JACM::Slagle74, JACM::WosRCS67} } @Article{McAllesterKO95, refkey={C1478}, title={A Proof of Strong Normalization of {$F_2$}, {$F_\omega$} and Beyond}, author={D. McAllester and J. Ku{\v{c}}an and D. F. Otth}, pages={193--200}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={We present an evaluation technique for proving strong normalization (SN). We use the technique to give SN proofs for $F_2$, $F$-bounded quantification, subtypes, and $F_\omega$. The evaluation technique derives SN as a corollary of the soundness of the typing rules under an appropriate evaluation semantics. The evaluation semantics yields simpler type sets than those used in the earlier SN proofs. The type sets discussed here form a complete lattice under classical union and intersection. The simplified type sets allow a simplified treatment of a variety of type constructors.}, xxx-references={Mitchell88} } @Article{JainSV95, refkey={C1619}, title={Finite Identification of Functions by Teams with Success Ratio $\frac{1}{2}$ and Above}, author={Sanjay Jain and Arun Sharma and Mahendran Velauthapillai}, pages={201--213}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={Consider a scenario in which an algorithmic machine, {\bf M}, is being fed the graph of a computable function $f$. {\bf M} is said to {\em finitely identify\/} $f$ just in case after inspecting a finite portion of the graph of $f$ it emits its first conjecture which is a program for $f$, and it never abandons this conjecture thereafter. A {\em team\/} of machines is a multiset of such machines. A team is said to be successful just in case each member of some nonempty subset, of predetermined size, of the team is successful. The ratio of the number of machines required to be successful to the size of the team is referred to as the {\em success ratio\/} of the team. The present paper investigates the finite identification of computable functions by teams of learning machines. The results presented complete the picture for teams with success ratio $\frac{1}{2}$ and greater. \par It is shown that at success ratio $\frac{1}{2}$, introducing redundancy in the team can result in increased learning power. In particular it is established that larger collections of functions can be learned by employing teams of $4$ machines and requiring at least $2$ to be successful than by employing teams of $2$ machines and requiring at least $1$ to be successful. Surprisingly, it is also shown that introducing further redundancy at success ratio $\frac{1}{2}$ does not yield any extra learning power. In particular, it is shown that the collections of functions that can be finitely identified by a team of $2m$ machines requiring at least $m$ to be successful is the same as: \begin{itemize} \item the collections of functions that can be finitely identified by a team of $4$ machines requiring at least $2$ to be successful, if $m$ is even, and \item the collections of functions that can be identified by a team of $2$ machines requiring at least $1$ to be successful, if $m$ is odd. \end{itemize} These latter results require development of sophisticated simulation techniques.}, xxx-references={BlumB75, JACM::Blum67, Gold67, OshersonSW86, JACM::Pitt89, PittS88, JACM::Smith82} } @Article{LynchV95, refkey={C1475}, title={Forward and Backward Simulations: {I}. Untimed Systems}, author={Nancy Lynch and Frits Vaandrager}, pages={214--233}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={A unified, comprehensive presentation of simulation techniques for verification of concurrent systems is given, in terms of a simple untimed automaton model. In particular, (1) refinements, (2) forward and backward simulations, (3) hybrid forward-backward and backward-forward simulations, and (4) history and prophecy relations are defined. History and prophecy relations are abstract versions of the history and prophecy variables of Abadi and Lamport, as well as the auxiliary variables of Owicki and Gries. Relationships between the different types of simulations, as well as soundness and completeness results, are stated and proved. Finally, it is shown how invariants can be incorporated into all the simulations. \par Even though many results are presented here for the first time, this paper can also be read as a survey (in a simple setting) of the research literature on simulation techniques. \par The development for untimed automata is designed to support a similar development for timed automata. In Part~II of this paper, it is shown how the results of this paper can be carried over to the setting of timed automata.}, xxx-references={LICS::NicolaV90a, JACM::NicolaV95, KlarlundS93} } @Article{BaetenBS95, refkey={C1401}, title={Axiomatizing Probabilistic Processes: {ACP} with Generative Probabilities}, author={J. C. M. Baeten and J. A. Bergstra and S. A. Smolka}, pages={234--255}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={This paper is concerned with finding complete axiomatizations of probabilistic processes. We examine this problem within the context of the process algebra ACP and obtain as our end-result the axiom system $pr{\rm{ACP}}^-_I$, a version of ACP whose main innovation is a probabilistic asynchronous interleaving operator. Our goal was to introduce probability into ACP in as simple a fashion as possible. Optimally, ACP should be the homomorphic image of the probabilistic version in which the probabilities are forgotten. \par We begin by weakening slightly ACP to obtain the axiom system ${\rm{ACP}}^-_I$. The main difference between ACP and ${\rm{ACP}}^-_I$ is that the axiom $x + \delta = x$, which does not yield a plausible interpretation in the generative model of probabilistic computation, is rejected in ${\rm{ACP}}^-_I$. We argue that this does not affect the usefulness of ${\rm{ACP}}^-_I$ in practice, and show how ACP can be reconstructed from ${\rm{ACP}}^-_I$ with a minimal amount of technical machinery. \par $pr{\rm{ACP}}^-_I$ is obtained from ${\rm{ACP}}^-_I$ through the introduction of probabilistic alternative and parallel composition operators, and a process graph model for $pr{\rm{ACP}}^-_I$ based on {\em probabilistic bisimulation\/} is developed. We show that $pr{\rm{ACP}}^-_I$ is a sound and complete axiomatization of probabilistic bisimulation for finite processes, and that $pr{\rm{ACP}}^-_I$ can be homomorphically embedded in ${\rm{ACP}}^-_I$ as desired. \par Our results for ${\rm{ACP}}^-_I$ and $pr{\rm{ACP}}^-_I$ are presented in a modular fashion by first considering several subsets of the signatures. We conclude with a discussion about adding an iteration operator to $pr{\rm{ACP}}^-_I$.}, xxx-references={BergstraK84, LICS::JonssonL91, LarsenS91, LICS::GlabbeekSST90} } @Article{Freund95, refkey={C1533}, title={Boosting a Weak Learning Algorithm by Majority}, author={Yoav Freund}, pages={256--285}, journal=iandcomp, month=sep, year=1995, volume=121, number=2, abstract={We present an algorithm for improving the accuracy of algorithms for learning binary concepts. The improvement is achieved by combining a large number of hypotheses, each of which is generated by training the given learning algorithm on a different set of examples. Our algorithm is based on ideas presented by Schapire in his paper ``The strength of weak learnability'', and represents an improvement over his results. The analysis of our algorithm provides general upper bounds on the resources required for learning in Valiant's polynomial PAC learning framework, which are the best general upper bounds known today. We show that the number of hypotheses that are combined by our algorithm is the smallest number possible. Other outcomes of our analysis are results regarding the representational power of threshold circuits, the relation between learnability and compression, and a method for parallelizing PAC learning algorithms. We provide extensions of our algorithms to cases in which the concepts are not binary and to the case where the accuracy of the learning algorithm depends on the distribution of the instances.}, xxx-references={FOCS::AslamD93, JACM::BlumerEHW89, HausslerKLW91, FOCS::HausslerLW88, STOC::Kearns93, FOCS::KearnsS90, JACM::KearnsV94} } October 1995 Volume 122, Number 1 @Article{GabbrielliLM95, refkey={C1423; PN2479}, title={Observable Behaviors and Equivalences of Logic Programs}, author={Maurizio Gabbrielli and Giorgio Levi and Maria Chiara Meo}, pages={1--29}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={We first introduce a general semantic scheme for logic programs which provides a uniform framework for defining different compositional semantics parametrically wrt a given notion of observability. The equivalence of the operational (top-down) and fixpoint (bottom-up) construction of the semantics is ensured by the scheme (provided a congruence property is verified). We then define several observational equivalences on logic programs and investigate how they are related. the equivalences are based on various observables (successful derivations, computed answers, partial computed answers and call patterns) and on a notion of program composition. For each observational equivalence we study the relation with suitable formal semantics, by investigating correctness and full abstraction properties. All the semantics are obtained as instances of the general scheme.}, references={HTCS::Apt1990, ALP::BarbutiCGM1992, TOPLAS::BarbutiGL1993, CLP::BossiBF1993, POPL::BossiB1993:359, JLOGP::BossiC1993, JLOGP::BossiGLM1994, TCS::BossiGLM1994, ICLP::BossiM1991, TR::Clark1979, TR::CodishDY1990, POPL::CousotC1977, MISC::Debray1994, STACS::DenisD1991, JSYMC::Eder1985, TCS::FalaschiL1990, TCS::FalaschiLPM1989:289, IC::FalaschiLMP1993, JLOGC::GabbrielliDL1995:133, CLP::GabbrielliL1991, ICALP::GabbrielliL1991, SLP::GabbrielliLM1992, POPL::GaifmanS1989, LICS::GaifmanS1989, FGCS::KawamuraK1988, TCS::LassezM1984, MISC::LassezM1988, BOOK::Lloyd1987, JLOGP::LloydS1991, MISC::Maher1988, CLP::MancarellaP1988, IP::Marriottn1989, SLP::OKeefe1985, ICALP::Palamidessi1990, CLP::Turi1991, JACM::EmdenK1976, CLP::WolframML1984} } @Article{AikenKW95, refkey={C1504; PN2500}, title={Decidability of Systems of Set Constraints with Negative Constraints}, author={Alexander Aiken and Dexter Kozen and Ed Wimmers}, pages={30--44}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={Set constraints are relations between sets of terms. They have been used extensively in various applications in program analysis and type inference. Recently, several algorithms for solving general systems of positive set constraints have appeared. In this paper we consider systems of mixed positive and negative constraints, which are considerably more expressive than positive constraints alone. We show that it is decidable whether a given such system has a solution. The proof involves a reduction to a number-theoretic decision problem that may be of independent interest.}, xxx-references={LICS::AikenW92, FOCS::CharatonikP94, FOCS::GilleronTT93, LICS::HeintzeJ90, LICS::Stefansson94} } @Article{ChenH95, refkey={C1259; PN2493}, title={Recurrence Domains: Their Unification and Application to Logic Programming}, author={Hong Chen and Jieh Hsiang}, pages={45--69}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={In this paper we present a formalism for finitely representing infinite sets of terms. This formalism, called {\em $\rho$-terms}, enables us to reason finitely about certain recursive types. We present an extension of Horn logic programs, called $\rho$-Prolog, which allows a finite schematization of infinitely many clauses via predicates with $\rho$-terms as arguments. We show that for every $\rho$-Prolog program there is an equivalent Horn logic program. That is, incorporating $\rho$-terms into first order logic programming does not change its denotational semantics. Computationally, however, $\rho$-Prolog has the advantages of (1)~representing infinitely many answers finitely, (2)~avoiding repetition in computation and thus achieving better efficiency, (3)~allowing infinite queries, and (4)~avoiding certain non-termination of Prolog programs. The $\rho$-terms play a similar role as regular-trees (Mishra and Reddy, 1985) and sort-expressions (Comon, 1990) in explicitly defining abstract data types. It differs from the others in that it allows us to define certain non-regular-tree sets such as $\{\, (a^n, b^n, c^n): n \in \cal{N}\,\}$. We present a finite and complete algorithm for unification between $\rho$-terms, with which we can also compute the intersection of the sets defined by $\rho$-terms.}, references={ICLP::BruynoodgeJ1988, JLOGP::ChandraH1985, CTRS::ChenHK1990, SIGMOD::ChomickiI1989:174, MISC::Colmerauer1982, RTA::Comon1989, ICALP::Comon1990, MST::Comon1995, JLOGP::GoguenM1984, TR::GoguenM1985, POPL::HeintzeJ1990, POPL::JaffarL1987, POPL::MishraR1985, JACM::NelsonO1980, MATHA::Oberschelp1962, LPAR::Salzer1992, THESIS::Schmidt-Schauss1989, ECAI::Walther1983} } @Article{CoppoG95, refkey={C1638; PN2498}, title={Principal Types and Unification for a Simple Intersection Type Systems}, author={Mario Coppo and Paola Giannini}, pages={70--96}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={In this paper we introduce a decidable restriction of the intersection type discipline. The restriction is based on a uniform principle rather than on a notion of rank. For this system we give a type checking algorithm that we prove to be sound and complete. An extended language of types with labelled intersections and intersection schemes is needed to describe the principal type of terms which turns out to be unique modulo a set of equations between labels. The unification algorithm for labelled types, that extends first order unification, could be used as a basis to define inference algorithms for other (more powerful) systems with intersection.}, references={POPL::AikenWL1994, BOOK::Barendregt1984, JSYML::BarendregtCD1983:931, CTCS::BoerioC1992, ACMCS::CardelliW1985:471, MFCS::Coppo1980:194, NDJFL::CoppoD1980:685, MISC::CoppoDV1980:480, TCS::CoppoF1993, CAAP::CoppoG1992:102, BOOK::CurryF1958, POPL::DamasM1982, TACS::DamianiG1994, TACS::Gardner1994:555, LICS::GianniniR1988:61, TACS::GianniniR1991:18, THESIS::Girard1971, BOOK::GordonMW1979, POPL::HankinM1994, TAMS::Hindley1969:29, BOOK::HindleyS1980, MISC::Kahn1988, LICS::KfouryTU1989:98, LICS::KfouryT1990:2, FPLCA::KuoM1989, POPL::Leivant1983:88, TCS::Leivant1986:51, JCSS::Milner1978:348, ISP::Mycroft1984:217, TCS::Rocca1988:181, TCS::RoccaV1984:151, FPLCA::Turner1985:1, TLCA::Urzyczyn1993:418, TCS::Bakel1992:135, THESIS::Bakel1993, LICS::Wells1994:176} } @Article{DeganoG95, refkey={C1384; PN2463}, title={A Causal Operational Semantics of Action Refinement}, author={Pierpaolo Degano and Roberto Gorrieri}, pages={97--119}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={A TCSP-like concurrent language is extended with an operator for action refinement which plays a r\^ole similar to that of procedure-call for sequential languages. The language is given a denotational semantics, that fully expresses causality, in terms of Causal Trees. These are Synchronization Trees where each arc has a richer labelling containing, besides an action name, also the set of backward pointers to those arcs ``causing'' the present action. An operational semantics reflecting causality is also defined in SOS style by a causal transition system, the unfoldings of which are causal trees. The denotational and operational semantics agree up to causal bisimulation, that is proved to be a congruence for all the operators of the calculus; notably, for the refinement one. Also, a complete set of axioms is provided that characterizes the congruence classes of causal bisimulation for finite agents. The main result of the paper is an operational semantics firmly based on a view of action refinement as purely semantic substitution. Therefore, its operational definition provides a ``parallel copy rule,'' i.e. the concurrent analogous of the classic ``copy rule'' for sequential languages.}, references={LICS::AcetoBV1992, IC::AcetoH1993, ICALP::AcetoH1991, JACM::AcetoH1992, BEATCS::Boudol1989, TR::BoudolC1991, JACM::BrookesHR1984:560, POPL::BloomIM1988, TCS::BergstraK1985, CWITR::BakkerV1992, IC::BakkerZ1982, ICALP::DarondeauD1989, TCS::DarondeauD1993, EPSP::DarondeauD1990, REX::DeganoNM1989, TR::DeganoG1991, TR::DeganoG1992, REX::DeganoGR1992, LMCS::FrancezHT1985, CPCM::Glabbeek1990, REX::GlabbeekG1990, TR::GlabbeekG1990, TR::GoltzGR1992, FUNDI::Gorrieri1992, IC::GrooteV1992, JACM::HennessyM1985, LICS::JategaonkarM1993, CONCUR::JanssenPZ1991, JACM::Milner1979, BOOK::Milner1989, REX::NielsenEL1989, MISC::Nivat1982, TR::Plotkin1981, MISC::Park1981, THESIS::Rensink1993, FUNDI::RabinovichT1988, TCS::Vogler1993, REX::Winskel1989} } @Article{Spreen95, refkey={C1517; PN2495}, title={On Some Decision Problems in Programming}, author={Dieter Spreen}, pages={120--139}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={One of the central problems in programming is the correctness problem, i.e., the question whether a program computes a given function. We choose a rather general formal semantical framework, effectively given topological $T_0$-spaces, and study the problem to decide whether an element of the space is equal to a fixed element. Moreover, we consider the problems to decide of two elements whether they are equal and whether one approximates the other in the specialization order. They are one-one equivalent for a large class of spaces, including effectively given Scott domains. All these problems are undecidable. In most cases they are complete in some level of the arithmetical and/or the Boolean hierarchy. The complexity respectively depends on whether the fixed element is not finite and whether the space contains a nonfinite element. The problem to decide whether an element is not finite is potentially $\Pi^0_2$-complete and for domain-like spaces the membership problem of any nonempty set of nonfinite elements that intersects the effective closure of its complement is $\Pi^0_2$-hard. If the given element is finite or the space contains only finite elements, the complexity also depends on the location of the given element in the specialization order and/or the boundedness of the set of lengths of all decreasing chains of basic open sets.}, references={MISC::Ceitin1962:295, THESIS::Deil1983, ALGEL1::Ersov1968:47, ALGEL1::Ersov1968:15, ALGEL1::Ersov1972:367, MISC::Ersov1972:523, ALGEL1::Ersov1973:369, ZMLGM::Ersov1973:289, ZMLGM::Ersov1975:473, IC::GianniniL1984:36, PAMS::Hay1966:106, BOOK::Kushner1985, MISC::Lacombe1959:129, ZMLGM::Lewis1971:291, THESIS::Moschovakis1963, FUNDI::Moschovakis1964:215, BOOK::Odifreddi1989, MISC::Plotkin1983, SICOMP::Scott1976:522, TR::Scott1981, TAMS::Shapiro1956:281, ICALP::Smyth1983:662, MISC::Smyth1987, MFPLS::Smyth1988:236, BOOK::Soare1987, MISC::Spreen1990:363, MISC::Spreen1991:231, TR::Spreen1993, TCS::Stoltenberg-HansenT1991:1, TR::WeihrauchD1980} } @Article{MuthukrishnanR95, refkey={C1408; PN2497}, title={String Matching Under a General Matching Relation}, author={S. Muthukrishnan and H. Ramesh}, pages={140--148}, journal=iandcomp, month=oct, year=1995, volume=122, number=1, abstract={In standard string matching, each symbol matches only itself. In other string matching problems, e.g., the string matching with ``don't-cares'' problem, a symbol may match several symbols. In genearl, an arbitrary many-to-many matching relation might hold between symbols. We consider a general string matching problem in which such a matching relation is specified and those positions in a text~$t$, of lenght~$n$, are sought at which the pattern~$p$, of length~$m$, matches under this relation. \par Depending upon the existence of a simple and easily recognizable property in the given matching relation, we show that string matching either requires linear (i.e., $O(n+m)$) time or is at least as hard as boolean convolution. As an application, we show that the matching relations of several independently studied string matching problems do indeed fall into the latter (hard) category. \par We also give a generic string matching algorithm that works for any matching relation and has complexity $o(nm)$ except for very ``large'' matching relations.}, xxx-references={CACM::BoyerM77, FOCS::Kosaraju89a} } November 1, 1995 Volume 122, Number 2 @Article{deLiguoroP95, refkey={C1454; PN2494}, title={Non Deterministic Extensions of Untyped {$\lambda$}-calculus}, author={Ugo de'Liguoro and Adolfo Piperno}, pages={149--177}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={The main concern of this paper is the study of the interplay between functionality and non-determinism. We ask whether the analysis of parallelism in terms of sequentiality and non-determinism, which is usual in the algebraic treatment of concurrency, remains correct in presence of functional application and abstraction. \par We argue in favor of a distinction between between non-determinism and parallelism, due to the conjunctive nature of the former in contrast with the disjunctive character of the latter. This is the basis of our analysis of the operational and denotational semantics of non-deterministic $\lambda$-calculus, which is the classical calculus plus a choice operator, and of our election of bounded indeterminacy as the semantical counterpart of conjunctive non-determinism. This leads to operational semantics based on the idea of \emph{must} preorder, coming from the classical theory of solvability and from the theory of process algebras. To characterize this relation, we build a model using the inverse limit construction over non-deterministic algebras, and we prove it fully abstract using a generalization of B\"ohm trees. We further prove conservativity theorems for the equational theory of the model and for other theories, related to non-deterministic $\lambda$-calculus, with respect to classical $\lambda$-theories.}, references={AbramskyO1993:159, JACM::GoguenTWW1977, JACM::AptP1986, ic::BarbaneraDd1995:202, Boudol1994:51, Hennessy1994:55, MilnerPW1992:1, MilnerPW1992:41, Moggi1991:55, LICS::Ong1993, LICS::Sangiorgi1992} } @Article{BarbutiCGM95, refkey={C1601; PN2496}, title={Oracle Semantics for {Prolog}}, author={Roberto Barbuti and Michael Codish and Roberto Giacobazzi and Michael J. Maher}, pages={178--200}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={This paper proposes to specify semantic definitions for logic programming languages such as Prolog in terms of an oracle which specifies the control strategy and identifies which clauses are to be applied to resolve a given goal. The approach is quite general. It is applicable to Prolog to specify both operational and declarative semantics as well as other logic programming languages. \par Previous semantic definitions for Prolog typically encode the sequential depth-first search of the language into various mathematical frameworks. Such semantics mimic a Prolog interpreter in the sense that following the ``leftmost'' infinite path in the computation tree excludes computation to the right of this path from being considered by the semantics. The basic idea in this paper is to abstract away from the sequential control of Prolog and to provide a declarative characterization of the clauses to apply to a given goal. The decision whether or not to apply a clause is viewed as a query to an oracle which is specified from within the semantics and reasoned about from outside. This approach results in simple and concise semantic definitions which are more useful for arguing the correctness of program transformations and providing the basis for abstract interpretations than previous proposals.}, references={JACM::AptE1982, AptP1993:109, POPL::BarbutiCGL1992, TOPLAS::BarbutiGL1993, TOPLAS::CharlierH1994, TOPLAS::DebrayW1989, JACM::EmdenK1976, FalaschiLMP1993:86, TOPLAS::Griswold1982, POPL::JaffarL1987, POPL::SaraswatR1990} } @Article{McColm95, refkey={C1187; PN2502}, title={Pebble Games and Subroutines in Least Fixed Point Logic}, author={G. L. McColm}, pages={201--220}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={We characterize the Least Fixed Point logic (FO + LFP) as a class of pebble game programs. Such a program can be characterized unambiguously as a structure of recursive subroutines. These programs can be described as flowchart-like digraphs. Concentrating on fixedpoints of a bounded number of quantifier alternations, we partition FO + LFP into an infinite nonlinear hierarchy of queries, composed of expressibility classes characterized by alternations within recursive subroutines.}, references={STOC::AbiteboulV1991, POPL::AhoU1979, FOCS::AjtaiG1989, JACM::ChandraKS1981, FOCS::GradelM1992, HarelK1984:118, PODS::KolaitisV1990, PODS::LakshmananM1989} } @Article{Herrmann95, refkey={C1256; PN2501}, title={On the Undecidability of Implications between Embedded Multivalued Database Dependencies}, author={Christian Herrmann}, pages={221--235}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={The implication and finite implication problem for embedded multivalued database dependencies are both shown to be algorithmically undecidable. The proof is by an interpretation of semigroup word problems via systems of permuting equivalence relations into database dependencies. In contrast, it is shown that for each fixed premise $H$ one has a decision procedure for implications $H \Rightarrow F$.}, references={STOC::ChandraLM1981, GurevichL1982:69, JACM::SagivDPF1981, JACM::SagivW1982} } @Article{PillaipakkamnattR95, refkey={C1627; PN2505}, title={Read-Twice {DNF} Formulas Are Properly Learnable}, author={Krishnan Pillaipakkamnatt and Vijay Raghavan}, pages={236--267}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={We show that read-twice DNF formulas---Boolean formulas in disjunctive normal form in which each variable appears at most twice---are exactly and properly learnable in polynomial time. Our algorithm uses membership queries and proper equivalence queries, and is based on a simple, new characterization of minimal read-twice DNF formulas. The algorithm improves on earlier results of Hancock and Aizenstein and Pitt which showed that read-twice DNF formulas are learnable using more powerful equivalence queries, i.e., where the hypotheses could be arbitrary DNF formulas. We also improve on the time-complexity of these earlier algorithms. \par Other results which may be of independent interest outside of learning follow directly from this paper. Specifically, we show that read-twice DNF formulas can be tested for equivalence in polynomial time, and that the smallest read-twice formula equivalent to a given one can be found in polynomial time.}, references={JACM::AngluinHK1993, FOCS::AizensteinHP1992, STOC::AngluinK1991, FOCS::AizensteinP1991, JACM::BlumerEHW1989, FOCS::Bshouty1993, CACM::Valiant1984:1134} } @Article{BrownG95, refkey={C1244; PN2510}, title={A Categorical Linear Framework for {Petri} Nets}, author={Carolyn Brown and Doug Gurr}, pages={268--285}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={This paper presents a framework for giving a compositional theory of Petri nets using category theory. An integral part of our approach is the use of linear logic in specifying and reasoning about Petri nets. \par We construct categories of nets based on de Paiva's {\em dialectica category\/} models of linear logic (de~Paiva, 1989), and exploit the structure of de Paiva's models to give constructions on nets. We compare our categories of nets with others in the literature, and show how some of the most widely-studied categories can be expressed within our framework. \par Taking a category of elementary nets as an example we show how this approach yields both existing and novel constructions on nets and discuss their computational interpretation.}, references={LICS::BrownG1990, FOCS::GuptaP1993, LICS::MeseguerM1988, Winskel1987:197, LICS::Winskel1988} } @Article{FokkinkK95, refkey={C1544; PN2499}, title={An Effective Axiomatization for Real Time {ACP}}, author={Wan Fokkink and Steven Klusener}, pages={286--299}, journal=iandcomp, month={1~} # nov, year=1995, volume=122, number=2, abstract={Baeten and Bergstra added real time to ACP, and introduced the notion of integration, which expresses the possibility of an action happening within a time interval. In order to axiomatize this feature, they needed an ``uncountable'' axiom. This paper deals with prefix integration, and integration is parametrized by conditions, which are inequalities between linear expressions of variables. We present an axiomatization for process terms, and propose a strategy to decide bisimulation equivalence between process terms, by means of this axiomatization.}, references={FACS::BaetenB1991, IC::Schneider1995:193, tcs::AlurD1994:183, tcs::Stoughton1988:317} } November 15, 1995 Volume 123, Number 1 @Article{JanickiK95, refkey={C1480; PN2503}, title={Semantics of Inhibitor Nets}, author={Ryszard Janicki and Maciej Koutny}, pages={1--16}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We discuss an abstract semantics of concurrent systems generalising causal partial orders. The new semantics employs relational structures----called stratified order structures---which comprise causal partial orders and weak causal partial orders. Stratified order structures can be represented by certain equivalence classes of step sequences---comtraces---directly generalising Mazurkiewicz traces. As system model we use Elementary Net Systems with inhibitor arcs and show that stratified order structures can provide an abstract semantics which is consistent with their operational semantics expressed in terms of step sequences. Two different types of operational rules are considered. We also construct occurrence nets to enable the generation of stratified order structures for a given run of the net.}, references={TCS::AalbersbergR1988, TR::Agerwala1974, TCS::BestD1987, PNPM::Billington1989, LNCS::CartierF1969, ICATPN::ChiolaDF1991, ATPN::ChristiansenH1993, STACS::Diekert1991, BOOK::Fraisse1986, LICS::GaifmanP1987, BOOK::Hoare1985, ACTAI::Janicki1987, DIMACS::JanickiK1990, PARLE::JanickiK1991, CONCUR::JanickiK1991, TCS::JanickiK1993, FSTTCS::JanickiK1993, BOOK::JanickiL1992, ACMCAN::Jorg1990, POPL::Lamport1985, JACM::Lamport1986:313, JACM::Lamport1986:327, TR::Mazurkiewicz1977, LNCS::Mazurkiewicz1986, MISC::MontanariR1992, PIEEE::Murata1989, DC::NielsenRT1990, BOOK::Peterson1991, IJPP::Pratt1986, BOOK::Reisig1985, FUNDM::Szpilrajn1930, RAIRO::Vogler1991, LNCS::Winskel1982} } @Article{HromkovicKSW95, refkey={C1528; PN2506}, title={Gossiping in Vertex-Disjoint Paths Mode in {$d$}-Dimensional Grids and Planar Graphs}, author={Juraj Hromkovi{\v{c}} and Ralf Klasing and Elena A. St{\"o}hr and Hubert Wagener}, pages={17--28}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={This paper continues with the study of the communication modes introduced in [J.~Hromkovi\v{c}, R.~Klasing, E.A.~St\"ohr, ``Dissemination of Information in Vertex-Disjoint Paths Mode, Part 1: General Bounds and Gossiping in Hypercube-Like Networks'', Technical Report No.~tr-ri-93-129, University of Paderborn. (Extended abstract presented at WG'93.)] as a generalization of the standard one-way and two-way modes allowing to send messages between processors of interconnection networks via vertex-disjoint paths in one communication step. The complexity of communication algorithms is measured by the number of communication steps (rounds). Here, the complexity of gossiping in grids and in planar graphs is investigated. The main results are the following: \begin{enumerate} \item Effective one-way and two-way gossip algorithms for $d$-dimensional grids, $d \geq 2$, are designed. \item The lower bound $2\log_2 n - \log_2 k - \log_2 \log_2 n - 4$ is established on the number of rounds of every two-way gossip algorithm working on any graph of $n$ nodes and vertex bisection $k$. This proves that the designed two-way gossip algorithms on $d$-dimensional grids, $d \geq 3$, are almost optimal, and it also shows that the 2-dimensional grid belongs to the best gossip graphs among all planar graphs. \item Another lower bound proof is developed to get some tight lower bounds on one-way ``well-structured'' gossip algorithms on planar graphs (to the best of the authors' knowledge, to date all gossip algorithms designed in vertex-disjoint paths mode have been ``well-structured''). \end{enumerate}}, references={MST::AielloLMN1991, JPDC::Ben-AsherPRS1991, SICOMP::KrummeCV1992:111, JALGO::DiksDSV1993, IEEETC::DallyS1987, SPAA::EvenM1989, NETW::Farley1980, DAM::FeldmannHMMM1994, HICSS::FunkeLMFB1992, NETW::HedetniemiHL1988, ALGOR::HromkovicJM1993, MISC::HromkovicKMP1993, TR::HromkovicKS1993, COMPNET::KermaniK1979, SIDMA::KlaweL1992, DM::Knodel1975, BOOK::Leighton1992, SPAA::LeisersonADFGHHKPWWYZ1992:272, SIDMA::LiptonT1979} } @Article{FarachT95, refkey={C1535; PN2504}, title={Fast Comparison of Evolutionary Trees}, author={Martin Farach and Mikkel Thorup}, pages={29--37}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={Constructing evolutionary trees for species sets is a fundamental problem in biology. Unfortunately, there is no single agreed upon method for this task, and many methods are in use. Current practice dictates that trees be constructed using different methods and that the resulting trees then be compared for consensus. It has become necessary to automate this process as the number of species under consideration has grown. We study the {\em Unrooted Maximum Agreement Subtree Problem} ({\tt UMAST}) and its rooted variant ({\tt RMAST}). \par The {\tt UMAST} problem is as follows: given a set $A$ and two trees $T_0$ and $T_1$ leaf-labeled by the elements of $A$, find a maximum cardinality subset $B$ of $A$ such that the restrictions of $T_0$ and $T_1$ to $B$ are topologically isomorphic. Our main result is an $O(n^{2+o(1)})$ time algorithm for the {\tt UMAST} problem. We also derive an $O(n^2)$ time algorithm for the {\tt RMAST} problem. The previous best algorithm for both these problems has running time $O(n^{4.5+o(1)})$.}, references={FOCS::AgarwalaF1993, FOCS::KeselmanA1994, ICALP::BodlaenderFW1992, BMBIO::Day1987, AMNAT::Farris1972, QRBIO::Felsenstein1982, JCLASS::FindenG1985, ALGOR::FarachKW1995:155, SCIENCE::FitchM1976, SODA::FarachT1994, FOCS::FarachT1994, SICOMP::GabowT1989, SICOMP::HarelT1984, JCLASS::KubickaKM1994, SODA::KannanLW1990, BOOK::Knuth1973, MOLBIOEV::SaitouN1987, BOOK::SokalS1963, IPL::SteelW1993} } @Article{CaiCDF95, refkey={C1640; PN2508}, title={On the Structure of Parameterized Problems in {NP}}, author={Liming Cai and Jianer Chen and Rodney Downey and Michael Fellows}, pages={38--49}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={Fixed-parameter intractability of optimization problems in NP is studied based on computational models with limited nondeterminism. Strong evidence is shown that many NP optimization problems are not fixed-parameter tractable and that the fixed-parameter intractability hierarchy (the $W$-hierarchy) does not collapse.}, references={MISC::AbrahamsonDF1993, APAL::AbrahamsonDF1995, FOCS::AbrahamsonEFM1989:210, FOCS::AggarwalCS1987:204, BOOK::BalcazarDG1988, SCTC::BeigelG1994, STOC::BodlaenderFH1994, HTCS::BoppanaS1990, SICOMP::BussG1993, TCS::CaiC1995, LNCS::CaiCDF1994, APAL::CaiCDF1995, JACM::ChandraKS1981:114, IPL::Chen1991, MST::DiazT1990, COLT::DowneyEF1993, SCTC::DowneyF1992, MISC::DowneyF1993, ESA::FellowsHW1993, STOC::FellowsL1989, LNCS::FellowsK1993, SCTC::PapadimitriouY1993, JACM::PippengerF1979, STOC::Sipser1983:61, TCS::Wolf1994} } @Article{BiochI95, refkey={C1634; PN2509}, title={Complexity of Identification and Dualization of Positive {Boolean} Functions}, author={Jan C. Bioch and Toshihide Ibaraki}, pages={50--63}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We consider in this paper the problem of identifying $\min T(f)$ and $\max F(f)$ of a positive (i.e., monotone) Boolean function $f$, by using membership queries only, where $\min T(f)$ ($\max F(f)$) denotes the set of minimal true vectors (maximal false vectors) of $f$. It is shown that the existence of an incrementally polynomial algorithm for this problem is equivalent to the existence of the following algorithms, where $f$ and $g$ are positive Boolean functions. \begin{enumerate} \item An incrementally polynomial algorithm to dualize $f$. \item An incrementally polynomial algorithm to self-dualize $f$. \item A polynomial algorithm to decide if $f$ and $g$ are mutually dual. \item A polynomial algorithm to decide if $f$ is self-dual. \item A polynomial algorithm to decide if $f$ is saturated. \item A polynomial algorithm in $|\min T(f)| + |\max F(f)|$ to identify $\min T(f)$ only. \end{enumerate} Some of these are already well known open problems in the respective fields. Other related topics, including various equivalent problems encountered in hypergraph theory and theory of coteries (used in distributed systems), are also discussed.}, references={ML::Angluin1988, JACM::AngluinHK1993, BOOK::AnthonyB1992, RFTIC::Benzaken1966, TCS::BertolazziS1987, TR::Bioch1993, TR::BiochI1993, TR::BiochI1994, ISA::BorosHIK1991, DAM::Crama1987, AOR::CramaHI1988, TR::EiterG1991, TR::FredmanK1994, USSRCMMP::Gainanov1984, JACM::Garcia-MolinaB1985, BOOK::GareyJ1979, BOOK::Halmos1963, IEEETPDS::IbarakiK1993, IPL::JohnsonYP1988, ISAAC::KavvadiasPS1993, CACM::Lamport1978:558, SICOMP::LawlerLK1980, ISAAC::MakinoI1994, JCSS::MannilaR1986, BOOK::Muroga1971, DAM::PeledS1985, AI::Reiter1987, STOC::Schaefer1978, CACM::Valiant1984:1134, BOOK::Wegener1987} } @Article{FreivaldsKS95, refkey={C1684; PN2514}, title={On the Intrinsic Complexity of Learning}, author={R\={u}si\c{n}\v{s} Freivalds and Efim B. Kinber and Carl H. Smith}, pages={64--71}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={A new view of learning is presented. The basis of this view is a natural notion of reduction. We prove completeness and relative difficulty results. An infinite hierarchy of intrinsically more and more difficult to learn concepts is presented. Our results indicate that the complexity notion captured by our new notion of reduction differs dramatically from the traditional studies of the complexity of the algorithms performing learning tasks.}, references={ML::Angluin1988, TAP::Barzdins1974, IC::BlumB1975:125, COLT::CholakDFGKKKS1992:180, TCS::CaseS1983, TAP::FreivaldsK1977, COLT::FreivaldsKS1993, LNCS::Freivalds1975, COLT::Freivalds1990, LNCS::Freivalds1991, IC::FreivaldsS1993:237, IC::Gold1967:447, COLT::GasarchP1989, COLT::JainS1994, EWCLT::JainS1995, BOOK::MachteyY1978, SCTC::PittW1988, JSYML::Rogers1958, BOOK::Smith1994, CACM::Valiant1984:1134, IWAII::Warmuth1989} } @Article{BastH95, refkey={C1220; PN2511}, title={Fast Parallel Space Allocation, Estimation and Integer Sorting}, author={Hannah Bast and Torben Hagerup}, pages={72--110}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={The following problems are shown to be solvable in $O(\log^* n)$ time with optimal speedup with high probability on a randomized CRCW PRAM using $O(n)$ space: \begin{itemize} \item Space allocation: Given $n$ nonnegative integers $x_1,\ldots,x_n$, allocate $n$ nonoverlapping blocks of consecutive memory cells of sizes $x_1,\ldots,x_n$ from a base segment of $O(\sum_{j=1}^n x_j)$ consecutive memory cells; \item Estimation: Given $n$ integers in the range $1\,.\,.\,n$, compute ``good'' estimates of the number of occurrences of each value in the range $1\,.\,.\,n$; \item Semisorting: Given $n$ integers $x_1,\ldots,x_n$ in the range $1\,.\,.\,n$, store the integers $1,\ldots,n$ in an array of $O(n)$ cells such that for all $i\in\{1,\ldots,n\}$, all elements of $\{\, j:1\le j\le n$ and $x_j=i \,\}$ occur together, separated only by empty cells; \item Integer chain-sorting: Given $n$ integers $x_1,\ldots,x_n$ in the range $1\,.\,.\,n$, construct a linked list containing the integers $1,\ldots,n$ such that for all $i,j\in\{1,\ldots,n\}$, if $i$ precedes $j$ in the list, then $x_i\le x_j$. \end{itemize} Moreover, given slightly superlinear processor and space bounds, these problems or variations of them can be solved in constant time with high probability. \par As a corollary of the integer chain-sorting result, it follows that $n$ integers in the range $1\,.\,.\,n$ can be sorted in $O({{\log n}/{\log\log n}})$ time with optimal speedup with high probability.}, references={STOC::AjtaiB1984, JACM::AlonM1994, MFCS::BastDH1992, SPAA::BastH1991, JACM::BeameH1989, SICOMP::BerkmanV1993, IC::BhattDHPRS1991, CMSJB::Bollobas1987, IWGTCCS::ChaudhuriH1994, MFCS::ChlebusDHR1988, ICFCT::ChlebusDHR1989, IC::ColeV1989, ALGOR::FichRW1988, THESIS::Gil1990, JPDC::Gil1994, FOCS::GilMV1991, FOCS::Goodrich1991, ALGOR::Grolmusz1991, FOCS::GrolmuszR1987, STACS::Hagerup1992:45, STACS::Hagerup1992:259, TR::Hagerup1992, IPL::Hagerup1992, HICSS::HagerupK1993, SPAA::HagerupR1990, FOCS::HagerupR1992, IPL::HagerupR1990, SODA::MacKenzie1992, STOC::MatiasV1991, MISC::McDiarmid1989, JALGO::Ragde1993, SICOMP::RajasekaranR1989, CFSTTCS::Raman1990, TR::Raman1991, SICOMP::Reischuk1985, JALGO::ShiloachV1982:57, STOC::Stockmeyer1983:118, HTCS::Valiant1990} } @Article{LuccioP95, refkey={C1611; PN2507}, title={Approximate Matching for Two Families of Trees}, author={Fabrizio Luccio and Linda Pagli}, pages={111--120}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We study approximate matching between $h$-ary trees (ordered trees whose the nodes have exactly $h$ sons), and ordered arbitrary trees, using a string representation of trees. For two $h$-ary trees $P$, $T$, the \emph{subtree distance} is the number of subtrees to be inserted in~$P$ in place of empty nodes, or to be deleted from~$P$, to obtain~$T$. We consider the problem of finding all the occurrences of $P$ in~$T$, with bounded distance $k$. A known sequential solution requires $O(h|P|+h|T|+k|T|)$ time. We show that the problem can be solved in $O(\log h + \log|P| + \log|T| + k)$ parallel time, in a CRCW-PRAM with $O(h(|P| + |T|))$ processors. For arbitrary ordered trees we solve an extended version of the classical tree pattern matching problem. We define the \emph{leaf distance} between two trees $P$, $T$ as the total number of subtrees to be inserted in~$P$ in place of its leaves, or to be deleted from~$P$ leaving leaves in their place, to obtain~$T$. We show how all the occurrences of~$P$ as a subtree of~$T$, with bounded distance~$k$, can be determined in $O(|P|+k|T|)$ sequential time, and in $O(\log |P| + \log |T| + k)$ parallel time in a CRCW-PRAM with $O(|P|+|T|)$ processors. We also discuss an extension of the above problems to labelled trees.}, references={TOPLAS::AhoGT1989, ALGOR::ApostolicoILSV1988, CAAP::CaiPT1990, FOCS::DubinerGM1990, JCOMP::GalilG1988, SICOMP::HarelT1984, STOC::Hariharan1994, JACM::HoffmannO1982, HTCS::KarpR1990, CAAP::KilpelanenM1991, FOCS::Kosaraju1989:178, JALGO::LandauV1989, CAAP::LuccioP1991, IPL::LuccioP1991, IPL::Makinen1989, ICALP::RameshR1988, BOOK::SankoffK1983, SICOMP::SchieberV1988, IPL::Selkow1977:184, JALGO::ShashaZ1990, IC::SteyaertF1983:19, BOOK::Stryer1988, JACM::Tai1979:422, TCS::Zaks1980, SICOMP::ZhangS1989} } @Article{FortnowL95, refkey={C1645; PN2515}, title={Circuit Lower Bounds {\em \`a la\/} {Kolmogorov}}, author={Lance Fortnow and Sophie Laplante}, pages={121--126}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={In a recent paper, Razborov (Razborov, 1993) gave a new combinatorial proof of H{\aa}stad's switching lemma (H{\aa}stad, 1989), eliminating the probabilistic argument altogether. In this paper we adapt his proof and propose a Kolmogorov complexity-style switching lemma, from which we derive the probabilistic switching lemma as well as a Kolmogorov complexity-style proof of circuit lower bounds for parity.}, references={MISC::Beame1994, HTCS::BoppanaS1990, MST::FurstSS1984, MISC::Hastad1989, BOOK::LiV1993, MISC::Razborov1993, FOCS::Yao1985:1} } @Article{BerkmanIP95, refkey={C1561; PN2513}, title={The Subtree Max Gap Problem with Application to Parallel String Covering}, author={Omer Berkman and Costas S. Iliopoulos and Kunsoo Park}, pages={127--137}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We introduce the {\em subtree max gap\/} problem. Consider a rooted tree $T$ with $n$ leaves whose internal nodes have at least two children. Each leaf is associated with a real number. For each internal node $v$, let $A_v$ be the set of numbers associated with the leaves in the subtree rooted at $v$, regarded as points on the $x$-axis. The subtree max gap problem is to compute the maximum distance (gap) between any two consecutive points of $A_v$ for every internal node $v$ of $T$. Our algorithm for the subtree max gap problem follows a series of reductions to other combinatorial problems which are interesting on their own merit. The algorithm runs in $O(\log n)$ time using $n$ processors on the CREW PRAM. \par The subtree max gap problem plays a central role in the parallel solution of the string covering problem. Recently, Iliopoulos, Moore and Park (1993) gave an $O(n\log n)$ time sequential algorithm for the string covering problem. Neither parallelizing the above sequential algorithm nor using known techniques from algorithms on strings seems to yield an efficient parallel algorithm for string covering. Our parallel algorithm thus follows a new approach, using suffix trees and reducing the string covering problem to the subtree max gap problem. The algorithm runs in $O(\log n)$ time using $n$ processors on the CRCW PRAM, thereby matching the number of operations in (Iliopoulos, Moore and Park, 1993).}, references={TCS::ApostolicoE1993, IPL::ApostolicoFI1991, ALGOR::ApostolicoILSV1988, JALGO::BerkmanSV1993, SICOMP::BerkmanV1993, TCS::BlumerBHECS1985, TR::BreslauerG1992, SICOMP::Cole1988, TCS::Crochemore1986, DISCG::EdelsbrunnerGS1989, ESA::GasieniecP1994, TR::Gonzalez1975, SICOMP::HarelT1984, STOC::Hariharan1994, IPL::Hershberger1989, SCPM::IliopoulosMP1993, SICOMP::KnuthMP1977, JACM::LadnerF1980:831, TR::ManberT1982, JACM::McCreight1976:262, TFCGCAD::Overmars1988, BOOK::PreparataS1985, JALGO::Ragde1993, SICOMP::RajasekaranR1989, STOC::SahinalpV1994, SICOMP::SchieberV1988, SICOMP::TarjanV1985, BMBIO::ZukerS1984} } @Article{Takada95, refkey={C1648; PN2521}, title={A Hierarchy of Language Families Learnable by Regular Language Learning}, author={Yuji Takada}, pages={138--145}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We shall establish the existence of a hierarchy of language families in which the learning problem for each family is reduced to the learning problem for regular languages. The hierarchy is defined inductively by controlling certain type of even linear grammars with languages in one family to yield languages in the next larger family. Each family contains the family of regular languages and has a nontrivial language such as $\{\, a_1^na_2^n\cdots a_{2^i}^n \mid n\geq 0 \,\}$, where $i$ is a nonnegative integer and each $a_j$ is a symbol. Thus this boosts the learnability of learning algorithms for regular languages.}, references={IC::AmarP1964:283, JACM::Angluin1982:741, IC::Angluin1987:87, EATCS::DassowP1989, ALT::GarciaVO1990, BOOK::Harrison1978, JCSS::Khabbaz1974, IC::Moriya1973:139, MISC::OncinaG1992, WAII::Pitt1989, PATREC::RadhakrishnanN1988, LNAI::SempereG1994, IPL::Takada1988, JIP::Takada1988, IJPRAI::Takada1994, LNAI::Takada1995, HICSS::YokomoriIK1994} } @Article{Bshouty95, refkey={C1525; PN2512}, title={Exact Learning {Boolean} Functsion via the Monotone Theory}, author={Nader H. Bshouty}, pages={146--153}, journal=iandcomp, month={15~} # nov, year=1995, volume=123, number=1, abstract={We study the learnability of boolean functions from membership and equivalence queries. We develop the Monotone Theory that proves \par 1) Any boolean function is learnable in polynomial time in its minimal DNF size, its minimal CNF size and the number of variables $n$. \par In particular, \par 2) Decision trees are learnable. \par Our algorithms are in the model of exact learning with membership queries and unrestricted equivalence queries. The hypotheses to the equivalence queries and the output hypotheses are depth~3 formulas.}, references={ML::Angluin1988, IEEETIT::Roth1992, ML::AngluinFP1992, FOCS::AizensteinHP1992:523, STOC::AngluinK1991:444, FOCS::AizensteinP1991, COLT::AizensteinP1992, IPL::Blum1992, MISC::Bshouty1993, STOC::BshoutyHH1992, COLT::BshoutyHH1992, TR::Karpinski1991, STOC::BlumR1992:382, MISC::CohenZ1993, IC::EhrenfeuchtH1989:231, COLT::Hancock1993, STOC::KushilevitzM1991, FOCS::LinialMN1989, ML::Littlestone1988, COLT::PillaipakkamnattR1994, TR::PillaipakkamnattR1994, ML::Rivest1987, COLT::SchapireS1993, CACM::Valiant1984:1134} } December 1995 Volume 123, Number 2 @Article{AttiyaDW95, refkey={C1577; PN2523}, title={Connection Management without Retaining Information}, author={Hagit Attiya and Shlomi Dolev and Jennifer L. Welch}, pages={155--171}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={Managing a connection between two hosts is an important service to provide in order to make the network useful for many applications. The two main subproblems are the management of serial incarnations of a connection and the transfer of messages within an incarnation. This paper investigates whether it is necessary for connection management protocols to retain state information across node crashes and between incarnations. The following results were obtained: \begin{itemize} \item When information is not retained across node crashes, incarnation management is not possible at all. \item When information is not retained between incarnations, incarnation management is possible if the network is FIFO and not possible if the network is non-FIFO. \item When information is not retained across node crashes, message transfer can be accomplished in networks that lose packets if the network is FIFO \emph{and} the protocol is allowed a variable length grace period after a crash during which it need not deliver messages. However, message transfer cannot be accomplished if the network is non-FIFO or the grace period allowed is fixed. \item When information is not retained cross node crashes, message transfer can be accomplished in networks that do not lose packets if the network is FIFO \emph{or} the protocol need not be FIFO\@. Message transfer is not possible when the network is non-FIFO and the protocol must be FIFO. \item If the network has bounded capacity, then message transfer is possible without using stable storage. This indicates, somewhat surprisingly, that there is a data link initialization protocol that can withstand node crashes without stable storage. \end{itemize}}, references={JACM::AfekAFFLMWZ1994, FOCS::AwerbuchPV1991, JACM::FeketeLMS1993} } @Article{DawarH95, refkey={C1667; PN2516}, title={The Expressive Power of Finitely Many Generalized Quantifiers}, author={Anuj Dawar and Lauri Hella}, pages={172--184}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={We consider extensions of first order logic (FO) and fixed point logic (FP) by means of generalized quantifiers in the sense of Lindstr\"om. We show that adding a finite set of such quantifiers to FP fails to capture PTIME, even over a fixed signature strengthening earlier results in (Hella, 1992) and (Kolaitis and V\"a\"an\"anen, 1992). We also prove a stronger version of this result for PSPACE, which enables us to establish that PSPACE${}\neq{}$FO on any infinite class of ordered structures, a weak version of the ordered conjecture formulated in (Kolaitis and Vardi, 1992). These results are obtained by defining a notion of element type for bounded variable logics with finitely many generalized quantifiers. Using these, we characterize the classes of finite structures over which the infinitary logic $L^\omega_{\inf\omega}$ extended by a finite set of generalized quantifiers {\bf Q} is no more expressive than first order logic extended by the quantifiers in {\bf Q}.}, references={DawarLW1995:160, LICS::GurevichIS1994, LICS::Hella1992, LICS::HellaKL1994, Immerman1986:86, ImmermanL1995:103, LICS::KolaitisV1992:348, LICS::KolaitisV1992:46, KolaitisV1992:258, STOC::Vardi1982} } @Article{BeckerDW95, refkey={C1530; PN2522}, title={On the Relation Between {BDD}s and {FDD}s}, author={Bernd Becker and Rolf Dreschler and Ralph Werchner}, pages={185--197}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={Data structures for Boolean functions build an essential component of design automation tools, especially in the area of logic synthesis. The state of the art data structure is the ordered binary decision diagram (OBDD), which results from general binary decision diagrams (BDDs), also called branching programs, by ordering restrictions. In the context of EXOR-based logic synthesis another type of decision diagram (DD), called (ordered) functional decision diagram ((O)FDD) becomes increasingly important. \par We study the relation between (ordered, free) BDDs and FDDs. Both, BDDs and FDDs, result from DDs by defining the represented function in different ways. If the underlying DD is complete, the relation between both types of interpretation can be described by a Boolean transformation $\tau$. This allows us to relate the FDD-size of $f$ and the BDD-size of $\tau(f)$ also in the case that the corresponding DDs are free or ordered, but not (necessarily) complete. We use this property to derive several results on the computational power of OFDDs and OBDDs. Symmetric functions are shown to have efficient representations as OBDDs and OFDDs as well. Classes of functions are given that have exponentially more concise OFDDs than OBDDs, and vice versa. Finally, we determine the complexity of some standard operations if OFDDs are used for the representation of Boolean functions.}, references={STOC::AjtaiBHKPRST1986:30, IEEETC::Akers1978, MISC::BeckerD1993, ECDA::BeckerD1994, EDTC::BeckerD1995, IFIP::BeckerDT1993, MISC::BeckerDT1994, BOOK::Berlekamp1968, ISCS::BrglezF1985, BOOK::Sangiovanni-Vincentelli1984, IEEETC::Bryant1986, IEEETC::Bryant1991, ACMCS::Bryant1992, MISC::BesslichT1992, IWLS::CoudertFM1993, IFIP::DrechslerB1993, EDTC::DrechslerB1995, ICANNGA::DrechslerBG1995, DAC::DrechslerSTBP1994, EDAC::DrechslerTB1994, WG::GergovM1992, IEEETCAD::GergovM1994, ISFTC::KriegerBS1993, ECDA::KebschullR1993, ECDA::KebschullSR1992, BSTJ::Lee1959, BOOK::Leeuven1990, DAC::LaiS1992, BOOK::Meinel1989, DAC::Minato1993, TR::Paterson1986, BOOK::PellerinH1991, TR::Razborov1986, IEEETC::Reddy1972, IFIP::Rollwage1993, ICCAD::Rudell1993, BOOK::Sasao1993, ECDA::Saul1992, IEEETC::SasaoB1990, EUROASIC::SchubertKR1992, IFIP::SarabiP1993, IEEETC::SalujaR1975, IPL::SielingW1993, TCS::SielingW1995, IC::Wegener1984:129, BOOK::Wegener1987, MISC::WerchnerHDB1994, EDAC::WanP1992, BOOK::Xilinix1988} } @Article{Palsberg95, refkey={C1680; PN2520}, title={Efficient Inference of Object Types}, author={Jens Palsberg}, pages={198--209}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={Abadi and Cardelli have recently investigated a calculus of objects (Abadi and Cardelli, 1994). The calculus supports a key feature of object-oriented languages: an object can be emulated by another object that has more refined methods. Abadi and Cardelli presented four first-order type systems for the calculus. The simplest one is based on finite types and no subtyping, and the most powerful one has both recursive types and subtyping. Open until now is the question of type inference, and in the presence of subtyping ``the absence of minimum typings poses practical problems for type inference'' (Abadi and Cardelli, 1994). \par In this paper we give an $O(n^3)$ algorithm for each of the four type inference problems and we prove that all the problems are P-complete. We also indicate how to modify the algorithms to handle functions and records.}, references={LICS::AbadiC1994:332, MISC::AbadiC1993, ESOP::AbadiC1994, TACS::AbadiC1994:296, CFPLCA::AikenW1993, MISC::Benke1994, HTCS::BoppanaS1990, JLOGP::DworkKM1984, MFPS::SmithET1995, ESOP::FuhM1988, TAPSOFT::FuhM1989, TR::Henglein1988, ICCI::Henglein1990, POPL::HoangM1995, TCS::Italiano1986, HTCS::KarpR1990, JCSS::KozenPS1994, FOCS::KozenPS1992:363, MISC::Nygaard1987, POPL::Mitchell1984, LICS::MitchellHF1993:26, GTCCS::PoutreL1988, POPL::Remy1989, LICS::Tiuryn1992:308, LICS::Wand1989:92} } @Article{PelegW95, refkey={C1658; PN2519}, title={The Availability of Quorum Systems}, author={David Peleg and Avishai Wool}, pages={210--223}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={A {\em quorum system\/} is a collection of sets (quorums) every two of which intersect. Quorum systems have been used for many applications in the area of distributed systems, including mutual exclusion, data replication and dissemination of information \par In this paper we study the failure probabilities of quorum systems and in particular of non-dominated coteries (NDC). We characterize NDC's in terms of the failure probability, and prove that any NDC has availability that falls between that of a singleton and a majority consensus. We show conditions for weighted voting schemes to provide asymptotically high availability, and analyze the availability of several other known quorum systems.}, references={ACMTCS::AhamadA1991, ACMTCS::AgrawalA1991, BOOK::AlonS1992, DISCM::Beck1978, ACMTCS::BarbaraG1986, IEEETC::BarbaraG1987, TR::BiochI1993, BOOK::Bollobas1986, BOOK::BarlowP1975, JAPPP::BorlandPT1989, ICDE::CheungAA1990, ANNMAS::Chernoff1952, THESIS::Cohen1993, MISC::Condorcet1785, ACMCS::DavidsonGS1985:341, IPL::DiksKKMP1994, QUAJM::ErdosKR1961, CMSJB::ErdosL1975, NORMT::Erdos1963, COMMMP::FortuinKG1971, THESIS::Fu1990, JACM::Garcia-MolinaB1985:841, SOSP::Gifford1979, THESIS::Herlihy1984, WADS::HolzmanMP1995, IEEETPDS::IbarakiK1993, ICDCS::IbarakiNK1992, BOOK::Karlin1968, IPL::KumarC1991, IEEETC::KakugawaFYA1993, PICDCS::KumarRS1993, IEEETC::Kumar1991, SCCGTC::Lovasz1973, ACMTCS::Maekawa1985, BOOK::MarshallO1979, TR::MarcusP1992, TR::MarcusP1992, ALGOR::MullenderV1988, THESIS::Neilsen1992, IEEETPDS::NeilsenM1992, FOCS::NaorW1994:214, TR::NaorW1995, BOOK::Owen1982, TR::PelegW1993, PODC::PelegW1995, JCSS::Raghavan1988, BOOK::Raynal1986, ICDE::RangarajanST1992, WDAG::RangarajanT1991, IEEETPDS::SpasojevicB1994, ACMTDS::Thomas1979, JCOMTB::Tuza1985, ICPDIS::YanG1994} } @Article{KinberS95, refkey={C1656; PN2517}, title={Language Learning from Texts: Mindchanges, Limited Memory, and Monotonicity}, author={Efim Kinber and Frank Stephan}, pages={224--241}, journal=iandcomp, month=dec, year=1995, volume=123, number=2, abstract={The paper explores language learning in the limit under various constraints on the number of mindchanges, memory, and monotonicity. We define language learning with limited (long term) memory and prove that learning with limited memory is exactly the same as learning via set driven machines (when the order of the input string is not taken into account). Further we show that every language learnable via a set driven machine is learnable via a conservative machine (making only justifiable mindchanges). We get a variety of separation results for learning with bounded number of mindchanges or limited memory under restrictions on monotonicity. A surprising result is that there are families of languages that can be monotonically learned with at most one mindchange, but can neither be weak-monotonically nor conservatively learned. Many separation results have a variant: If a criterion $\mathcal{A}$ can be separated from $\mathcal{B}$, then often it is possible to find a family $\mathcal{L}$ of languages such that $\mathcal{L}$ is $\mathcal{A}$ and $\mathcal{B}$ learnable, but while it is possible to restrict the number of mindchanges or long term memory on criterion $\mathcal{A}$, this is impossible for $\mathcal{B}$.}, references={Angluin1980:117, ACMCS::AngluinS1983:237, MISC::AngluinS1987, BlumB1975:125, COLT::FreivaldsKS1993, Gold1967:447, WALT::JainS1994, NGC::Jantke1991, WALT::Kapur1992, WALT::Kinber1994, COLT::LangeZ1992, IJFCS::LangeZ1993, MISC::LangeZ1994, TCS::LangeZK1996:365, WALT::Mukouchi1992, BOOK::Odifreddi1989, BOOK::OshersonSW1986, THESIS::Schafer1984, BOOK::Soare1987, BOOK::WexlerC1980, MISC::Zeugmann1993} } January 10, 1996 Volume 124, Number 1 @Article{FortnowR96, refkey={C1532; PN2527}, title={{PP} Is Closed under Truth-Table Reductions}, author={Lance Fortnow and Nick Reingold}, pages={1--6}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={Beigel, Reingold and Spielman (\emph{J.\ Comput.\ System Sci.}\ \textbf{50}, 191--202 (1995)) showed that PP is closed under intersection and a variety of special cases of polynomial-time truth-table closure. We extend their techniques to show that PP is closed under general polynomial-time truth-table reductions. We also show that PP is closed under constant-round truth-table reductions.}, references={CC::BabaiF1991, JCSS::BeigelRS1995, STOC::Cook1971, JCSS::FennerFK1994, SICOMP::Gill1977, SICOMP::Venkateswaran1992} } @Article{Gruchalski96, refkey={C1604; PN2528}, title={Computability on {dI}-Domains}, author={Andreas Gruchalski}, pages={7--19}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={In this paper we investigate a subset of the class of Scott-computable stable functions called Berry-computable. Furthermore we introduce a corresponding notion of an effectively given dI-domain. We obtain the result that the category with these domains as objects and Berry-computable functions as morphisms has all the important attributes of recursive domains and Scott-computable continuous functions, e.g., Cartesian closedness. Moreover, we investigate the relationship between stable functions and sequential algorithms. We show that any Berry-computable function can be computed in a sequential way by a relative algorithm. Additionally, if the codomain of the considered stable function is an atomic dI-domain, we obtain the result that the reverse holds as well}, references={IC::Asperti1990, ICALP::Berry1978, TCS::BucciarelliE1993, IC::BucciarelliE1994, THESIS::Bucciarelli1993, BOOK::Curien1993, BOOK::GirardLT1989, TCS::Girard1986, MISC::Gruchalski1993, TR::KahnP1978, MISC::Plotkin1983, BOOK::Rogers1967, BOOK::Scott1970, TCS::WeihrauchS1983:131, SCA::DC1971, TCS::Smyth1977, BOOK::Stoy1977, MISC::WeihrauchD1980, BOOK::Weihrauch1987, BOOK::Zhang1991} } @Article{CeceFI96, refkey={C1630; PN2524}, title={Unreliable Channels Are Easier to Verify Than Perfect Channels}, author={G{\'e}rard C{\'e}c{\'e} and Alain Finkel and S. Purushothaman Iyer}, pages={20--31}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={We consider the problem of verifying correctness of finite state machines that communicate with each other over unbounded FIFO channels that are unreliable. Various problems of interest in verification of FIFO channels that can lose messages have been considered by Finkel~(1994), and by Abdulla and Jonsson~(1993, 1994). We consider, in this paper, other possible unreliable behaviors of communication channels, viz. (a) duplication and (b) insertion errors. Furthermore, we also consider various combinations of duplication, insertion and lossiness errors. Finite state machines that communicate over unbounded FIFO buffers is a model of computation that forms the backbone of ISO standard protocol specification languages Estelle and SDL. While an assumption of a perfect communication medium is reasonable at the higher levels of the OSI protocol stack, the lower levels have to deal with an unreliable communication medium; hence our motivation for the present work. The verification problems that are of interest are {\em reachability}, {\em unboundedness}, {\em deadlock}, and {\em model-checking against CTL*}. All of these problems are undecidable for machines communicating over reliable unbounded FIFO channels. So, it is perhaps surprising that some of these problems become decidable when unreliable channels are modeled. The contributions of this paper are: (a)~An investigation of solutions to these problems for machines with insertion errors, duplication errors, or a combination of duplication, insertion and lossiness errors, and (b)~A comparison of the relative expressive power of the various errors.}, references={LICS::AbdullaJ1993, ICALP::AbdullaJ1994, CACM::BartlettSW1969, BOOK::Berstel1979, COMPNET::Bochmann1978, JACM::BrandZ1983, MISC::CCITT1988, BOOK::DiazAC1989, JACM::EmersonH1986, DC::Finkel1994, TCS::GlabbeekV1993, CAI::GoudaGLR1987, PLMS::Higman1952, BOOK::Lothaire1983, PSTV::Pachl1987, TOPLAS::PengP1991, PJMATH::Tarski1955} } @Article{KesnerPT96, refkey={C1639; PN2530}, title={A Typed Pattern Calculus}, author={Delia Kesner and Laurence Puel and Val Tannen}, pages={32--61}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={The theory of pgogramming with pattern-matching function definitions has been studied mainly in the framework of first-order rewrite systems. We present a typed functional calculus that emphasizes the strong connection between the structures of whole pattern definitions and their types. In this calculus, type-checking guarantees the absence of runtime errors caused by non-exhaustive pattern-matching definitions. Its operational semantics is deterministic in a natural way, without the imposition of ad hoc solutions such as clause order or ``best fit''. In the spirit of the Curry-Howard isomorphism, we design the calculus as a computational interpretation of the Gentzen sequent proofs for the intuitionistic propositional logic. We prove the basic properties connecting typing and evaluation: subject reduction and strong normalization. We believe that this calculus offers a rational reconstruction of the pattern-matching features found in successful functional languages.}, references={TR::AbadiCCL1990, TCS::Abramsky1993, ICALP::TannenS1991:60, LISPC::BurstallMS1980, ICALP::Colson1989, WTPP::Coquand1992, BOOK::FieldH1988, TCS::Gallier1993, BOOK::GirardLT1989, THESIS::Howard1992, SIGPLAN::HudakPWa1992, MISC::HuetL1991, STACS::Kahn1987, CLFP::JategaonkarM1988, BOOK::Jones1987, MISC::Lafont1989, MISC::Leroy1994, BOOK::MilnerTH1990, MISC::Oostrom1991, TR::Plotkin1981, JSYMC::PuelS1993, POPL::Remy1989, FPLCA::Turner1985, MISC::Wadler1990} } @Article{Haack96, refkey={C1664; PN2529}, title={A Decomposition Theorem for Domains}, author={Christian Haack}, pages={62--67}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={A domain constructor that generalizes the product is defined. It is shown that with this constructor exactly the prime-algebraic coherent Scott-domains and the empty set can be generated from two-chains and boolean flat domains.}, references={MISC::AbramskyJ1994, TCS::BunemanJO1991:23, BOOK::GierzHKLMS1980, TCS::Girard1987:1, THESIS::Haack1993, IC::Huth1995:10, MFPS::JungLP1992:235, TCS::NielsenPW1981:85, THESIS::Puhlmann1990, MISC::Winskel1987:325, MFPS::Zhang1991:426} } @Article{AndersonY96, refkey={C1766; PN2526}, title={Time/Contention Trade-offs for Multiprocessor Synchronization}, author={James H. Anderson and Jae-Heon Yang}, pages={68--84}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={We establish trade-offs between time complexity and write- and access-contention for solutions to the mutual exclusion problem. The {\em write-contention\/} ({\em access-contention\/}) of a concurrent program is the number of processes that may be simultaneously enabled to write (access by reading and/or writing) the same shared variable. Our notion of time complexity distinguishes between local and remote accesses of shared memory. We show that, for any $N$-process mutual exclusion algorithm, if write-contention is $w$, and if at most $v$ remote variables can be accessed by a single atomic operation, then there exists an execution involving only one process in which that process executes $\Omega(\log_{vw} N)$ remote operations for entry into its critical section. We further show that, among these operations, $\Omega(\sqrt{\log_{vw} N})$ distinct remote variables are accessed. For algorithms with access-contention $c$, we show that the latter bound can be improved to $\Omega(\log_{vc} N)$. The last two of these bounds imply that a trade-off between contention and time complexity exists even if coherent caching techniques are employed. In most shared-memory multiprocessors, an atomic operation may access only a constant number of remote variables. In fact, most commonly-available synchronization primitives (e.g., read, write, test-and-set, load-and-store, compare-and-swap, and fetch-and-add) access only one remote variable. In this case, the first and the last of our bounds are asymptotically tight. Our results have a number of important implications regarding specific concurrent programming problems. For example, the time bounds that we establish apply not only to the mutual exclusion problem, but also to a class of decision problems that includes the leader-election problem. Also, because the execution that establishes these bounds involves only one process, it follows that ``fast mutual exclusion'' requires arbitrarily high write-contention. Although such conclusions are interesting in their own right, we believe that the most important contribution of our work is to identify a time complexity measure for asynchronous concurrent programs that strikes a balance between being conceptually simple and having a tangible connection to real performance.}, references={RTSS::AlurT1992, ACTAI::Anderson1993, IEEETPDS::Anderson1990, IC::BurnsL1993, DC::ChandyM1986, CACM::Dijkstra1965, STOC::DworkHW1993, IEEEC::GraunkeT1990, TOPLAS::Herlihy1991, SPAA::HerlihyLS1992, FOCS::HerlihySW1991, ACMTCS::Lamport1987, ACMTCS::LimA1993, RTSS::LynchS1992, ACMTCS::Mellor-CrummeyS1991, PODC::MerrittT1991, IEEETC::PfisterN1985, MISC::Turan1941, PODC::YangA1993}, preliminary={STOC::YangA1994:224} } @Article{KosiuczenkoM96, refkey={C1642; PN2531}, title={On the Power of Higher-Order Algebraic Specification Methods}, author={P. Kosiuczenko and K. Meinke}, pages={85--101}, journal=iandcomp, month={10~} # jan, year=1996, volume=124, number=1, abstract={Soundness and adequacy theorems are presented for the expressive power of higher-order initial algebra specifications with respect to the arithmetical and analytical hierarchies. These results demonstrate that higher-order initial algebra semantics substantially extends the power of both first-order initial and first-order final algebra semantics. It thus provides a unifying framework for all three different approaches to the semantics of algebraic specifications.}, references={IC::BergstraT1982, SICOMP::BergstraT1983, TCS::BergstraT1987, BOOK::EhrigM1985, SIGPLAN::GoguenM1982, MISC::GoguenTWW1975, HDA::HeeringMMN1994, BOOK::Hinman1978, RMS::Malcev1961, TCS::Meinke1992, MISC::Meinke1993, ACTAI::Meinke1994, TR::Meinke1995, MISC::MeinkeT1993, MISC::Moller1987, TAMS::Rabin1960, BOOK::Rogers1967, HTCS::Wirsing1990} } February 1, 1996 Volume 124, Number 2 @Article{Howe96, refkey={C1346; PN2518}, title={Proving Congruence of Bisimulation in Functional Programming Languages}, author={Douglas J. Howe}, pages={103--112}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={We give a method for proving congruence of bisimulation-like equivalences in functional programming languages. The method applies to languages that can be presented as a set of expressions together with an evaluation relation. We use this method to show that some generalizations of Abramsky's applicative bisimulation are congruences whenever evaluation can be specified by a certain natural form of structured operational semantics. One of the generalizations handles nondeterminism and diverging computations.}, references={MISC::Abramsky1988, MISC::Aczel1978, TR::Berry1981, IC::Bloom1990, IC::GrooteV1992:202, LICS::Howe1989, LICS::Howe1991, THESIS::Jagadeesan1991, STACS::Kahn1987, BOOK::Klop1980, SPPS::Ong1992, TR::Plotkin1981, GFPW::Sands1991, IC::Sangiorgi1994, THESIS::Talcott1985} } @Article{Ho96, refkey={C1644; PN2532}, title={Beyond Recursive Real Functions}, author={Chun-Kuen Ho}, pages={113--126}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={All recursive real functions are continuous; in fact all the $B$-recursive real functions are continuous for any oracle $B$, simply because Turing Machines computing them are finite objects. But simple discontinuous functions like step functions have to be in some sense ``easy'' if they have recursive values and break points, although they are not computable by the usual definition. It seems unfair to label them noncomputable in the entire region just because of a few break points. In this paper, we investigate the properties of broader classes of \emph{almost everywhere recursive}, \emph{weakly almost everywhere recursive} and \emph{recursively approximable} real-valued functions, which capture these ``easy'' step functions and many other nonrecursive functions. Recursive versions of the classical Lusin and Egoroff Theorems are proved. We also characterize the property of the limit of a recursive sequence of functions and show that different notions of convergence (uniform, pointwise or in measure) will result in different characterizations of the limiting function.}, references={BOOK::Bishop1967, BOOK::BishopB1985, MAMS::BishopC1972, PJMATH::Bridges1972, PJMATH::Chan1972, MISC::Grzegorczyk1959, BOOK::Halmos1974, BOOK::HewittS1965, TR::Ho1993, BOOK::Ko1991, COMPREN::KreiselL1957, MMATHJ::Myhill1971, TAMS::Nuber1972, BOOK::Pour-ElR1989, book::Sanin1968, BOOK::Royden1988, BOOK::Rudin1986, BOOK::Soare1987} } @Article{Ben-EliyahuM96, refkey={C1160; PN2525}, title={A Temporal Logic for Proving Properties of Topologically General Executions}, author={Rachel Ben-Eliyahu and Menachem Magidor}, pages={127--144}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={We present a generalization of the temporal propositional logic of linear time which is useful for stating and proving properties of the generic execution sequence of a parallel program or a non-deterministic program. The formal system we present is exactly that same as the third of three logics presented in (Daniel Lehmann and Saharon Shelah. Reasoning with time and chance. \emph{Information and Control}, 53(3):165-198, June 1982.), but we give it a different semantics. The models are tree models of arbitrary size similar to those used in branching time temporal logic. The formulation we use allows us to state properties of ``co-meagre'' famil of paths, where the term ``co-meagre'' refers to a set whose complement is of the first category in Baire's classification, looking at the set of paths in the model as a metric space. Our system is decidable, sound and complete for models of arbitrary size, but it has a finite model property, namely every sentence having a model has a finite model.}, references={TCS::ArnoldN1980, BakkerZ1982:70, POPL::GabbayPSS1980, TCS::KatzP1990, JACM::Lamport1986:313, POPL::LehmannR1981, LehmannS1982:165, STOC::Pnueli1983, FOCS::Vardi1985} } @Article{FraserIM96, refkey={C1660; PN2533}, title={Maximal Common Subsequences and Minimal Common Supersequences}, author={Campbell B. Fraser and Robert W. Irving and Martin Middendorf}, pages={145--153}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={The problems of finding a longest common subsequence and a shortest common supersequence of a set of strings are well-known. They can be solved in polynomial time for two strings (in fact the problems are dual in this case), or for any fixed number of strings, by dynamic programming. But both problems are NP-hard in general for an arbitrary number $k$ of strings. Here we study the related problems of finding a shortest maximal common subsequence and a longest minimal common supersequence. We describe dynamic programming algorithms for the case of two strings (for which case the problems are no longer dual), which can be extended to any fixed number of strings. We also show that both problems are NP-hard in general for $k$ strings, although the latter problem, unlike shortest common supersequence, is solvable in polynomial time for strings of length 2. Finally, we prove a strong negative approximability result for the shortest maximal common subsequence problem.}, references={FOCS::AroraLMSS1992:14, BOOK::GareyJ1979, IPL::Halldorsson1993:169, JACM::Maier1978:322, KIBER::Timkovskii1989:1, MISC::JiangL1992, ALGOR::ApostolicoG1987:316, CACM::Hirschberg1975:341, JACM::Hirschberg1977:664, CACM::HuntS1977:350, ALGOR::Myers1986:251, JCSS::PapadimitriouY1991:425, IC::Ukkonen1985:100, IPL::WuMMM1990:317, IPL::Irving1991:197, SIDMA::YannakakisG1980:364, TCS::RaihaU1981:187, THESIS::Middendorf1992} } @Article{Rabinovich96, refkey={C1694; PN2535}, title={On Schematological Equivalence of Dataflow Networks}, author={Alexander Rabinovich}, pages={154--167}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={We consider the problem of determining when two dataflow networks with uninterpreted nodes always have the same input-output behavior. \par We define a set of behavior-preserving transformations on networks and show that this set is ``schematologically complete", i.e., networks have the same input-output behavior under all interpretations if and only if they can be transformed into isomorphic networks. \par As a by product, we obtain a polynomial algorithm for deciding schematological equivalence of dataflow networks.}, references={MISC::BrockA1981, BOOK::CormenR1991, ICALP::CourcelleKV1974:200, TR::DennisF1973, BOOK::Faustini1982, BOOK::Greibach1975, POPL::Jonsson1989, IP::Kahn1974, PODC::LynchT1987, Parrow1993, ICCT::Rabinovich1992, REX::RabinovichT1988, LICS::Stark1992 } } @Article{Yen96, refkey={C1527; PN2536}, title={On the Regularity of {Petri} Net Languages}, author={Hsu-Chun Yen}, pages={168--181}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={Petri nets are known to be useful for modeling concurrent systems. Once modeled by a Petri net, the behavior of a concurrent system can be characterized by the set of all executable transition sequences, which in turn can be viewed as a language over an alphabet of symbols corresponding to the transitions of the underlying Petri net. In this paper, we study the language issue of Petri nets from a computational complexity viewpoint. We analyze the complexity of the \emph{regularity problem} (i.e., the problem of determining whether a given Petri net defines an irregular language or not) for a variety of classes of Petri nets, including \emph{conflict-free, trap-circuit, normal, sinkless, extended trap-circuit, BPP}, and \emph{general} Petri nets. (Extended trap-circuit Petri nets are trap-circuit Petri nets augmented with a specific type of \emph{circuits}.) As it turns out, the complexities for these Petri net classes range from NL (nondeterministic logspace), PTIME (polynomial time), NP (nondeterministic polynomial time), to EXPSPACE (exponential space). In the process of deriving the complexity results, we develop a \emph{decomposition approach} which, we feel, is interesting in its own right, and might have other applications to the analysis of Petri nets as well. As a by-product, an NP upper bound of the reachability problem for the class of extended trap-circuit Petri nets (which properly contains that of trap-circuit (and hence, conflict-free) and BPP-nets, and is incomparable with that of normal and sinkless Petri nets) is derived.}, references={SCA::AgerwalaF1973, ICCT::ChristensenHM1993, IPL::Esparza1992, TR::Esparza1994, JCSS::GinzburgY1980, BOOK::HopcroftU1979, JCSS::HowellR1988, IPL::HowellRY1987, JCSS::HowellRY1993, IC::Huynh1983, MISC::IchikawaH1987, TCS::JantzenP1994, TCS::JonesLL1977, DOKAN::Khachian1979, OSR::Kosaraju1973, JACM::LandweberR1978, MATOR::Lenstra1983, TR::Lipton1976, PIEEE::Murata1989, BOOK::Peterson1981, BOOK::Reisig1985, IPL::Schwer1986, JCSS::ValkV1981, TCS::Yamasaki1984, IPL::Yen1991, IC::Yen1992} } @Article{Edalat96, refkey={C1657, PN2534}, title={Power Domains and Iterated Function Systems}, author={Abbas Edalat}, pages={182--197}, journal=iandcomp, month={1~} # feb, year=1996, volume=124, number=2, abstract={We introduce the notion of weakly hyperbolic iterated function system (IFS) on a compact metric space, which generalises that of hyperbolic IFS. Based on a domain-theoretic model, which uses the Plotkin power domain and the probabilistic power domain respectively, we prove the existence and uniqueness of the attractor of a weakly hyperbolic IFS and the invariant measure of a weakly hyperbolic IFS with probabilities, extending the classic results of Hutchinson for hyperbolic IFSs in this more general setting. We also present finite algorithms to obtain discrete and digitised approximations to the attractor and the invariant measure, extending the corresponding algorithms for hyperbolic IFSs. We then prove the existence and uniqueness of the invariant distribution of a weakly hyperbolic recurrent IFS and obtain an algorithm to generate the invariant distribution on the digitised screen. The generalised Riemann integral is used to provide a formula for the expected value of almost everywhere continuous functions with respect to this distribution. For hyperbolic recurrent IFSs and Lipschitz maps, one can estimate the integral up to any threshold of accuracy.}, references={LICS::Edalat1994, TCS::Edalat1995:163, Edalat1995, LICS::JonesP1989, TCS::Saheb-Djahromi1980:19} } February 25, 1996 Volume 125, Number 1 @Article{CreignouH96, refkey={C1618; PN2538}, title={Complexity of Generalized Satisfiability Counting Problems}, author={Nadia Creignou and Miki Hermann}, pages={1--12}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={The class of generalized satisfiability problems, introduced in 1978 by Schaefer, presents a uniform way of studying the complexity of satisfiability problems with special conditions. The complexity of each decision and counting problem in this class depends on the involved logical relations. In 1979, Valiant defined the class~\#P, the class of functions definable as the number of accepting computations of a polynomial-time nondeterministic Turing machine. Clearly, all satisfiability counting problems belong to this class~\#P\@. We prove a Dichotomy Theorem for generalized satisfiability counting problems. That is, if all logical relations involved in a generalized satisfiability counting problem are affine then the number of satisfying assignments of this problem can be computed in polynomial time, otherwise this function is \#P-complete. This gives us a comparison between decision and counting generalized satisfiability problems. We can determine exactly the polynomial satisfiability decision problems whose number of solutions can be computed in polynomial time and also the polynomial satisfiability decision problems whose counting counterparts are already \#P-complete. Moreover, taking advantage of a similar dichotomy result proved in 1978 by Schaefer for generalized satisfiability decision problems, we get as a corollary the implication that the counting counterpart of each NP-complete generalized satisfiability decision problem is \#P-complete.}, references={TR::CreignouH1993, BOOK::ChangK1990, STOC::Cook1971, TCS::Dubois1991, TCS::FortuneHW1980, STOC::FederV1993, SIGACT::Galil1974, BOOK::GareyJ1979, CAD::HermannK1994, JCOMTB::HellN1990, BEATCS::HemachandraO1992, BOOK::Hodges1993, JSYML::Horn1951, HTCS::Johnson1990, BOOK::Kozen1992, SIAJADM::Linial1986, JSYML::McKinsey1943, BOOK::Papadimitriou1994, SICOMP::ProvanB1983, IJCAI::Roth1993, STOC::Schaefer1978, THESIS::Simon1975, ICALP::Simon1977, FOCS::Toda1989, TCS::Valiant1979, SICOMP::Valiant1979} } @Article{JuedesL96, refkey={C1724; PN2537}, title={Completeness and Weak Completeness under Polynomial-Size Circuits}, author={David W. Juedes and Jack H. Lutz}, pages={13--31}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={This paper investigates the distribution and nonuniform complexity of problems that are complete or weakly complete for ESPACE under nonuniform reductions that are computed by polynomial-size circuits (P/Poly-Turing reductions and P/Poly-many-one reductions). A tight, exponential lower bound on the space-bounded Kolmogorov complexities of weakly P/Poly-Turing-complete problems is established. A Small Span Theorem for P/Poly-Turing reductions in ESPACE is proven and used to show that \emph{every} P/Poly-Turing degree---including the complete degree---has measure 0 in ESPACE. (In contrast, it is known that almost every element of ESPACE is weakly P-many-one complete.) Every weakly P/Poly-many-one-complete problem is shown to have a dense, exponential, nonuniform complexity core. More importantly, the P/Poly-many-one-complete problems are shown to be \emph{unusually simple} elements of ESPACE, in the sense that they obey nontrivial \emph{upper} bounds on nonuniform complexity (size of nonuniform complexity cores and space-bounded Kolmogorov complexity) that are violated by almost every element of ESPACE.}, references={JSYML::AjtaiF1990:113, SICOMP::AllenderR1988:1193, JCSS::Allender1989:101, IC::AllenderW1990:160, MFCS::Ambos-SpiesNT1994, ISAC::Ambos-SpiesTX1994, ACTAI::BalcazarB1986:679, MST::BalcazarS1985:1, SICOMP::BermanH1977:305, BOOK::Billingsley1986, JACM::BookD1987:718, SCTC::BookDR1988:236, JACM::Chaitin1966:547, STOC::Cook1971:151, THESIS::Du1985, TCS::DuB1989:239, JACM::EvenSY1985:205, ICALP::FennerLM1995:393, BOOK::Halmos1950, FOCS::Hartmanis1983:439, TCS::HartmanisY1984:17, BOOK::Huynh1986:184, IPL::Huynh1987:171, THESIS::Juedes1994, CC::Juedes1995:267, SICOMP::JuedesL1995:279, TCS::JuedesL1995:149, IC::Kannan1982:40, MISC::Karp1972:85, TCS::Ko1986:9, PROIT::Kolmogorov1965:1, PROIT::Levin1973:265, IC::Levin1984:15, THESIS::Lindner1993, THESIS::Longpre1986, SICOMP::Lutz1990:1100, TCS::Lutz1991:127, JCSS::Lutz1992:220, SCTC::Lutz1994, MISC::Lutz00, SICOMP::LutzM1994:762, STACS::LutzM1994, JACM::Lynch1975:341, MISC::Martin-Lof1971:225, THESIS::Mayordomo1994, TCS::Orponen1986:121, IC::OrponenS1986:54, FOCS::Pippenger1979:307, STOC::RazborovR1994:204, FOCS::ReganSC1995, MST::RussoO1987:129, STOC::Sipser1983:330, JACM::SkyumV1985:484, IC::Solomonoff1964:1, MISC::Ye1990} } @Article{GiammarresiRST96, refkey={C1614; PN2553}, title={Monadic Second-Order Logic over Rectangular Pictures and Recognizability by Tiling Systems}, author={Dora Giammarresi and Antonio Restivo and Sebastian Seibert and Wolfgang Thomas}, pages={32--45}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={It is shown that a set of pictures (rectangular arrays of symbols) is recognized by a finite tiling system iff it is definable in existential monadic second-order logic. As a consequence, finite tiling systems constitute a notion of recognizability over two-dimensional inputs which at the same time generalizes finite-state recognizability over strings and also matches a natural logic. The proof is based on the Ehrenfeucht-Fra{\"\i}ss\'e technique for first-order logic and an implementation of ``threshold counting'' within tiling systems.}, references={FOCS::BlumH1967, IC::BossutDW1995:251, IC::Courcelle1990:12, BOOK::Eilenberg1974, BOOK::EbbinghausFT1994, ZMLGM::Fagin1975, SCTC::FaginSV1993, MISC::GiammarresiR1991, FUNDI::GiammarresiR1992, MISC::Han1965, BOOK::HopcroftU1979, INFOS::InoueN1977, TIECEJ::InoueN1977, IMYCS::InoueT1990, ICPIP::InoueT1992, BBMS::PotthoffST1994, ICALP::Thomas1991:441}, preliminary={stacs::GiammarresiRST1994:365} } @Article{LafontS96, refkey={C1754; PN2547}, title={The Undecidability of Second Order Multiplicative Linear Logic}, author={Yves Lafont and Andre Scedrov}, pages={46--51}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={The multiplicative fragment of second order propositional linear logic is shown to be undecidable.}, references={THESIS::Amiot1994, TCS::Girard1987, MISC::Girard1995, APAL::Kanovich1994:195, MISC::Kanovich1995, JSYML::Lafont1996:541, CANMB::Lambek1961, APAL::LincolnMSS1992, TCS::LincolnS1994, LICS::LincolnSS1995, LICS::LincolnS1994, TCS::LincolnW1994, ANM::Minsky1961, MISC::Scedrov1993, MISC::Scedrov1995} } @Article{Bar-IlanP96, refkey={C1534; PN2551}, title={Scheduling Jobs Using Common Resources}, author={Judit Bar-Ilan and David Peleg}, pages={52--61}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={This paper examines the problem of distributed resource allocation in different models of computation and communication in distributed systems, and presents a number of time optimal (randomized and deterministic) allocation algorithms. We consider the dining/drinking philosophers problem as presented in [B. Awerbuch and M. Saks, \emph{in} ``FOCS,'', pp.~65--74. IEEE, New York, 1990]. In the algorithm presented in that paper, the delay from the creation of a job to the time it started executing depends quadratically on the number of jobs conflicting with it. In this paper we improve this result by presenting an algorithm for which the dependence becomes linear, which is optimal.}, references={STOC::AwerbuchCS1994, FOCS::AwerbuchS1990, JACM::Awerbuch1985, TOPLAS::ChandyM1984, STOC::ChoyS1992, ACTAI::Dijkstra1971, TR::EvenR1988, TOPLAS::GallagerHS1983, CACM::Lamport1978:558, JCSS::Lynch1981, POPL::LehmannR1981, PODC::StyerP1988} } @Article{KupfermanG96, refkey={C1605; PN2548}, title={Branching-Time Temporal Logic and Tree Automata}, author={Orna Kupferman and Orna Grumberg}, pages={62--69}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={In temporal-logic model checking, we verify the correctness of a program with respect to a desired behavior by checking whether a structure that models the program satisfies a temporal logic formula that specifies this behavior. The close connection between linear-time temporal logics and the theory of automata on infinite words has been an active area of research. In particular, automata-theoretic techniques have proven to be an effective approach to linear-time model checking. On the other hand, for branching-time temporal logics, current automata-theoretic techniques involve an exponential blow up, making them essentially useless for model-checking. In this paper we present an automata-theoretic framework for branching-time model checking. We introduce \emph{simultaneous trees} and associate with every structure a simultaneous tree that enables an automaton to visit different nodes on the same path of the structure simultaneously. With every formula $\psi$ we associate an automaton that accepts exactly these simultaneous trees that originate from structures that satisfy $\psi$. This enables to use the automaton for model checking which is reduced to the membership problem. We demonstrate our framework with the branching-time temporal logic CTL and show that it yields a linear automata-based model-checking algorithm, matching the known bound. This is the first time that a model-checking algorithm for a branching-time temporal logic is placed in the automata-theoretic framework.}, references={LNCS::BernholtzG1993:262, TCS::Pnueli1981:45, IC::VardiW1994:1, JCSS::VardiW1986:183, LNCS::JardJ1989:189, FMSD::CourcoubetisVWY1992, TAMS::Rabin1969:1, LICS::VardiW1986, TOPLAS::ClarkeES1986, ICALP::MullerSS1986, CAV::BernholtzVW1994, LNCS::WolperG1993, CAV::EmersonJS1993} } @Article{BookW96, refkey={C1677; PN2545}, title={On Random Hard Sets for {NP}}, author={Ronald V. Book and Osamu Watanabe}, pages={70--76}, journal=iandcomp, month={25~} # feb, year=1996, volume=125, number=1, abstract={The problem of whether NP has a random hard set (that is, a hard set in RAND) is investigated. We show that for every recursive oracle~$A$ such that $\mathrm{P}^A \ne \mathrm{NP}^A$, \ $\mathrm{NP}^A$ has no hard set in RAND\@. On the other hand, we also show that for almost every oracle~$A$, \ $\mathrm{P}^A \ne \mathrm{NP}^A$ and $\mathrm{NP}^A$ has a hard set in RAND\@.}, references={BOOK::BalcazarDG1988, BOOK::BalcazarDG1990, SICOMP::BennettG1981, MST::BookLW1994, JACM::Chaitin1975:329, IC::Gacs1986, TCS::JuedesLL1994, PINFT::Levin1974, BOOK::LiV1993, IC::Martin-Lof1966:602, JCSS::Schnorr1973, THESIS::Lambalgen1987} } March 15, 1996 Volume 125, Number 2 Symposium Issue on Theoretical Aspects of Computer Software 1994 Guest Editor: Masami Hagiya @Article{Hagiya96, refkey={C1847; PN2534}, title={Preface}, author={Masami Hagiya}, pages={77}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2 } @Article{AbadiC96, refkey={C1848, PN2540}, title={A Theory of Primitive Objects: Untyped and First-Order Systems}, author={Mart{\'\i}n Abadi and Luca Cardelli}, pages={78--102}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2, abstract={We introduce simple object calculi that support method override and object subsumption. We give an untyped calculus, typing rules, and equational rules. We illustrate the expressiveness of our calculi and the pitfalls that we avoid}, references={JFP::Abadi1994, LICS::AbadiC1994, TOPLAS::AbadiCPP1991, POPL::AmadioC1991, JFP::Bruce1994, IC::Cardelli1988, POPL::Kamin1988, POPL::Mitchell1990, LICS::MitchellHF1993, LICS::Palsberg1994, JFP::PierceT1994, LICS::Wand1987}, preliminary={TACS::AbadiC1994} } @Article{BarbaneraB96, refkey={C1829; PN2541}, title={A Symmetric Lambda Calculus for Classical Program Extraction}, author={Franco Barbanera and Stefano Berardi}, pages={103--117}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2, abstract={We introduce a $\lambda$-calculus with symmetric reduction rules and ``classical'' types, i.e., types corresponding to formulas of classical propositional logic. The strong normalization property is proved to hold for such a calculus, as well as for its extension to a system equivalent to Peano arithmetic. A theorem on the shape of terms in normal form is also proved, making it possible to get recursive functions out of proofs of $\Pi^0_2$ formulas, i.e., those corresponding to program specifications.}, references={JSYML::Coquand1995:325, POPL::Griffin1990, JSYML::Kreisel1958, JSYML::Tait1967}, preliminary={TACS::BarbaneraB1994} } @Article{GoltzGR96, refkey={C1849; PN2542}, title={Comparing Syntactic and Semantic Action Refinement}, author={Ursula Goltz and Roberto Gorrieri and Arend Rensink}, pages={118--143}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2, abstract={The semantic definition of action refinement on labelled configuration structures is compared with the notion of \emph{syntactic substitution}, which can be used as another notion of action refinement in a process algebraic setting. The comparison is done by studying a process algebra equipped with sequential composition, parallel composition with an explicit synchronisation set, and an operator for action refinement. On the one hand, the language (including the refinement operator) is given a configuration structure semantics. On the other hand, a reduction procedure transforms a process term~$P$ into a \emph{flat} term (i.e., with the refinement operator not occuring in it) $\mathit{red}(P)$ by means of syntactic substitution, defined in a structural inductive way. The main aim of the paper is to investigate general conditions under which the terms $P$ and $\mathit{red}(P)$ have the same semantics. The results we present are essentially dependent on the question whether the refined action can be synchronised or not. In the latter case, $P$ and $\mathit{red}(P)$ give rise to isomporphic configuration structures under mild assumptions. The former case is considerably more difficult, since then refinement cannot be expected to distribute over parallel composition. We give necessary and sufficient \emph{semantic} conditions under which distribution still holds up to semantic equivalence. Subsequently, we also give sufficient (but not necessary) \emph{syntactic} conditions for reducible terms. Finally, we generalise these results to a language with recursion.}, references={IC::AcetoH1993, IC::AcetoH1994, IC::BoudolC1994, IC::DeganoG1995, TCS::BoudolCHK1993:31, tcs::DarondeauD1993, tcs::GorrieriMM1990, tcs::Vogler1993}, preliminary={TACS::GoltzGR1994} } @Article{TakahashiAH96, refkey={C1850; PN2543}, title={Normal Proofs and Their Grammar}, author={Masako Takahashi and Yohji Akama and Sachio Hirokawa}, pages={144--153}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2, abstract={We present grammatical (or equational) descriptions of the set of normal inhabitants $\{\, M \mid \Gamma \vdash M:A$, $M$ in $\beta$-normal form$\,\}$ of a given type~$A$ under a given basis~$\Gamma$, both for the standard simple type system (in the partial discharge convention) and for the system in the total discharge convention (or the Prawtiz-style natural deduction system). It is shown that in the latter system we can describe the set by a (finite) context-free grammar, but for the standard system this is not necessarily the case because we may need an infinite supply of fresh (bound) variables to describe the set. In both cases, however, our grammars reflect the structure of normal inhabitants in such a way that, when non-terminals are ignored, a derivation tree of the grammars yielding a $\lambda$-term~$M$ can be identified with B\"ohm tree of~$M$. We give some applications of the grammatical descriptions. Among others, we give simple algorithms for the emptiness/finiteness problem of the set of normal inhabitants of a given type (both for the standard and non-standard systems).}, references={JSYML::Hirokawa1993, tcs::Zaionc1987}, preliminary={TACS::TakahashiAH1994} } @Article{PlaistedS96, refkey={C1769; PN2544}, title={Proof Lengths for Equational Completion}, author={David A. Plaisted and Andrea Sattler-Klein}, pages={154--170}, journal=iandcomp, month={15~} # mar, year=1996, volume=125, number=2, abstract={We first show that ground term-rewriting systems can be completed in a polynomial number of rewriting steps, if the appropriate data structure for terms is used. We then apply this result to study the lengths of critical pair proofs in the non-ground case. We show how these bounds depend on the types of inference steps that are allowed in the proofs.}, references={JACM::Andrews1981, JACM::GallierNPRS1993, IC::GallierNPS1990, JACM::GallierNRS1992, LICS::Lynch1995, JSYMC::MadlenerO1985, JSYMC::MadlenerSO1993, actai::BauerO1984, sicomp::Brand1975} } April 10, 1996 Volume 126, Number 1 @Article{FokkinkG96, refkey={C1709; PN2549}, title={Ntyft/ntyxt Rules Reduce to Ntree Rules}, author={Wan Fokkink and Rob van Glabbeek}, pages={1--10}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={Groote and Vaandrager introduced the \emph{tyft/tyxt format} for Transition System Specifications (TSSs), and established that for each TSS in this format that is \emph{well-founded}, the bisimulation equivalence it induces is a congruence. In this paper, we construct for each TSS in tyft/tyxt format an equivalent TSS that consists of \emph{tree rules} only. As a corollary we can give an affirmative answer to an open question, namely whether the well-foundedness condition in the congruence theorem for tyft/tyxt can be dropped. These results extend to tyft/tyxt with negative premises and predicates.}, references={HTCS::Apt1990, CONCUR::BaetenV1993, JACM::BloomIM1995:232, ICALP::BolG1991, TACS::Fokkink1994, TR::Fokkink1994, JACM::GelderRS1991:620, CLP::GelfondL1988, AMAST::Glabbeek1993, MISC::Glabbeek1995, TCS::Groote1993, IC::GrooteV1992:202, TOPLAS::MartelliM1982, LNCS::Park1981, TR::Plotkin1981, TCS::Simone1985, NJC::Verhoef1995:274} } @Article{HofmannP96, refkey={C1752; PN2554}, title={Positive Subtyping}, author={Martin Hofmann and Benjamin C. Pierce}, pages={11--33}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={The statement $S \le T$ in a $\lambda$-calculus with subtyping is traditionally interpreted by a semantic coercion function of type $\llbracket S \rrbracket \rightarrow \llbracket T\rrbracket$ that extracts the ``$T$ part'' of an element of $S$. If the subtyping relation is restricted to covariant positions, this interpretation may be enriched to include both the implicit coercion and an overwriting function $\mathop{\mathit{put}}[S, T] \in \llbracket S \rrbracket \rightarrow \llbracket T \rrbracket \rightarrow \llbracket S \rrbracket$ that updates the $T$ part of an element of $S$. We give a realizability model and a sound equational theory for a second-order calculus of positive subtyping. Though weaker than familiar calculi of bounded quantification, positive subtyping retains sufficient power to model objects, encapsulation, and message passing, and inheritance. The equational laws relating the behavior of coercions and \emph{put} functions can be used to prove simple properties of the resulting classes in such a way that proofs for superclasses are ``inherited'' by subclasses.}, references={TACS::AbadiC1994, LICS::AbadiP1990, IC::Amadio1991:55, IC::BruceL1990, POPL::Bruce1993, JFP::Bruce1994, JFP::CardelliL1991, MSCS::CardelliM1991, ACMCS::CardelliW1985, IC::CardelliMMS1994:4, IC::Cardelli1988:138, MISC::Cardelli1990, TR::Cardelli1992, MSCS::CompagnoniP1995, TR::Compagnoni1994, THESIS::Cook1989, MSCS::CurienG1992, INDAGM::Bruijn1972, TACS::FisherM1994, BOOK::Gordon1994, BOOK::Gunter1992, JFP::HofmannP1995:593, MISC::KaminR1994, TR::LeavensW1992, MISC::Naraschewski1994, MISC::Oles1985, TCS::PierceS1997:235, JFP::PierceT1994, IC::Pierce1994:131, LNCS::Reynolds1985, TYPES::RobinsonT1988} } @Article{BorealeN96, refkey={C1654; PN2550}, title={A Symbolic Semantics for the {$\pi$}-Calculus}, author={Michele Boreale and Rocco De Nicola}, pages={34--52}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={We use symbolic transition systems as a basis for providing the $\pi$-calculus with an alternative semantics. The latter is more amenable to automatic manipulation and sheds light on the logical differences among different forms of bisimulation over algebras of name-passing processes. Symbolic transitions have the form $P \stackrel{\phi, a}{\longmapsto} P'$, where $\phi$ is a boolean combination of equalities on names that has to hold for the transition to take place, and $a$ is a standard $\pi$-calculus action. On top of the symbolic transition systems, a symbolic bisimulation is defined that captures the standard ones. Finally, a sound and complete proof system is introduced for symbolic bisimulation.}, references={IC::BorealeN1995:279, CONCUR::BorealeN1992, CONCUR::BorealeN1994, CONCUR::Dam1993, MFCS::FerrariMQ1994, TR::Hennessy1991, TCS::HennessyL1995, CONCUR::HennessyL1993, IC::JonssonP1993:272, TR::Lin1994, TAPSOFT::Lin1995, BOOK::Milner1989, IC::MilnerPW1992:1, IC::MilnerPW1992:41, IC::ParrowS1995:174, ACTAI::Sangiorgi1996} } @Article{SayeedA96, refkey={C1665; PN2552}, title={Efficient Perfectly Secure Message Transmission in Synchronous Networks}, author={Hasan Md. Sayeed and Hosame Abu-Amara}, pages={53--61}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={We study perfectly secure message transmission (SMT) in general synchronous networks where processors and communication lines may be Byzantine faulty. Doleve \emph{et al.} (\emph{J. Assoc. Comput. Mach.} \textbf{40}, No.~1, 17--47, Jan.\ 1993) first posed and solved the problem; our work significantly improves on their algorithms in the number of communication bits and the amount of local computation. Hence, our algorithms are better suited for traditional and fiber-optic networks than previous algorithms while requiring the same amount of connectivity. The algorithms we develop do not rely on any complexity theoretic assumptions and simultaneously achieve the three goals of perfect secrecy, perfect resiliency, and worst case time that is linear in the diameter of the network. Our algorithms assume that the containment assumption holds, i.e., there is effectively one adversary who controls and coordinates the activities of the faulty processors and lines. In SMT, a processor (Sender) wishes to transmit a secret message to another processor (Receiver) in such a way as to satisfy secrecy and resiliency requirements simultaneously. In \emph{$1$-way} SMT, Sender can send information to Receiver via the wires that connect them, but Reciever cannot send information to Sender. In \emph{$2$-way} SMT, Sender and Receiver can send information to each other via the wires. A \emph{phase} is a send from Sender to Receiver or vice versa. First, we develope a 3-phase algorithm for 2-way SMT\@. Next, we present a 2-phase algorithm for 2-way SMT\@. To our knowledge, this is the first 2-phse algorithm for SMT that uses communication and computations costs that are polynomial in the number of wires that connect the sender and the receiver. The second algorithm uses less time and more communication bits than the first algorithm. Both the 2-phase and 3-phase algorithms employ new techniques to detect faulty paths. We also present a simple algorithm for 1-way SMT\@.}, references={IEEETN::Abu-Amara1993, STOC::Ben-OrGW1988, STOC::ChaumCD1988, FOCS::ChorGMA1985, JACM::DolevDWY1993, STOC::FeldmanM1988, MISC::GalilHY1989, CACM::McElieceS1981, STOC::RabinB1989} } @Article{AlurT96, refkey={C1689}, title={Contention-Free Complexity of Shared Memory Algorithms}, author={Rajeev Alur and Gadi Taubenfeld}, pages={62--73}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={Worst-case time complexity is a measure of the maximum time needed to solve a problem over all runs. Contention-free time complexity indicates the maximum time needed when a process executes by itself, without competition from other processes. Since contention is rare in well-designed systems, it is important to design algorithms which perform well in the absence of contention. We study the contention-free time complexity of shared memory algorithms using two measures: step complexity, which counts the number of accesses to shared registers; and register complexity, which measures the number of different registers accessed. Depending on the system architecture, one of the two measures more accurately reflects the elapsed time. We provide lower and upper bounds for the contention-free step and register complexity of solving the mutual exclusion problem as a function of the number of processes and the size of the largest register that can be accessed in one atomic step. We also present bounds on the worst-case and contention-free step and register complexities of solving the naming problem. These bounds illustrate that the proposed complexity measures are useful in differentiating among the computational powers of different primitives.}, references={FOCS::AfekS1993, STOC::AspnesHS1991, BurnsL1993, STOC::DworkHW1993, CACM::Dijkstra1965, STOC::FischerMRT1990, IPL::FischerMT1993, TOPLAS::Herlihy1991, IPL::LiptonP1990, STOC::PetersonF1977, STOC::YangA1994} } @Article{Plotkin96, refkey={C1762}, title={On a Question of {H.} {Friedman}}, author={Gordon Plotkin}, pages={74--77}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={In this paper we answer a question of Friedman, providing an $\omega$-separable model~$\mathcal{M}$ of the $\lambda\beta\eta$-calculus. There therefore exists an $a$-separable model for an $a \ge 0$. The model~$\mathcal{M}$ permits no non-trivial enrichment as a partial order; neither does it permit an enrichment as a category with an initial object. The open term model embeds in~$\mathcal{M}$: by way of contrast we provide a model which cannot embed in any non-trivial model separating all pairs of distinct elements.}, references={ICALP::Abramsky1983, BOOK::Barendregt1984, BOOK::ChangK1973, FOCS::Lehmann1976, TCS::Smyth1977, apal::MyhillF1989:79} } @Article{Itoh96, refkey={C1761}, title={Simulating Fair Dice with Biased Coins}, author={Toshiya Itoh}, pages={78--82}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={This paper is concerned with simulating a fair die with a bounded number of coin flips and a bounded number of (possibly biased) coins. As the main result, this paper shows that for an $n \ge 2$, a set of $H(n)$ coins is sufficient to simulate a fair $n$-sided die within $d = \lceil \lg n \rceil$ coin flips, where $H(n)$ is the number of 1's of the binary representation of an integer~$n$, and that for any $n = 2^d - 1$ \ ($d \ge 3$), a set of $d = H(n)$ coins is necessary and sufficient to simulate a fair $n$-sided die within $d = \lceil \lg n \rceil$ coin flips.}, references={STOC::BlumK1989, STOC::BlumLR1990, JCSS::BabaiM1988, IEEETIT::DiffieH1976, IEEETIT::El-Gamal1985, IC::FeldmanINNRS1993, SICOMP::GoldwasserMR1989} } @Article{BoudolL96, refkey={C1706}, title={The Discriminating Power of Multiplicities in the {$\lambda$}-calculus}, author={G{\'e}rard Boudol and Cosimo Laneve}, pages={83--102}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, abstract={The $\lambda$-calculus with multiplicities is a refinement of the lazy $\lambda$-calculus where the argument in an application comes with a multiplicity, which is an upper bound to the number of its uses. This introduces potential deadlocks in the evaluation. We study the discriminating power of this calculus over the usual $\lambda$-terms. We prove in particular that the observational equivalence induced by contexts with multiplicities coincides with the equality of L\'evy-Longo trees associated with $\lambda$-terms. This is a consequence of the characterization we give of the corresponding observational precongruence, as an intensional preorder involving $\eta$-expansion, namely, Ong's lazy Plotkin-Scott-Engeler preorder.}, references={JFP::AbadiCCL1991, AbramskyO1993, Boudol1994, TCS::Levy1976, MSCS::Milner1992, Sangiorgi1994} } @Article{Palsberg96, title={Erratum: Efficient Inference of Object Types}, author={Jens Palsberg}, pages={103--104}, journal=iandcomp, month={10~} # apr, year=1996, volume=126, number=1, references={Palsberg1995} } May 1, 1996 Volume 126, Number 2 @Article{Droste96, refkey={C1620}, title={Aperiodic Languages in Concurrency Monoids}, author={Manfred Droste}, pages={105--113}, journal=iandcomp, month={1~} # may, year=1996, volume=126, number=2, abstract={Automata with concurrency relations~$\mathcal{A}$ are labelled transition systems with a collection of binary relations indicating when two events, in a given state of the automaton, are concurrent. We investigate concurrency monoids~$M(\mathcal{A})$ comprising all finite computation sequences of~$\mathcal{A}$, modulo a canonical congruence induced by the concurrency relations, with composition as monoid operation. Under suitable assumptions on~$\mathcal{A}$ we obtain a characterization of the star-free languages of~$M(\mathcal{A})$. This generalizes a classical result of M.~P. Sch\"utzenberger and a result of G.~Guaiana, A.~Restivo and S.~Salemi in trace theory.}, references={JACM::BerryL1979, TCS::BrachoD1994, TCS::BrachoDK1997:67, TCS::Droste1995, TCS::GuaianaRS1992, Schutzenberger1965:190, TCS::Stark1989} } @Article{HancockJLT96, refkey={C1743}, title={Lower Bounds on Learning Decision Lists and Trees}, author={Thomas Hancock and Tao Jiang and Ming Li and John Tromp}, pages={114--122}, journal=iandcomp, month={1~} # may, year=1996, volume=126, number=2, abstract={$k$-Decision lists and decision trees play important roles in learning theory as well as in practical learning systems. $k$-Decision lists generalize classes such as monomials, $k$-DNF, and $k$-CNF, and like these subclasses they are polynomially PAC-learnable [R.~Rivest, \emph{Mach.\ Learning} \textbf{2} (1987), 229--246]. This leaves open the question of whether $k$-decision lists can be learned as efficiently as $k$-DNF\@. We answer this question negatively in a certain sense, thus disproving a claim in a popular textbook [M.~Anthony and N.~Briggs, ``Computational Learning Theory,'' Cambridge Univ.\ Press, Cambridge, UK, 1992]. Decision trees, on the other hand, are not even known to be polynomially PAC-learnable, despite their widespread practical application. We will show that decision trees are not likely to be efficiently PAC-learnable. We summarize our specific results. The following problems cannot be approximated in polynomial time within a factor of~$2^{\log^\delta n}$ for any~$\delta < 1$, unless $\mathit{NP} \subset \mathit{DTIME}[2^{\mathop{\mathrm{polylog}} n}]$: a generalized set cover, $k$-decision lists, $k$-decision lists by monotone decision lists, and decision trees. Decision lists cannot be approximated in polynomial time within a factor of~$n^\delta$, for some constant~$\delta > 0$, unless $\mathit{NP} = \mathit{P}$. Also, $k$-decision lists with $I$ 0--1 alternations cannot be approximated within a factor~$\log^I n$ unless $\mathit{NP} \subset \mathit{DTIME}[n^{O(\log \log n)}]$ (providing an interesting comparison to the upper bound obtained by A.~Dhagat and L.~Hellerstein [\emph{in} ``FOCS '94,'' pp.~64--74]).}, references={FOCS::DhagatH1994, STOC::BoardP1990, FOCS::AroraLMSS1992, STOC::BellareGLR1993, JACM::BlumerEHW1989, STOC::KearnsLPV1987, STOC::LundY1993, QuinlanR1989, STOC::PapadimitriouY1988:229, JACM::PittV1988, CACM::Valiant1984, JCSS::PapadimitriouY1991} } @Article{BlooKN96, refkey={C1816}, title={The {Barendregt} Cube with Definitions and Generalised Reduction}, author={Roel Bloo and Fairouz Kamareddine and Rob Nederpelt}, pages={123--143}, journal=iandcomp, month={1~} # may, year=1996, volume=126, number=2, abstract={In this paper, we propose to extend the Barendregt Cube by generalizing $\beta$-reduction and by adding definition mechanisms. Generalised reduction allows contracing more visible redexes than usual, and definitions are an important tool to allow for a more flexible typing system. We show that this extension satisfies most of the original properties of the Cube including Church-Rosser, Subject Reduction and Strong Normalisation.}, references={POPL::AriolaFMOW1995, BarendregtKKS1987, TACS::Gardner1994, TCS::KamareddineN1994, JFP::KamareddineN1995, TCS::KamareddineN1996, JFP::KamareddineN1996, JACM::KfouryTU1994, LICS::KfouryW1995, POPL::Launchbury1993, TCS::Regnier1994} } @Article{Ringeissen96, refkey={C1712}, title={Combining Decision Algorithms for Matching in the Union of Disjoint Equational Theories}, author={Christophe Ringeissen}, pages={144--160}, journal=iandcomp, month={1~} # may, year=1996, volume=126, number=2, abstract={This paper addresses the problem of systematically building a matching algorithm for the union of two disjoint theories $E_1 \cup E_2$ provided that matching algorithms are known in both theories $E_1$ and~$E_2$. In general, the blind use of combination techniques introduces unification. Two different restrictions are considered in order to reduce this unification to matching. First, we show that combining matching algorithms (with linear constant restriction) is always sufficient for solving a pure fragment of combined matching problems. Second, the investigated method is complete for the largest class of theories where unification is not needed, including regular collapse-free theories and linear theories. Syntactic conditions are given to define this class of theories in which solving the combined matching problem is performed in a modular way.}, references={JSYMC::Boudet1993, JSYMC::Burckert1989, JSYMC::KirchnerR1994, JSYMC::Nipkow1991, JSYMC::Schmidt-Schauss1989:51, JSYMC::Yelick1987}, preliminary={STACS::Ringeissen1994:187} } @Article{Chaudhuri96, refkey={C1529}, title={Sensitive Functions and Approximate Problems}, author={Shiva Chaudhuri}, pages={161--168}, journal=iandcomp, month={1~} # may, year=1996, volume=126, number=2, abstract={Properties of functions that are good measures of the CRCW PRAM complexity of computing them are investigated. While the \emph{block sensitivity} is known to be a good measure of the CREW PRAM complexity, no such measure is know for CRCW PRAMs. It is shown that the complexity of computing a function is related to its \emph{everywhere sensitivity}, introduced by Vishkin and Wigderson. Specifically, the time required to compute a function $f: D^n \mapsto R$ of everywhere sensitivity $\mathit{es}(f)$ with $P$~processors and unbounded memory is $\Theta(\log [\log \mathit{es}(f)/(\log(|D| + 4P/\mathit{es}(f)))])$. This improves the results of Azar and of Vishkin and Wigderson. This lower bound is used to derive new lower bounds for some \emph{approximate problems}. These problems can often be solved faster than their exact counterparts and for many applications, it is sufficient to solve the approximation problem. It is shown that \emph{approximate selection}, \emph{approximate counting}, \emph{approximate compaction}, and \emph{padded sorting} all require time $\Theta(\log \log n)$ with a linear number of processors, if the level of accuracy desired is moderately high. For these levels of accuracy, no lower bounds are known for these problems on the PRAM model. The lower bounds for some of the problems are tight.}, references={SICOMP::Azar1992, IC::Beame1988, JACM::BeameH1989, FOCS::Chaudhuri1993, SICOMP::CookDR1986, SODA::Hagerup1993, FOCS::HagerupR1992, JACM::LiY1989, SODA::MacKenzie1992, STOC::MatiasV1991, SICOMP::Nisan1991, SICOMP::VishkinW1985, ALGOR::FichRW1988} } May 25, 1996 Volume 127, Number 1 @Article{Vyugin96, refkey={C1617}, title={Bayesianism: An Algorithmic Analysis}, author={Vladimir V. V'yugin}, pages={1--10}, journal=iandcomp, month={25~} # may, year=1996, volume=127, number=1, abstract={The Bayesian program in statistics starts from the assumption that an individual can always ascribe a definite probability to any event. It will be demonstrated that this assumption is incompatible with the natural requirement that the individual's subjective probability distribution should be computable. We shall construct a probabilistic algorithm producing with probability extremely close to~1 an infinite binary sequence which is not random with respect to any computable probability distribution (we use Dawid's notion of randomness, \emph{computable calibration}, but the results hold for other widely known notions of randomness as well). Since the Bayesian knows the algorithm, he must believe that this sequence will be noncalibrable. On the other hand, it seems that the Bayesian must believe that the sequence is random with respect to his own probability distribution. We hope that the discussion of this apparent paradox will clarify the foundations of Bayesian statistics. We analyse also the time of computation and the place of ``losing randomness.'' We show that we need only polynomail time and space to demonstrate non-calibration effects on finite sequences.}, references={Levin1984, Martin-Lof1966, Vovk1992} } @Article{Gianantonio96, refkey={C1615}, title={Real Number Computability and Domain Theory}, author={Pietro Di Gianantonio}, pages={11--25}, journal=iandcomp, month={25~} # may, year=1996, volume=127, number=1, abstract={We present the different constructive definitions of real number that can be found in the literature. Using domain theory we analyse the notion of computability that is substantiated by these definitions and we give a definition of computability for real numbers and for functions acting on them. This definition of computability turns out to be equivalent to other definitions given in the literature using different methods. Domain theory is a useful tool to study higher order computability on real numbers. An interesting connection between Scott topology and the standard topologies on the real line and on the space of continuous functions on reals is stated. An important result in this paper is the proof that every computable functional on real numbers is continuous w.r.t.\ the compact open topology on the function space.}, references={TCS::Sunderhauf1995, TCS::Smyth1977, TCS::Wiedmer1980, TCS::WeihrauchS1981}, preliminary={MFCS::Gianantonio1993} } @Article{AcetoFGI96, refkey={C1826}, title={Axiomatizing Prefix Iteration with Silent Steps}, author={Luca Aceto and Rob van Glabbeek and Wan Fokkink and Anna Ing{\'o}lfsd{\'o}ttir}, pages={26--40}, journal=iandcomp, month={25~} # may, year=1996, volume=127, number=1, abstract={Prefix iteration is a variation on the original binary version of the Kleene star operation $P^*Q$, obtained by restricting the first argument to be an atomic action. The interaction of prefix iteration with silent steps is studied in the setting of Milner's basic CCS\@. Complete equational axiomatizations are given for four notions of behavioural congruence over basic CCS with prefix iteration, viz.~branching congruence, $\eta$-congruence, delay congruence and weak congruence. The completeness proofs for $\eta$-, delay, and weak congruence are obtained by reduction to the completeness theorem for branching congruence. It is also argued that the use of the completeness result for branching congruence in obtaining the completeness result for weak congruence leads to a considerable simplification with respect to the only direct proof presented in the literature. The preliminaries and the completeness proofs focus on open terms, i.e., terms that may contain process variables. As a byproduct, the $\omega$-completeness of the axiomatizations is obtained as well as their completeness for closed terms.}, references={IC::AcetoBV1994, TCS::BaetenBK1987, IPL::Basten1996, TCS::Bloom1995, JACM::CopiEW1958, IPL::Fokkink1994, JACM::GlabbeekW1996, IC::Hennessy1981, JACM::HennessyM1985, CACM::Keller1976, IC::Milner1989, LICS::Sewell1994} } @Article{Vogler96, refkey={C1751}, title={The Limit of {$\mathrm{Split}_n$}-Language Equivalence}, author={Walter Vogler}, pages={41--61}, journal=iandcomp, month={25~} # may, year=1996, volume=127, number=1, abstract={Splitting is a simple form of action refinement that may be used to express the duration of actions. In particular, $\mathit{split}_n$ subdivides each action into $n$ phases. Petri nets $N$ and $N'$ are $\mathit{split}_n$-language equivalent, if $\mathit{split}_n(N)$ and $\mathit{split}_n(N')$ are language equivalent. It is known that these equivalences get finer and finer with increasing~$n$. This paper characterizes the limit of this sequence by a newly defined partial order semantics. This semantics is obtained from the interval-semiword semantics, which is fully abstract for action refinement and language equivalence, by closing it under a special swap operation. The new swap equivalence lies strictly between interval-semiword and step-sequence equivalence.}, references={IC::AcetoH1993, IC::DeganoG1995, IC::GorrieriL1995, IC::GoltzR1983, SICOMP::Hennessy1988, TCS::Vogler1993, IC::Vogler1995:149} } Volume 127, Number 2 June 15, 1996 Special Conference Issue 1993 IEEE Symposium on Logic in Computer Science Guest Editor: Moshe Y. Vardi This Issue is Dedicated to the Memory of Our Colleague and Friend Paris Christos Kanellakis (December 3, 1953 -- December 20, 1995) @Article{Vardi96:64, refkey={C1864}, title={Editor's Foreword}, author={Moshe Y. Vardi}, pages={64}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2 } @Article{Vardi96:65, refkey={C1863}, title={In Memoriam: {Paris C.\ Kanellakis} (1953--1995)}, author={Moshe Y. Vardi}, pages={65}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2 } @Article{Pitts96, refkey={C1553}, title={Relational Properties of Domains}, author={Andrew M. Pitts}, pages={66--90}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={New tools are presented for reasoning about properties of recursively defined domains. We work within a general, category-theoretic framework for various notions of ``relation'' on domains and for actions of domain constructors on relations. Freyd's analysis of recursive types in terms of a property of mixed initiality/finality is transferred to a corresponding property of \emph{invariant} relations. The existence of invariant relations is proved under completeness assumptions about the notion of relation. We show how this leads to simpler proofs of the computational adequacy of denotational semantics for functional programming languages with user-declared datatypes. We show how the initiality/finality property of invariant relations can be specialized to yield an induction principle for admissible subsets of recursively defined domains, generalizing the principle of structural induction for inductively defined sets. We also show how the initiality/finality property gives rise to the co-induction principle studied by the author [\emph{Theoret.\ Comput.\ Sci.}\ \textbf{124}, 195--219 (1994)], by which equalities between the elements of recursively defined domains may be proved via an appropriate notion of ``bisimulation.''}, references={Abramsky1991, AbramskyO1993, CroleP1992, LICS::Fiore1993, LICS::Meyer1988, POPL::OHearnT1993, LICS::Pitts1993:86, FACS::Thompson1989}, preliminary={LICS::Pitts1993} } @Article{AbdullaJ96:91, refkey={C1554}, title={Verifying Programs with Unreliable Channels}, author={Parosh Aziz Abdulla and Bengt Jonsson}, pages={91--101}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={We consider the verification of a particular class of infinite-state systems, namely systems consisting of finite-state processes that communicate via unbounded lossy FIFO channels. This class is able to model, e.g., link protocols such as the Alternating Bit Protocol and HDLC\@. For this class of systems, we show that several interesting verification problems are decidable by giving algorithms for verifying (1)~the \emph{reachability problem}---is a finite set of global states reachable from some other global state of the system? (2)~\emph{safety properties over traces} formulated as regular sets of allowed finite traces, and (3)~\emph{eventuality properties}---do all computations of a system eventually reach a given set of states? We have used the algorithms to verify some idealized sliding-window protocols with reasonable time and space resources. Our results should be contrasted with the well-known fact that these problems are undecidable for systems with unbounded \emph{perfect} FIFO channels.}, references={lics::alurcd1990:414, lics::burchcmdh1990:428, cacm::bartlettsw1969, jacm::brandz1983:323, toplas::clarkees1986:244, jacm::germans1992:675, tcs::jancar1990:71, ic::jonssonp1993:272, jcss::karpm1969:147, toplas::pengp1991:399, tcs::rosiery1986, lics::vardiw1986:332, popl::wolper1986:184}, preliminary={LICS::AbdullaJ1993} } @Article{MitchellV96, refkey={C1555}, title={Standard {ML--NJ} Weak Polymorphism and Imperative Constructs}, author={John Mitchell and Ramesh Viswanathan}, pages={102--116}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={Standard ML of New Jersey (SML--NL) uses ``weak type variables'' to restrict the polymorphic use of functions that may allocate reference cells, manipulate continuations, or use exceptions. However, the type system used in the SML--NJ compiler has not previously been presented in a form other than source code nor proved correct. We present a set of typing rules, based on analysis of the concepts underlying ``weak polymorphism'', that appears to subsume the implementation algorithm and uses type variables of only a slightly more general nature than the compiler. One insight in the analysis is that allowing a variable to occur both ``ordinarily'' and ``weakly'' in a type permits a simpler and more flexible formulation of the typing rules. In particular, we are able to treat applications of polymorphic functions to imperative arguments with greater flexibility than SML--NJ\@. The soundness of the type system is proved for imperative code using operational semantics, by showing that evaluation preserves typability. By incorporating assumptions about memory addresses in the type system, we avoid proofs by co-induction.}, references={JFP::GreinerJ1996:111, POPL::JouvelotG1991, JACM::KfouryTU1994:368, POPL::LeroyW1991, LICS::TalpinJ1992, Tofte1990}, preliminary={LICS::HoangMV1993:15} } @Article{HillebrandKM96, refkey={C1556}, title={Database Query Languages Embedded in the Typed Lambda Calculus}, author={Gerd G. Hillebrand and Paris C. Kanellakis and Harry G. Mairson}, pages={117--144}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={We investigate the expressive power of the typed $\lambda$-calculus when expressing computations over finite structures, i.e., databases. We show that the simply typed $\lambda$-calculus can express various database query languages such as the relational algebra, fixpoint logic, and the complex object algebra. In our embeddings, inputs and outputs are $\lambda$-terms encoding databases, and a program expressing a query is a $\lambda$-term which types when applied to an input and reduces to an output. Our embeddings have the additional property that PTIME computable queries are expressible by programs that, when applied to an input, reduce to an output in a PTIME sequence of reduction steps. Under our database input-output conventions, all elementary queries are expressible in the order-5 (order-4) fragment of the types $\lambda$-calculus (with equality).}, references={STOC::BellantoniC1992, TCS::BunemanNTW1995, acmtds::BunemanFN1982, JLOGP::ChandraH1985, JACM::FortuneLO1983, FOCS::Gurevich1983, LICS::HillebrandKM1993, IC::Immerman1986, LICS::KfouryTU1987, IC::Leivant1990, CACM::McCarthy1960, JSYML::Statman1982, STOC::Vardi1982}, preliminary={LICS::HillebrandKM1993} } @Article{Brookes96, refkey={C1557}, title={Full Abstraction for a Shared-Variable Parallel Language}, author={Stephen Brookes}, pages={145--163}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={We give a new denotational semantics for a shared-variable parallel programming language and prove full abstraction: the semantics gives identical meanings to all commands if and only if they induce the same behavior in all program contexts. The meaning of a command is a set of ``transition traces,'' which record the ways in which a command may interact with and be affected by its environment. We show how to modify the semantics to incorporate new program constructs, to allow for different levels of granularity or atomicity, and to model fair infinite computation, in each case achieving full abstraction with respect to an appropriate notion of program behavior.}, references={TCS::AbadiP1993, JACM::AptP1986, LICS::Brookes1993, POPL::Jonsson1989, TCS::Milner1977, TCS::Plotkin1977, FOCS::Russell1989}, preliminary={LICS::Brookes1993} } @Article{JoyalNW96, refkey={C1558}, title={Bisimulation from Open Maps}, author={Andr{\'e} Joyal and Mogens Nielsen and Glynn Winskel}, pages={164--185}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={An abstract definition of bisimulation is presented. It makes possible a uniform definition of bisimulation across a range of different models for parallel computation presented as categories. As examples, transition systems, synchronisation trees, transition systems with independence (an abstraction from Petri nets), and labelled event structures are considered. On transition systems the abstract definition readily specialises to Milner's strong bisimulation. On event structures it explains and leads to a strengthening of the history-preserving bisimulation of Rabinovich and Trakhtenbrot and van~Glabeek and Goltz. A tie-up with open maps in a (pre)topos, as they appear in the work of Joyal and Moerdijk, brings to light a new model, presheaves on categories of pomsets, into which the usual category of labelled event structures embeds fully and faithfully. As an indication of its promise, this new presheaf model has ``refinement'' operators. The general approach yields a logic, generalising Hennessy--Milner logic, which is characteristic for the generalised notion of bisimulation.}, references={IC::BensonB1988, APAL::JoyalM1994}, preliminary={LICS::JoyalNW1993} } @Article{Fiore96, refkey={C1560}, title={A Coinduction Principle for Recursive Data Types Based on Bisimulation}, author={Marcelo P. Fiore}, pages={186--198}, journal=iandcomp, month={15~} # jun, year=1996, volume=127, number=2, abstract={The concept of bisimulation from concurrency theory is used to reason about recursively defined data types. From two strong-extensionality theorems stating that the equality (resp.\ inequality) relation is maximal among all bisimulations, a proof principle for the final coalgebra of an endofunctor on a category of data types (resp.\ domains) is obtained. As an application of the theory developed, an internal full abstraction result (in the sense of S.~Abramsky and C.-H. L.~Ong [\emph{Inform.\ and Comput.}\ \textbf{105}, 159--267 (1993)] for the canonical model of the untyped call-by-value $\lambda$-calculus is proved. Also, the operational notion of bisimulation and the denotational notion of final semantics are related by means of conditions under which both coincide.}, references={IC::Abramsky1991, TOPLAS::AmadioC1993, IC::ArbibM1982, IC::AbramskyO1993, TCS::Courcelle1983, LICS::Freyd1990, LICS::Pitts1993:86, TCS::Pitts1994, IC::RobinsonR1988}, preliminary={LICS::Fiore1993} } Volume 128, Number 1 July 10, 1996 @Article{LynchV96, refkey={C1476; PN2546}, title={Forward and Backward Simulations, {II}: Timing-Based Systems}, author={Nancy Lynch and Frits Vaandrager}, pages={1--25}, journal=iandcomp, month={10~} # jul, year=1996, volume=128, number=1, abstract={A general automaton model for timing-based systems is presented and is used as the context for developing a variety of simulation proof techniques for such systems. These techniques include (1)~refinements, (2)~forward and backward simulations, (3)~hybrid forward-backward and backward-forward simulations, and (4)~history and prophecy relations. Relationships between the different types of simulations, as well as soundness and completeness results, are stated and proved. These results are (with one exception) analogous to the results for untimed systems in Part~I of this paper. In fact, many of the results for the timed case are obtained as consequences of the analogous results for the untimed case.}, references={TCS::AbadiL1991, TOPLAS::AbadiL1994, THESIS::Aggarwal1994, THESIS::Alur1991, TCS::AlurCHHHNOSY1995:3, LNCS::AlurCHH1993, TCS::AlurD1994, RTSS::AlurHH1993, FACS::BaetenB1991:142, CONCUR::BerryC1984, LNCS::BosscherPV1994, TCS::DaviesS1995:243, ICALP::GawlickSSL1994, RTSOS::GerberL1989, THESIS::Glabbeek1990, TR::Griffioen1995, MISC::Groote1990, BOOK::GuttagH1993, RTSS::HeitmeyerL1994, IPL::Henzinger1992, REX::HenzingerP1992, IC::HenzingerNSY1994, CAV::Jeffrey1992, TR::JeffreyV1993, IC::KlarlundS1993, CONCUR::Klusener1992, TOPLAS::Lamport1994, FORTE::LampsonS1993, THESIS::Luchangco1994, ICFDTDSCP::LuchangcoSGL1994, REX::Lynch1994, BOOK::Lynch1995, DC::LynchA1992, PODC::LynchSS1994:314, PODC::LynchT1987, CONCUR::VaandragerL1992:436, REX::LynchV1992, TR::LynchV1993, IC::LynchV1995:214, EWRTHS::LynchW1995, BOOK::MannaP1992, LNCS::MannaP1993, CONCUR::MerrittMT1991, BOOK::Milner1989, CONCUR::MollerT1990, LNCS::NicollinOSY1993, MISC::NicollinRSV1990, ACTAI::NicollinSY1993, FTRTFTS::Pnueli1994, TCS::ReedR1988, THESIS::Segala1995, IPL::Sistla1991, THESIS::Sogaard-Andersen1993, TR::Sogaard-AndersenLL1993, THESIS::Soylemez1994, CONCUR::Yi1990, THESIS::Zwarico1988} } @Article{MasonST96, refkey={C1402}, title={From Operational Semantics to Domain Theory}, author={Ian A. Mason and Scott F. Smith and Carolyn L. Talcott}, pages={26--47}, journal=iandcomp, month={10~} # jul, year=1996, volume=128, number=1, abstract={This paper builds domain theoretic concepts upon an operational foundation. The basic operational theory consists of a single step reduction system from which an operational ordering and equivalence on programs are defined. The theory is then extended to include concepts from domain theory, including the notions of directed set, least upper bound, complete partial order, monotonicity, continuity, finite element, $\omega$-algebraicity, full abstraction, and least fixed point properties. We conclude by using these concepts to construct a (strongly) fully abstract continuous model for our language. In addition we generalize a result of Milner and prove the uniqueness of such models.}, references={TOPLAS::AbadiCPP1991, IC::Bloom1990, TCS::FelleisenFKD1987:205, IC::HonsellMST1995, LICS::Howe1989, POPL::MacQueenPS1984, JFP::MasonT1991, IC::Meyer1982, TCS::Milner1977, FOCS::Ong1988, TCS::Pitts1994, SICOMP::Wadsworth1976} } @Article{KilianS96, refkey={C1687}, title={The Dynamic Universality of Sigmoidal Neural Networks}, author={Joe Kilian and Hava T. Siegelmann}, pages={48--56}, journal=iandcomp, month={10~} # jul, year=1996, volume=128, number=1, abstract={We investigate the computational power of recurrent neural networks that apply the sigmoid activation function $\sigma(x) = [2/(1 + e^{-x})] - 1$. These networks are extensively used in automatic learning of non-linear dynamical behavior. We show that in the noiseless model, there exists a universal architecture that can be used to compute any recursive (Turing) function. This is the first result of its kind for the sigmoid activation function; previous techniques only applied to linearized and truncated version of this function. The significance of our result, besides the proving technique itself, lies in the popularity of the sigmoidal function in engineering applications of artificial neural networks and in biological modelling. Our techniques can be applied to a much more general class of ``sigmoidal-like'' activation functions, suggesting that Turing universality is a relatively common property of recurrent neural models.} } @Article{VargheseL96, refkey={C1730}, title={A Tradeoff Between Safety and Liveness for Randomized Coordinated Attack}, author={George Varghese and Nancy A. Lynch}, pages={57--71}, journal=iandcomp, month={10~} # jul, year=1996, volume=128, number=1, abstract={We study \emph{randomized, synchronous} protocols for coordinated attack. Such protocols trade off the number of rounds ($N$), the worst-case probability of disagreement ($U$), and the probability that all generals attach ($\mathcal{L}$). We prove a nearly tight bound on the tradeoff between $\mathcal{L}$ and~$U$ ($\mathcal{L}/U \le N$) for a \emph{strong} adversary that destroys any subset of messages. Our techniques may be useful for other problems that allow a non-zero probability of disagreement.}, references={JALGO::Dolev1982, STOC::GrahamY1989, CACM::Lamport1977, TOPLAS::LamportSP1982, POPL::LehmannR1981} } Volume 128, Number 2 July 10, 1996 @Article{CaseJS96, refkey={C1802}, title={Machine Induction Without Revolutionary Changes in Hypothesis Size}, author={John Case and Sanjay Jain and Arun Sharma}, pages={73--86}, journal=iandcomp, month={1~} # aug, year=1996, volume=128, number=2, abstract={This paper provides a beginning study of the effects on inductive inference of paradigm shifts whose absence is approximately modeled by various formal approaches to forbidding large changes in the size of programs conjectured. One approach, called \emph{severely parsimonious}, requires all the programs conjectured on the way to be nearly (i.e., within a recursive function of) minimal size. It is shown that this very conservative constraint allows learning infinite classes of functions, but \emph{not} infinite r.e.\ classes of functions. Another approach, called \emph{non-revolutionary}, requires all conjectures to be nearly the same size as one another. This quite conservative constraint is, nonetheless, shown to permit learning some infinite r.e.\ classes of functions. Allowing up to one extra \emph{bounded size} mind change towards a final program learned certainly does not appear revolutionary. However, somewhat surprisingly for scientific (inductive) inference, it is shown that there are classes learnable \emph{with} the non-revolutionary constraint (respectively, with severe parsimony), up to $(i + 1)$ mind changes, and no anomalies, which classes can\emph{not} be learned with no size constraint, an unbounded, finite number of anomalies in the final program, but with no more than $i$ mind changes. Hence, in some cases, the possibility of one extra mind change is considerably more liberating than removal of very conservative size shift constraints. The proofs of these results are also combinatorially interesting.}, references={TCS::AngluinGS1989, JSYML::BaligaCJS1994, SOVMD::BarzdinF1972, LVUZR::BarzdinF1974, MFCS::BarzdinP1973, IC::BlumB1975, JACM::Blum1967:322, IC::Blum1967, COLT::Case1988, TR::Case1992, KYBER::CaseJM1994, IJFCS::CaseJS1992, JCSS::CaseJS1994, LNCS::CaseJS1995, TCS::CaseS1983, IC::Chen1982, LNCS::Freivalds1975, COLT::Freivalds1990, TAP::FreivaldsK1977, FOCS::Fulk1990, IC::FulkJ1994, IC::Gold1967, IPL::Jain1995, TCS::JainS1994, MST::JainS1995, BOOK::Kuhn1970, LNAI::LangeW1994, BOOK::MachteyY1978, IC::Meyer1972, ACM::MeyerR1967, BOOK::Moody1935, BOOK::OshersonSW1986, BOOK::Putnam1975, THESIS::Riccardi1980, JCSS::Riccardi1981, JSYML::Rogers1958, BOOK::Rogers1967, LNCS::Royer1987, BOOK::RoyerC1994, JSYML::Shapiro1971, MIND::Thorburn1915, MIND::Thorburn1918, EIK::Wiehagen1986, LNAI::Wiehagen1990} } @Article{RomanikV96, refkey={C1636}, title={Using {Vapnik-Chervonenkis} Dimension to Analyze the Testing Complexity of Program Segments}, author={Kathleen Romanik and Jeffrey Scott Vitter}, pages={87--108}, journal=iandcomp, month={1~} # aug, year=1996, volume=128, number=2, abstract={We examine the complexity of testing different program constructs. We do this by defining a measure of testing complexity known as VCP-dimension, which is similar to the Vapnik-Chervonenkis dimension, and applying it to classes of programs, where all programs in a class share the same syntactic structure. VCP-dimension gives bounds on the number of test points needed to determine that a program is approximately correct, so by studying it for a class of programs we gain insight into the difficulty of testing the program construct represented by the class. We investigate the VCP-dimension of straight line code, if--then--else statements, and for loops. We also compare the VCP-dimension of nested and sequential if--then--else statements as well as that of two types of for loops with embedded if--then--else statements. Finally, we perform an empirical study to estimate the expected complexity of straight line code.}, references={sicomp::BorodinC1976, jacm::BlumerEHW1989, stoc::BlumK1989, stoc::BlumLR1990, stoc::GemmellLRSW1991, Haussler1992, stoc::MacintyreS1993} } @Article{HarelS96, refkey={C1647}, title={More on Nonregular {PDL}: Finite Models and {Fibonacci}-Like Programs}, author={David Harel and Eli Singerman}, pages={109--118}, journal=iandcomp, month={1~} # aug, year=1996, volume=128, number=2, abstract={We continue research on enriching propositional dynamic logic (PDL) with nonregular programs. Previous work indicates that the general problem of characterizing those extensions for which PDL becomes undecidable is probably very hard. After observing that any nonregular extension increases the expressive power of PDL, we concentrate on one-letter extensions. First, we address the issue of finite models: A general condition is formulated, and is proven to be sufficient for a one-letter extension to violate the finite model property. We show the condition to hold in several cases, including all polynomials, sums of primes, and linear recurrences. We then build on a technique of Paterson and Harel, and show that the validity problem for PDL enriched with any Fibonacci-like sequence is $\Pi^1_1$-complete.}, references={jcss::FischerL1979, jcss::HarelP1984, jcss::HarelPS1983, sicomp::HarelR1993, jacm::Parikh1966, focs::Pratt1976, jcss::Pratt1980} } @Article{HanT96, refkey={C1785}, title={Restricted Information from Nonadaptive Queries to {NP}}, author={Yenjo Han and Thomas Thierauf}, pages={119--125}, journal=iandcomp, month={1~} # aug, year=1996, volume=128, number=2, abstract={We investigate classes of sets that can be decided by bounded truth-table reductions to an NP set in which evaluators do \emph{not} have full access to the queries but get only restricted information such as the number of queries that are in the oracle set or even just this number modulo~$m$, for some $m \ge 2$. We also investigate the case in which evaluators are nondeterministic. We show that when we vary the information that evaluators get, this can change the resulting power of the evaluators. We locate all these classes within levels of the Boolean hierarchy which allows us to compare the complexity of such classes.}, references={TR::AgrawalBT1996, SCTC::AmirBG1990, BOOK::BalcazarDG1988, TCS::Beigel1991, SCTC::BussH1988, SICOMP::CaiGHHSWW1988:1232, BOOK::HopcroftU1979, THESIS::Kadin1988, sicomp::Kadin1988:1263, LEM::KarpL1982, RAIRO::KoblerSW1987, sicomp::KoblerT1994, TCS::LadnerLS1975, sicomp::Wagner1990, CFCT::Wechsung1985} } @Article{Changizi96, refkey={C1836}, title={Self-Monitoring Machines and an {$\omega^\omega$} Hierarchy of Loops}, author={Mark Changizi}, pages={127--138}, journal=iandcomp, month={1~} # aug, year=1996, volume=128, number=2, abstract={An ordinal hierarchy of recursive functions is developed based on the level to which a function requires a machine computing it to monitor and make decisions concerning itself. The major theorem states that the functions with self-monitoring level below $\omega^\omega$ are precisely the class of loop functions (or primitive recursive functions.}, references={IC::FreivaldsS1993} } Volume 129, Number 1 August 25, 1996 @Article{Hella96, refkey={C1655; PN2590}, title={Logical hierarchies in {PTIME}}, author={Lauri Hella}, pages={1--19}, journal=iandcomp, month={25~} # aug, year=1996, volume=129, number=1, abstract={We consider the problem of finding a characterization for polynomial time computable queries on finite structures in terms of logical definability. It is well known that fixpoint logic provides such a characterization in the presence of a built-in linear order, but without linear order even very simple polynomial time queries involving counting are not expressible in fixpoint logic. Our approach to the problem is based on generalized quantifiers. A generalized quantifier is $n$-ary if it binds any number of formulas, but at most $n$ variables in each formula. We prove that, for each natural number~$n$, there is a query on finite structures which is expressible in fixpoint logic, but not in the extension of first-order logic by any set of $n$-ary quantifiers. It follows that the expressive power of fixpoint logic cannot be captured by adding finitely many quantifiers to first-order logic. Furthermore, we prove that, for each natural number~$n$, there is a polynomial time computable query which is not definable in any extension of fixpoint logic by $n$-ary quantifiers. In particular, this rules out the possibility of characterizing PTIME in terms of definability in fixpoint logic extended by a finite set of generalized quantifiers.}, references={stoc::AbiteboulV1991, jcss::ChandraH1982, jlogc::Dawar1995, lics::DawarH1994, DawarH1995, DawarLW1995, lics::Gottlob1995, Immerman1986, sicomp::Immerman1987, Kolaitis1991, apal::KolaitisV1995, ic::KolaitisV1992, lics::KolaitisV1992:46, stoc::Vardi1982}, preliminary={LICS::Hella1992:360} } @Article{JennerMT96, refkey={C1760; PN2588}, title={Logspace and Logtime Leaf Languages}, author={Birgit Jenner and Pierre McKenzie and Denis Th{\'e}rien}, pages={21--33}, journal=iandcomp, month={25~} # aug, year=1996, volume=129, number=1, abstract={The computation tree of a nondeterministic machine~$M$ with input~$x$ gives rise to a \emph{leaf string} formed by concatenating the outcomes of all the computations in the tree in lexicographical order. We may characterize problems by considering, for a particular ``leaf language''~$Y$, the set of all~$x$ for which the leaf string of~$M$ is contained in~$Y$. In this way, in the context of polynomial time computation, leaf languages were shown to capture many complexity classes. In this paper, we study the expressibility of the leaf language mechanism in the contexts of logarithmic space and of logarithmic time computation. We show that logspace leaf languages yield a much finer classification scheme for complexity classes than polynomial time leaf languages, capturing also many classes within~$P$. In contrast, logtime leaf languages basically behave like logtime reducibilities. Both cases are more subtle to handle than the polynomial time case. We also raise the issue of balanced versus nonbalanced computation trees underlying the leaf language. We indicate that it is a nontrivial problem to obtain information about the leaf string of a nonbalanced computation tree and present conditions under which it does not matter whether the computation tree is balanced or not.}, references={TCS::AlvarezJ1993, tcs::Angluin1980, sicomp::BakerGS1975, tcs::BakerS1979, jcss::Barrington1989, jcss::BarringtonIS1990, ic::BarringtonST1990, jacm::BarringtonT1988, sicomp::BeaudryMPT1997:138, tcs::BedardLM1993, tcs::BeigelG1992, jcss::BorodinFKLT1981, tcs::BovetCS1992, mst::BuntrockDHM1992, stoc::Buss1987, sicomp::BussCGR1992, tcs::CaiC1995, sicomp::CaiCH1998, jacm::ChandraKS1981, jcss::CohenB1971, Cook1985, mst::FurstSS1984, stoc::Hastad1986:6, mst::HertrampfVW1996, sicomp::Immerman1988, jcss::Ruzzo1981, jcss::RuzzoST1984, jcss::Savitch1970, tcs::Stockmeyer1976, jacm::Sudborough1978:405, actai::Szelepcsenyi1988, tcs::Valiant1979, focs::Yao1985:1, focs::Yao1990:619} } @Article{Dam96, refkey={C1595; PN2584}, title={Model Checking Mobile Processes}, author={Mads Dam}, pages={35--51}, journal=iandcomp, month={25~} # aug, year=1996, volume=129, number=1, abstract={We introduce a temporal logic for the polyadic $\pi$-calculus based on fixed point extensions of Hennessy--Milner logic. Features are added to account for parametrisation, generation, and passing of names, including the use, following Milner, of dependent sum and product to account for (unlocalised) input and output, and explicit parametrisation on names using $\lambda$-abstraction and application. The latter provides a single name binding mechanism supporting all parametrisation needed. A proof system and decision procedure is developed based on Stirling and Walker's approach to model checking the modal $\mu$-calculus using constants. One difficulty, for both conceptual and efficiency-based reasons, is to avoid the explicit use of the $\omega$-rule for parametrised processes. A key idea, following Hennessy and Lin's approach to deciding bisimulation for certain types of value-passing processes, is the relativisation of correctness assertions to conditions on names. Based on this idea, a proof system and a decision procedure are obtained for arbitrary $\pi$-calculus processes with finite control, $\pi$-calculus correlates of CCS finite-state processes, avoiding the use of parallel composition in recursively defined processes.}, references={toplas::CleavelandPS1993, tcs::Dam1994:77, JonssonP1993:272, mscs::Milner1992, tcs::MilnerPW1993, MilnerPW1992:1, MilnerPW1992:41, facs::OravaP1992, tcs::Park1976, StreettE1989, tcs::Stirling1987, tcs::StirlingW1991} } @Article{ApsitisFS96, refkey={C1815; PN2594}, title={On Duality in Learning and the Selection of Learning Terms}, author={Kalvis Aps{\=\i}tis and R{\=u}si{\c{n}}{\v{s}} Freivalds and Carl H. Smith}, pages={53--62}, journal=iandcomp, month={25~} # aug, year=1996, volume=129, number=1, abstract={Previous work in inductive inference dealt mostly with finding one or several machines (IIMs) that successfully learn collections of functions. Herein we start with a class of functions and consider \emph{the learner set} of all IIMs that are successful at learning the given class. Applying this perspective to the case of team inference leads to the notion of \emph{diversification} for a class of functions. This enables us to distinguish between several flavours of IIMs all of which must be represented in a team learning the given class.}, references={stoc::ApsitisFS1994, tcs::AngluinGS1989, acmcs::AngluinS1983, ic::BlumB1975, tcs::CaseS1983, ic::FreivaldsSV1989, ic::Gold1967, KinberZ1991, jacm::Pitt1989, PittS1988, jacm::Smith1982}, preliminary={STOC::ApsitisFS1994} } @Article{AnoulovaFPS96, refkey={C1441; PN2593}, title={Probably Almost {Bayes} Decisions}, author={Svetlana Anoulova and Paul Fischer and Stefan P{\"o}lt and Hans Ulrich Simon}, pages={63--71}, journal=iandcomp, month={25~} # aug, year=1996, volume=129, number=1, abstract={In this paper, we investigate the problem of classifying objects which are given by feature vectors with Boolean entries. Our aim is to ``(efficiently) learn probably almost optimal classifications'' from examples. A classical approach in pattern recognition uses empirical estimations of the Bayesian discriminant functions for this purpose. We analyze this approach for different classes of distribution functions of Boolean features: $k$th order Bahadur--Lazarsfeld expansions and $k$th order Chow expansions. In both cases, we obtain upper bounds for the required sample size which are small polynomials in the relevant parameters and which match the lower bounds known for these classes. Moreover, the learning algorithms are efficient.}, references={jacm::BlumerEHW1989, ic::Haussler1992, focs::KearnsS1990} } Volume 129, Number 2 September 15, 1996 @Article{Zhang96, refkey={C1569; PN2589}, title={A New Research into Default Logic}, author={Zhang Mingyi}, pages={73--85}, journal=iandcomp, month={15~} # sep, year=1996, volume=129, number=2, abstract={In previous papers some important properties of extensions of general default theories were given. In order to dedicate further research to default logic, a characterization of extensions is presented again and some new algorithms for reasoning tasks in default logic are presented in this paper. A class of default theories, auto-compatible default theory, is also developed. We show that the characterization and notions of compatibility and auto-compatibility, suitably applied to logic programs, yield some sufficient conditions of existence of answer sets. All these essentially develop the theories of Reiter and his followers.}, references={jlogc::Gottlob1992, jlogp::Kunen1989, BidoitF1991} } @Article{AtenieseBSS96, refkey={C1898; PN2592}, title={Visual Cryptography for General Access Structures}, author={Giuseppe Ateniese and Carlo Blundo and Alfredo De Santis and Douglas R. Stinson}, pages={86--106}, journal=iandcomp, month={15~} # sep, year=1996, volume=129, number=2, abstract={A visual cryptography scheme for a set~$\mathcal{P}$ of $n$ participants is a method of encoding a secret image $SI$ into $n$ shadow images called shares, where each participant in~$\mathcal{P}$ receives one share. Certain qualified subsets of participants can ``visually'' recover the secret image, but other, forbidden, sets of participants have no information (in an information-theoretic sense) on~$SI$. A ``visual'' recovery for a set $X \subseteq \mathcal{P}$ consists of xeroxing the shares given to the participants in~$X$ onto transparencies, and then stacking them. The participants in a qualified set~$X$ will be able to see the secret image without any knowledge of cryptography and without performing any cryptographic computation. In this paper we propose two techniques for constructing visual cryptography schemes for general access structures. We analyze the structure of visual cryptography schemes and we prove bounds on the size of the shares distributed to the participants in the scheme. We provide a novel technique for realizing $k$ out of~$n$ threshold visual cryptography schemes. Our construction for $k$ out of~$n$ visual cryptography schemes is better with respect to pixel expansion than the one proposed by M.~Naor and A.~Shamir (Visual cryptography, \emph{in} ``Advances in Cryptology---Eurocrypt~'94'' CA.\ De~Santis, Ed., Lecture Notes in Computer Science, Vol.~950, pp.~1--12, Springer-Verlag, Berlin, 1995) and for the case of 2 out of~$n$ is the best possible. Finally, we consider graph-based access structures, i.e., access structures in which any qualified set of participants contains at least an edge of a given graph whose vertices represent the participants of the scheme.}, references={jcrypt::BlundoSSV1995, jcrypt::BrickellS1992, focs::Mehlhorn1982} } @Article{AcetoI96, refkey={C1742; PN2595}, title={{CPO} Models for Compact {GSOS} Languages}, author={Luca Aceto and Anna Ing{\'o}lfsd{\'o}ttir}, pages={107--141}, journal=iandcomp, month={15~} # sep, year=1996, volume=129, number=2, abstract={In this paper, we present a general way of giving denotational semantics to a class of languages equipped with an operational semantics that fits the GSOS format of Bloom, Istrail, and Meyer. The canonical model used for this purpose will be Abramsky's domain of synchronization trees, and the denotational semantics automatically generated by our methods will be guaranteed to be fully abstract with respect to the finitely observable part of the bisimulation preorder. In the process of establishing the full abstraction result, we also obtain several general results on the bisimulation preorder (including a complete axiomatization for it), and give a novel operational interpretation of GSOS languages.}, references={IC::Abramsky1991, apal::Abramsky1991, MSCS::AbramskyV1993, tcs::Aceto1994, ic::AcetoBV1994, JACM::AcetoH1992, jacm::AptP1986, tcs::AustryB1984, tcs::Badoueld1991, TCS::Bloom1995, JACM::BloomIM1995, JACM::BolG1996:863, jacm::BrookesHR1984, ic::CleavelandH1990, focs::CourcelleN1976, tcs::NicolaH1984, ipl::Fokkink1994, jacm::goguenTWW1977, tcs::Groote1993, IC::GrooteV1992, ic::Hennessy1981, ic::Hennessy1983, jacm::Hennessy1985, ic::HennessyI1993, jacm::HennessyM1985, ipl::JifengH1993, LICS::Meyer1988, jacm::MilneM1979, tcs::Milner1977, jacm::Milner1979, tcs::Milner1983, ic::MilnerPW1992:1, ic::MilnerPW1992:41, sicomp::Plotkin1976, tcs::Plotkin1977, mscs::Rutten1992, tcs::Simone1985, jcss::Smyth1978, tcs::Stirling1987, tcs::Stoughton1988:317, lics::Ulidowski1992, lics::Vaandrager1991, ic::Walker1990} } Volume 130, Number 1 October 10, 1996 @Article{FennerFL96, refkey={C1613; PN2598}, title={Gap-Definability as a Closure Property}, author={Stephen Fenner and Lance Fortnow and Lide Li}, pages={1--17}, journal=iandcomp, month={10~} # oct, year=1996, volume=130, number=1, abstract={Gap-definability and the gap closure closure operator were defined by S.~Fenner, L.~Fortnow and S.~Kurth (\emph{J.~Comput.\ System Sci.}\ \textbf{48}, 116--148 (1994)). Few complexity classes were known at that time to be gap-definable. In this paper, we give simple characterizations of both gap-definability and the gap-closure operator, and we show that many complexity classes are gap-definable, including $\mathbf{P}^{\#\mathbf{P}}$, $\mathbf{P}^{\#\mathbf{P}[1]}$, \textbf{PSPACE}, \textbf{EXP}, \textbf{NEXP}, \textbf{MP} (Middle-bit~\textbf{P}), and $\mathbf{BP} \cdot \oplus \mathbf{P}$. If a class is closed under union and intersection and contains $\emptyset$ and $\Sigma^*$, then it is gap-definable if and only if it contains \textbf{SPP}; its gap-closure is the closure of this class together with \textbf{SPP} under union and intersection. On the other hand, we give some examples of classes which are reasonable and gap-definable but not closed under union (resp.\ intersection, complement). Finally, we show that a complexity class such as \textbf{PSPACE} or \textbf{PP}, if it is not equal to \textbf{SPP}, contains a maximal gap-definable many--one reduction-closed subclass, which is properly between \textbf{SPP} and the class of all \textbf{PSPACE}-incomplete (\textbf{PP}-incomplete) sets with respect to containment. The gap-closure of the class of all incomplete sets in \textbf{PSPACE} (resp.\ \textbf{PP}) is \textbf{PSPACE} (resp.\ \textbf{PP}).}, references={TCS::BeigelG1992, jcss::BeigelRS1995, IC::CaiH1989, mst::CaiH1990, jcss::FennerFK1994, sicomp::Gill1977, jcss::GreenKRST1995, tcs::Hertrampf1990, jacm::Ladner1975, THESIS::Simon1975, sicomp::TodaO1992, sicomp::Toda1991, tcs::Valiant1979, actai::Wagner1986} } @Article{JainS96, refkey={C1651; PN2596}, title={Computational Limits on Team Identification of Languages}, author={Sanjay Jain and Arun Sharma}, pages={19--60}, journal=iandcomp, month={10~} # oct, year=1996, volume=130, number=1, abstract={A team of learning machines is a multiset of learning machines. A team is said to successfully identify a concept just in case each member of some nonempty subset, of predetermined size, of the team identifies the concept. Team identification of programs for computable functions from their graphs has been investigated by Smith. Pitt showed that this notion is essentially equivalent to function identification by a single probabilistic machine. The present paper introduces, motivates, and studies the more difficult subject of team identification of grammars for languages from positive data. It is shown that an analog of Pitt's result about equivalence of team function identification and probabilistic language identification is strictly more powerful than team language identification. Proofs of many results in the present paper involve very sophisticated diagonalization arguments. Two very general tools are presented that yield proofs of new results from simple arithmetic manipulation of the parameters of known ones.}, references={IC::blumB1975, jacm::blum1967, ic::Fulk1990, sicomp::Gill1977, ic::Gold1967, tcs::JainS1995, ic::OshersonSW1986, ic::OshersonW1982, focs::Pitt1984, jacm::Pitt1989, ic::PittS1988, ic::PittS1988, focs::Smith1981, jacm::Smith1982} } @Article{WilkeY96, refkey={C1851; PN2599}, title={Computing the {Rabin} Index of a Regular Language of Infinite Words}, author={Thomas Wilke and Haiseung Yoo}, pages={61--70}, journal=iandcomp, month={10~} # oct, year=1996, volume=130, number=1, abstract={The Rabin index of a regular language of infinite words is the minimum number of accepting pairs used in any deterministic Rabin automaton recognizing this language. We show that the Rabin index of a language given by a Muller automaton with $n$ states and $m$ accepting sets is computable in time $O(m^2 nc)$ where $c$ is the cardinality of the alphabet.}, references={tcs::Barua1992, stacs::KrishnanPB1995, ic::McNaughton1966, focs::Safra1988, ic::Wagner1979} } @Article{AbdullaJ96:71, refkey={C1768; PN2602}, title={Undecidable Verification Problems for Programs with Unreliable Channels}, author={Parosh Aziz Abdulla and Bengt Jonsson}, pages={71--90}, journal=iandcomp, month={10~} # oct, year=1996, volume=130, number=1, abstract={We consider the class of finite-state systems communicating through unbounded by \emph{lossy} FIFO channels (called \emph{lossy channel systems}). These systems have infinite state spaces due to the unboundedness of the channels. In an earlier paper, we showed that the problems of checking reachability, safety properties, and eventuality properties are decidable for lossy channel systems. In this paper, we show that the following problems are undecidable: \begin{itemize} \item The \emph{model checking} problem in propositional temporal logics such as propositional linear time temporal logic (PTL) and computation tree logic (CTL). \item The problem of deciding \emph{eventuality properties with fair channels}: do all computations eventually reach a given set of states if the unreliable channels satisfy fairness assumptions? \end{itemize} The results are obtained through reduction from a variant of the Post correspondence problem.}, references={LICS::AlurCD1990, LICS::AbdullaJ1993, LICS::BurchCMDH1990, JACM::BrandZ1983, TOPLAS::ClarkeES1986, JACM::GermanS1992, TCS::Jancar1990, IC::JonssonP1993, TOPLAS::PengP1991, LICS::VardiW1986, POPL::Wolper1986} } @Article{DammH96, refkey={C1711; PN2603}, title={Inductive Counting for Width-Restricted Branching Programs}, author={Carsten Damm and Markus Holzer}, pages={91--99}, journal=iandcomp, month={10~} # oct, year=1996, volume=130, number=1, abstract={As an application of the inductive counting technique to a circuit-like model, we prove that complementation on nondeterministic branching programs can be done without increasing the width excessively. A consequence of this result is that the class of languages recognized by a generalization of nonuniform finite automata to nonconstant space is closed under complement.}, references={jcss::Barrington1989, tcs::BedardLM1993, sicomp::BorodinCDRT1989, jacm::ChandraKS1981, sicomp::Geffert1993, mst::IbarraR1988, sicomp::Immerman1988, mfcs::Lange1986, actai::Szelepcsenyi1988, stacs::Wagner1993}, preliminary={MFCS::DammH1994} } Volume 130, Number 2 November 1, 1996 @Article{BeameBRRT96, refkey={C1886; PN2600}, title={Time-Space Tradeoffs for Undirected Graph Traversal by Graph Automata}, author={Paul Beame and Allan Borodin and Prabhakar Raghavan and Walter L. Ruzzo and Martin Tompa}, pages={101--129}, journal=iandcomp, month={1~} # nov, year=1996, volume=130, number=2, abstract={We investigate time-space tradeoffs for traversing undirected graphs, using a variety of structured models that are all variants of Cook and Rackoff's ``Jumping Automata for Graphs.'' Our strongest tradeoff is a quadratic lower bound on the product of time and space for graph traversal. For example, achieving linear time requires linear space, implying that depth-first search is optimal. Since our bound in fact applies to nondeterministic algorithms for \emph{non}connectivity, it also implies that closure under complementation of nondeterministic space-bounded complexity classes is achieved only at the expense of increased time. To demonstrate that these structured models are realistic, we also investigate their power. In addition to admitting well known algorithms such as depth-first search and random walk, we show that one simple variant of this model is nearly as powerful as a Turing machine. Specifically, for general undirected graph problems, it can simulate a Turing machine with only a constant factor increase in space and a polynomial factor increase in time.}, references={focs::Adleman1978:75, focs::AleliunasKLLR1979, sicomp::Bar-NoyBKLW1989, sctc::BarnesBRS1992, sicomp::BarnesBRS1998, focs::BarnesE1993, stoc::BarnesF1993, stoc::BarnesR1991, focs::BeameBRRT1990, sicomp::BeameBRRT1998, focs::BermanS1983, focs::BlumK1978, focs::blumS1977, sicomp::BorodinCDRT1989, jcss::BorodinRT1992:180, jalgo::Bridgland1987, sicomp::BroderKRU1994, ic::BussT1995, stoc::ChandraRRST1989, sicomp::CookR1980, stoc::Edmonds1993, stoc::EdmondsP1995, focs::Feige1993, sicomp::Immerman1988, stoc::Istrail1988, focs::Istrail1990, stoc::Kurshan1994, focs::NisanSW1992, jcss::Savitch1970, jcss::Savitch1973, actai::Szelepcsenyi1988, sicomp::Tompa1982, sicomp::Tompa1992} } @Article{Wang96, refkey={C1725; PN2607}, title={Parametric Timing Analysis for Real-Time Systems}, author={Farn Wang}, pages={131--150}, journal=iandcomp, month={1~} # nov, year=1996, volume=130, number=2, abstract={We extend a TCTL model-checking problem to a parametric timing analysis problem for real-time systems and develop new techniques for solving it. The algorithm we present here accepts timed transition system descriptions and parametric TCTL formulas with timing parameter variables of unknown sizes and can give back general linear equations of timing parameter variables whose solutions make the systems work.}, references={IC::AlurCD1993:2, lics::AlurH1990, stoc::AlurHV1993, lics::BurchCMDH1990, toplas::ClarkeES1986, lics::HarelLP1990:402, lics::HenzingerNSY1992, lics::Lewis1990, focs::Pnueli1977, ACMTOSEM::WangME1993}, preliminary={LICS::Wang1995:112} } @Article{GiancarloG96, refkey={C1593; PN2608}, title={On the Construction of Classes of Suffix Trees for Square Matrices: Algorithms and Applications}, author={Raffaele Giancarlo and Roberto Grossi}, pages={151--182}, journal=iandcomp, month={1~} # nov, year=1996, volume=130, number=2, abstract={We provide a uniform framework for the study of index data structures for a two-dimensional matrix $\mathit{TEXT}[1:n, 1:n]$ whose entries are drawn from an ordered alphabet~$\Sigma$. An index for $\mathit{TEXT}$ can be informally seen as a two-dimensional analog of the suffix tree for a string. It allows on-line searches and statistics to be performed on $\mathit{TEXT}$ by representing compactly the $\Theta(n^3)$ square submatrices of $\mathit{TEXT}$ in optimal $O(n^2)$ space. We identify $4^{n - 1}$ families of indices for $\mathit{TEXT}$, each containing $\prod_{i=1}^n (2i - 1)!$ isomorphic data structures. We also develop techniques leading to a single algorithm that efficiently builds any index in any family in $O(n^2 \log n)$ time and $O(n^2)$ space. Such an algorithm improves in various respects the algorithms for the construction of the PAT tree and the Lsuffix tree. The framework and algorithm easily generalize to $d > 2$ dimensions. Moreover, as part of our algorithm, we provide new algorithmic tools that yield a space-efficient implementation of the ``naming scheme'' of R.~Karp \emph{et al.}\ (\emph{in} ``Proceedings, Fourth Symposium on Theory of Computing,'' pp.~125--136) for strings and matrices.}, references={ipl::AmirF1992:233, ic::AmirF1995:1, tcs::AmirL1991:97, jalgo::AmirLV1992:2, algor::ApostolicoILSV1988:347, actai::BayerM1972:173, algor::ChangL1994:327, tcs::CrochemoreR1991:59, sicomp::GalilP1990:989, wads::Giancarlo1993:337, sicomp::Giancarlo1995:520, spaa::GiancarloG1993:86, focs::GuibasS1978:8, sicomp::HarelT1984:338, ic::IduryS1995:78, stoc::KarpMR1972:125, jalgo::LandauV1989:157, sicomp::ManberM1993:935, jacm::McCreight1976:262, sicomp::SchieberV1988:1253} } @Article{BruyereF96, refkey={C1852; PN2604}, title={Any Lifting of a Trace Coding Is a Word Coding}, author={V{\'e}ronique Bruy{\`e}re and Clelia De Felice}, pages={183--193}, journal=iandcomp, month={1~} # nov, year=1996, volume=130, number=2, abstract={A trace coding is an injective morphism between two trace monoids. This definition naturally extends the classical notion of word coding between two free monoids. We prove that any lifting of a trace coding is a word coding. More precisely, given a trace coding~$F$, let us choose for any letter~$a$, a representative~$f(a)$ of the trace~$F(a)$. Then, the word morphism~$f$ is also a coding. This result positively solves a problem proposed by Ochma{\'n}ski.}, references={mst::AalbersbergH1989:1, tcs::BruyereFG1995, tcs::CoriM1985, tcs::Duboc1986} } Volume 131, Number 1 November 25, 1996 @Article{FerrucciPSSTTV96, refkey={C1750; PN2597}, title={Symbol--Relation Grammars: A Formalism for Graphical Languages}, author={F. Ferrucci and G. Pacini and G. Satta and M. I. Sessa and G. Tortora and M. Tucci and G. Vitiello}, pages={1--46}, journal=iandcomp, month={25~} # nov, year=1996, volume=131, number=1, abstract={A common approach to the formal description of pictorial and visual languages makes use of formal grammars and rewriting mechanisms. The present paper is concerned with the formalism of Symbol--Relation Grammars (SR grammars, for short). Each sentence in an SR language is composed of a set of symbol occurrences representing visual elementary objects, which are related through a set of binary relational items. The main feature of SR grammars is the uniform way they use context-free productions to rewrite symbol occurrences as well as relation items. The clearness and uniformity of the derivation process for SR grammars allow the extension of well-established techniques for syntactic and semantic analysis to the case of SR grammars. The paper provides an accurate analysis of the derivation mechanism and the expressive power of the SR formalism. This is necessary to fully exploit the capabilities of the model. The most meaningful features of SR grammars as well as their generative power are compared with those of well-known graph grammar families. In spite of their structural simplicity, variations of SR grammars have a generative power comparable with that of expressive classes of graph grammars, such as the edNCE and the N-edNCE classes.}, references={ieeetse::AngelaccioCS1990, tcs::Barbar1993, ieeetse::Chang1990, tcs::Courcelle1987, ieeetse::CrimiGPTT1990, tcs::EhrenfeuchtMR1984:211, actai::EngelfrietF1981, jcss::EngelfrietLW1990, ic::EngelfrietL1989, scp::Harel1987, ieeetse::HirakawaTI1990, is::JanssensR1980:191, is::JanssensR1980:217, is::KreowskiR1990:185, is::KreowskiR1990:221, ic::Penttonen1974, ic::RozenbergW1986, ieeetse::TucciVC1994, is::YamazakiY1993} } @Article{KariT96, refkey={C1903; PN2606}, title={Contextual Insertions/Deletions and Computability}, author={Lila Kari and Gabriel Thierrin}, pages={47--61}, journal=iandcomp, month={25~} # nov, year=1996, volume=131, number=1, abstract={We investigate two generalizations of insertion and deletion of words, that have recently become of interest in the context of molecular computing. Given a pair of words $(x, y)$, called a \emph{context}, the $(x, y)$-contextual insertion of a word~$w$ into a word~$u$ is performed as follows. For each occurrence of~$xy$ as a subword in~$u$, we include in the result of the contextual insertion the words obtained by inserting~$v$ into~$u$, between $x$ and~$y$. The $(x, y)$-contextual deletion operation is defined in a similar way. We study closure properties of the Chomsky families under the defined operations, contextual ins-closed and del-closed languages, and decidability of existence of solutions to equations involving these operations. Moreover, we prove that every Turing machine can be simulated by a system based entirely on contextual insertions and deletions.}, references={tcs::Kari1994} } @Article{KaoRT96, refkey={C1336; PN2605}, title={Searching in an Unknown Environment: An Optimal Randomized Algorithm for the Cow-Path Problem}, author={Ming-Yang Kao and John H. Reif and Stephen R. Tate}, pages={63--79}, journal=iandcomp, month={25~} # nov, year=1996, volume=131, number=1, abstract={Searching for a goal is a central and extensively studied problem in computer science. In classical searching problems, the cost of a search function is simply the number of queries made to an oracle that knows the position of the goal. In many robotics problems, as well as in problems from other areas, we want to charge a cost proportional to the distance between queries (e.g., the time required to travel between two query points). With this cost function in mind, the abstract problem known as the $w$-lane cow-path problem was designed. There are known optimal deterministic algorithms for the cow-path problem; we give the first randomized algorithm in this paper. We show that our algorithm is optimal for two paths ($w = 2$) and give evidence that it is optimal for larger values of~$w$. Subsequent to the preliminary version of this paper, Kao \emph{et al}.\ (in ``Proceedings, 5th ACM--SIAM Symposium on Discrete Algorithm,'' pp.~372--381, 1994) have shown that our algorithm is indeed optimal for all~$w \ge 2$. Our randomized algorithm gives expected performance that is almost twice as good as is possible with a deterministic algorithm. For the performance of our algorithm, we also derive the asymptotic growth with respect to~$w$---despite similar complexity results for related problems, it appears that this growth has never been analyzed.}, references={stoc::AslamD1991:486, ic::Baeza-YatesCR1993:234, ipl::BentleyY1976:82, stoc::BlumRS1991:494, focs::DengP1990:355, focs::FiatFKRRV1991:288, focs::FiatRR1990:454, soda::KaoMSY1994:372, soda::KaoRT1993:441, tcs::PapadimitriouY1991:127, jcss::RivestMKWS1980:396, cacm::SleatorT1985:202, focs::Yao1977:222} } @Article{Bertram-KretzbergH96, refkey={C1783; PN2609}, title={Multiple Product Modulo Arbitrary Numbers}, author={Claudia Bertram-Kretzberg and Thomas Hofmeister}, pages={81--93}, journal=iandcomp, month={25~} # nov, year=1996, volume=131, number=1, abstract={Let $n$ binary numbers of length~$n$ be given. The Boolean function ``Multiple Product''~$\mathit{MP}_n$ asks for (some binary representation of) the value of their product. It has been shown (K.-Y.~Siu and V.~Rowchowdhury, On optimal depth threshold circuits for multiplication and related problems, \emph{SIAM J.~Discrete Math}.\ \textbf{7}, 285--292 (1994)) that this function can be computed in polynomial-size threshold circuits of depth~4. For many other arithmetic functions, circuits of depth~3 are known. They are mostly based on the fact that the value of the considered function modulo some prime numbers~$p$ can be computed easily in threshold circuits of depth~2. In this paper, we investigate the complexity of computing $\mathit{MP}_n$ modulo~$m$ by depth-2 threshold circuits. It turns out that for all but a few integers~$m$, exponential size is required. In particular, it is shown that for $m \in \{2, 4, 8\}$, polynomial-size circuits exist, for $m \in \{3, 6, 12, 24\}$, the question remains open and in all other cases, exponential-size circuits are required. The result still holds if we allow $m$ to grow with~$n$.}, references={jcss::HajnalMPST1993, stoc::GoldmannK1993, stacs::Krause1995:83, mst::KrauseW1995, ipl::Wegener1993} } Volume 131, Number 2 December 15, 1996 @Article{RoossW96, refkey={C1749}, title={On the Power of {DNA}-Computing}, author={Diana Roo{\ss} and Klaus W. Wagner}, pages={95--109}, journal=iandcomp, month={15~} # dec, year=1996, volume=131, number=2, abstract={Adleman used biological manipulations with DNA strings to solve some instances of the Directed Hamiltonian Path Problem. Lipton showed how to extend this idea to solve any NP problem. We prove that exactly the problems in $\mathrm{P}^{\mathrm{NP}} = \Delta^{\mathrm{p}}_2$ can be solved in polynomial time using Lipton's model. Various modifications of Lipton's model, based on other DNA manipulations, are investigated systematically, and it is proved that their computational power in polynomial time can be characterized by one of the complexity classes~$\mathrm{P}$, $\Delta^{\mathrm{p}}_2$, or $\Delta^{\mathrm{p}}_3$.}, references={stoc::BernsteinV1993, focs::Shor1994, sctc::Pudlak1994} } @Article{BlundoSV96, refkey={C1800; PN2610}, title={Randomness in Distribution Protocols}, author={Carlo Blundo and Alfredo De Santis and Ugo Vaccaro}, pages={111--139}, journal=iandcomp, month={15~} # dec, year=1996, volume=131, number=2, abstract={Randomness is a useful computation resource due to its ability to enhance the capabilities of other resources. Its interaction with resources such as time, space, interaction with provers and its role in several areas of computer science has been extensively studied. In this paper we give a systematic analysis of the amount of randomness needed by secret sharing schemes and secure key distribution schemes. We give both upper and lower bounds on the number of random bits needed by secret sharing schemes. The bounds are tight for several classes of secret sharing schemes. For secure key distribution schemes we provide a lower bound on the amount of randomness needed, thus showing the optimality of a recently proposed key distribution protocol.}, references={focs::AroraLMSS1992, focs::BellareGS1995, stoc::BellareS1994, stoc::Ben-OrGW1988, tcs::BlundoSGV1996, jcrypt::BlundoSSV1995, jcrypt::BrickellD1991, jcrypt::BrickellS1992, jcrypt::CapocelliSGV1993:157, stoc::FeigeK1994, stoc::FranklinY1992, stoc::GoldreichMW1987, jcrypt::GongW1990, focs::Hastad1996, focs::ImpagliazzoZ1989:248, stoc::KrizancPU1988, jacm::Rabin1989, jcrypt::TompaW1988, focs::Zuckerman1991} } @Article{Sangiorgi96, refkey={C1781}, title={Bisimulation for Higher-Order Process Calculi}, author={Davide Sangiorgi}, pages={141--178}, journal=iandcomp, month={15~} # dec, year=1996, volume=131, number=2, abstract={A \emph{higher-order process calculus} is a calculus for communicating systems which contains higher-order constructions like communication of terms. We analyse the notion of \emph{bisimulation} in these calculi. We argue that both the standard definition of bisimulation (i.e., the one for CCS and related calculi), as well as \emph{higher-order bisimulation} [E.~Astesiano, A.~Giovini, and G.~Reggio, \emph{in} ``STACS~'88,'' Lecture Notes in Computer Science, Vol.~294, pp.~207--226, Springer-Verlag, Berlin/New York, 1988; G.~Boudol, \emph{in} ``TAPSOFT~'89,'' Lecture Notes in Computer Science, Vol.~351, pp.~149--161, Springer-Verlag, Berlin/New York, 1989; B.~Thomsen, Ph.D.\ thesis, Dept.\ of Computing, Imperial College, 1990] are in general unsatisfactory, because of their over-discrimination. We propose and study a new form of bisimulation for such calculi, called \emph{context bisimulation}, which yields a more satisfactory discriminating power. A drawback of context bisimulation is the heavy use of universal quantification in its definition, which is hard to handle in practice. To resolve this difficulty we introduce \emph{triggered bisimulation} and \emph{normal bisimulation}, and we prove that they both coincide with context bisimulation. In the proof, we exploit the \emph{factorisation theorem}: When comparing the behaviour of two processes, it allows us to ``isolate'' subcomponents which might give differences, so that the analysis can be concentrated on them.}, references={stacs::AstesianoGR1988, tcs::AstesianoGR1992, facs::BoudolCHK1994, jacm::CastellaniH1989, lics::Hennessy1993, ic::MilnerPW1992:1, ic::MilnerPW1992:41, ic::ParrowS1995, tcs::Sangiorgi1996, actai::Thomsen1993} } @Article{AgrawalA96, refkey={C1904; PN2611}, title={A Note on Decision versus Search for Graph Automorphism}, author={M. Agrawal and V. Arvind}, pages={179--189}, journal=iandcomp, month={15~} # dec, year=1996, volume=131, number=2, abstract={We show that for any graph~$G$, $k$ nontrivial automorphisms of~$G$---if as many exist---can be computed in time~$|G|^{O(\log k)}$ with nonadaptive queries to~GA, the decision problem for Graph Automorphism. As a consequence, we show that some problems related to~GA are actually polynomial-time truth-table equivalent to~GA\@. One of these results provides an answer to an open question of Lubiw [\emph{SIAM J.\ Comput.}\ \textbf{10} (1981), 11--21].}, references={jacm::blumK1995, sicomp::Lubiw1981, ipl::Mathon1979, jcss::Schoning1988} } Volume 132, Number 1 January 10, 1997 @Article{KivinenW97, refkey={C1887}, title={Exponentiated Gradient Versus Gradient Descent for Linear Predictors}, author={Jyrki Kivinen and Manfred K. Warmuth}, pages={1--63}, journal=iandcomp, month={10~} # jan, year=1997, volume=132, number=1, preliminary={stoc::KivinenW1995}, abstract={We consider two algorithms for on-line prediction based on a linear model. The algorithms are the well-known gradient descent (GD) algorithm and a new algorithm, which we call $\mathrm{EG}^\pm$. They both maintain a weight vector using simple updates. For the GD algorithm, the update is based on subtracting the gradient of the squared error made on a prediction. The $\mathrm{EG}^\pm$ algorithm uses the components of the gradient in the exponents of factors that are used in updating the weight vector multiplicatively. We present worst-case loss bounds for $\mathrm{EG}^\pm$ and compare them to previously known bounds for the GD algorithm. The bounds suggest that the losses of the algorithms are in general comparable, but $\mathrm{EG}^\pm$ has a much smaller loss if only a few components of the input are relevant for the predictions. We have performed experiments which show that our worst-case upper bounds are quite tight already on simple artificial data.}, references={tr::Amari1994, NC::Amari1995, colt::BoserGV1992, stoc::Cesa-BianchiFHHSW1993, TR::Cesa-BianchiFHHSW1994, IEEETNN::Cesa-BianchiLW1995, jrss::DempsterLR1977, tr::HausslerKW1994, misc::HelmboldKW1996, ml::HelmboldSSW1996, icml::HelmboldSSW1996, jcss::HelmboldW1995, ccss::Hinton1986, ml::KearnsSS1994, ml::Littlestone1988, colt::Littlestone1989, thesis::Littlestone1989, colt::Littlestone1991, jcc::LittlestoneLW1995, ic::LittlestoneW1994, icml::SchapireW1994, colt::Vovk1990} } @Article{JainS97, refkey={C1928}, title={Elementary Formal Systems, Intrinsic Complexity, and Procrastination}, author={Sanjay Jain and Arun Sharma}, pages={65--84}, journal=iandcomp, month={10~} # jan, year=1997, volume=132, number=1, abstract={Recently, rich subclasses of elementary formal systems (EFS) have been shown to be identifiable in the limit from only positive data. Examples of these classes are Angluin's pattern languages, unions of pattern languages by Wright and Shinohara, and classes of languages definable by length-bounded elementary formal systems studied by Shinohara. The present paper employs two distinct bodies of abstract studies in the inductive inference literature to analyze the learnability of these concrete classes. The first approach uses constructive ordinals to bound the number of mind changes. $\omega$ denotes the first limit ordinal. An ordinal mind change bound of~$\omega$ means that identification can be carried out by a learner that after examining some element(s) of the language announces an upper bound on the number of mind changes it will make before converging; a bound of~$\omega \cdot 2$ means that the learner reserves the right to revise this upper bound once; a bound of~$\omega \cdot 3$ means the learner reserves the right to revise this upper bound twice, and so on. A bound of~$\omega^2$ means that identification can be carried out by a learner that announces an upper bound on the number of times it may revise its conjectured upper bound on the number of mind changes. It is shown in the present paper that the ordinal mind change complexity for identification of languages formed by unions of up to $n$ pattern languages is~$\omega^n$. It is also shown that this bound is essential. Similar results are also shown to hold for classes definable by length-bounded elementary formal systems with up to $n$ clauses. The second approach employs reductions to study the intrinsic complexity of learnable classes. It is shown that the class of languages formed by taking unions of up to $n + 1$ pattern languages is a strictly more difficult learning problem than the class of languages formed by the union of up to $n$ pattern languages. It is also shown that a similar hierarchy holds for the bound on the number of clauses in the case of languages definable by length-bounded EFS.b\@. In addition to building bridges between three distinct areas of inductive inference, viz., learnability of EFS subclasses, ordinal mind change complexity, and intrinsic complexity, this paper also presents results that relate topological properties of learnable classes to that of intrinsic complexity and ordinal mind change complexity. For example, if is shown that a class that is complete according to the reductions for intrinsic complexity has infinite elasticity. Since EFS languages and their learnability results have counterparts in traditional logic programming, the present paper demonstrates the possibility of using abstract results of inductive inference to gain insights into inductive programming.}, references={ieicetis::ArikawaMSSY1992, jcss::Angluin1980, misc::Arikawa1970, misct::Arimura1989, misc::ArimuraS1994, lnai::ArikawaSMS1991, tcs::ArikawaSY1992, jacm::Blum1967, lnai::CaseJS1995, ecclt::FreivaldsKS1995, colt::FreivaldsS1992:363, ic::FreivaldsS1993, ic::Gold1967, colt::JainS1994, eurocolt::JainS1995, jcss::JainS1996:393, jsyml::JainS1996, jsyml::Kleene1938, iwalt::Rao1996, colt::MotokiSW1991, thesis::Shinohara1986, ngc::Shinohara1991, ic::Shinohara1994, book::Smullyan1961, colt::Wright1989} } Volume 132, Number 2 February 1, 1997 @Article{JansenO1997, refkey={C1794; PN2616}, title={Approximation Algorithms for Time Constrained Scheduling}, author={Klaus Jansen and Sabine {\"O}hring}, pages={85--108}, journal=iandcomp, month={1~} # feb, year=1997, volume=132, number=2, abstract={In this paper we consider the following time constrained scheduling problem. Given a set of jobs~$J$ with execution times $e(j) \in (0, 1]$ and an undirected graph $G = (J, E)$, we consider the problem to find a schedule for the jobs such that adjacent jobs $(j, j') \in E$ are assigned to different machines and that the total execution time for each machine is at most~1. The goal is to find a minimum number of machines to execute all jobs under this time constraint. This scheduling problem is a natural generalization of the classical bin-packing problem. We propose and analyse several approximation algorithms with constant absolute worst case ratio for graphs that can be colored in polynomial time.}, references={tcs::BakerC1996, mfcs::BodlaenderJ1993, soda::IraniL1996, sicomp::JohnsonDUGG1974, stoc::LundY1993} } @Article{TofteT1997, refkey={C1753}, title={Region-Based Memory Management}, author={Mads Tofte and Jean-Pierre Talpin}, pages={109--176}, journal=iandcomp, month={1~} # feb, year=1997, volume=132, number=2, abstract={This paper describes a memory management discipline for programs that perform dynamic memory allocation and de-allocation. At runtime, all values are put into \emph{regions}. The store consists of a stack of regions. All points of region allocation and de-allocation are inferred automatically, using a type and effect based program analysis. The scheme does not assume the presence of a garbage collector. The scheme was first presented in 1994 (M.~Tofte and J.-P. Talpin, \emph{in} ``Proceedings of the 21st ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages,'' pp.~188--201); subsequently, it has been tested in the ML Kit with Regions, a region-based, garbage-collection free implementation of the Standard ML Core Language, which includes recursive datatypes, higher-order functions and updatable references (L.~Birkedal, M.~Tofte, and M.~Vejlstrup, (1996), \emph{in} ``Proceedings of the 23rd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages,'' pp.~171--183). This paper defines a region-based dynamic semantics for a skeletal programming language extracted from Standard ML\@. We present the inference system which specifies where regions can be allocated and de-allocated and a detailed proof that the system is sound with respect to a standard semantics. We conclude by giving some advice on how to write programs that run well on a stack of regions, based on practical experience with the ML Kit.}, references={pldi::AikenFL1995, book::Appel1992, CACM::Baker1978, clfp::Baker1990, popl::BirkedalTV1996, TR::GiffordJS1987, POPL::DamasM1982, MISC::Dijkstra1960, MISC::ElsmanH1995, toplas::Georgeff1984, clfp::Hudak1986, popl::JouvelotG1991, toplas::InoueSY1988:555, book::Knuth1972, cacm::LiebermanH1983, popl::LucassenG1988, thesis::Lucassen1987, jcss::Milner1978, book::MilnerTH1990, lncs::Mycroft1984, cacm::Backus+1963:1, popl::RuggieriM1988, thesis::Talpin1993, jfp::TalpinJ1992, TR::TofteT1993, popl::TofteT1994}, preliminary={POPL::TofteT1994} } Volume 133, Number 1 February 25, 1997 @Article{HromkovicKUW1997, refkey={C1872; PN2618}, title={Optimal Algorithms for Broadcast and Gossip in the Edge-Disjoint Path Modes}, author={Juraj Hromkovi{\v{c}} and Ralf Klasing and Walter Unger and Hubert Wagener}, pages={1--33}, journal=iandcomp, month={25~} # feb, year=1997, volume=133, number=1, abstract={The communication power of the one-way and two-way edge-disjoint path modes for broadcast and gossip is investigated. The complexity of communication algorithms is measured by the number of communication steps (rounds). The main results achieved are the following: \begin{enumerate} \item For each connected graph~$G_n$ of $n$ nodes, the complexity of broadcast in~$G_n$, $B_{\mathrm{min}}(G_n)$, satisfies $\lceil \log_2 n\rceil \le B_{\mathrm{min}} \le \lceil \log_2 n\rceil + 1$. The complete binary trees meet the upper bound, and all graphs containing a Hamiltonian path meet the lower bound. \item For each connected graph~$G_n$ of $n$ nodes, the one-way (two-way) gossip complexity $R(G_n)$ ($R^2(G_n)$) satisfies \begin{align*} \lceil \log_2 n\rceil &\le R^2(G_n) \le 2 \cdot \lceil \log_2 n\rceil + 1,\\ 1.44\ldots \log_2 n &\le R(G_n) \le 2 \cdot \lceil \log_2 n\rceil + 2. \end{align*} All these lower and upper bounds are shown to be sharp up to~1. \item All planar graphs of $n$ nodes and degree~$h$ have a two-way gossip complexity of at least $1.5 \log_2 n - \log_2 \log_2 n - 0.5 \log_2 h - 8$, and the two-dimensional grid of $n$ nodes has the gossip complexity $1.5 \log_2 n - \log_2 \log_2 n \pm O(1)$; i.e., two-dimensional grids are optimal gossip structures among planar graphs of bounded degree. Some upper bounds are also obtained for the one-way mode. \item The $d$-dimensional grid, $d \ge 3$, of $n$ nodes has the two-way gossip complexity $(1 + 1/d) \cdot \log_2 n - \log_2 n \log_2 n \pm O(d)$. \end{enumerate}}, references={ipl::BagchiHMS1990, jalgo::DiksDSV1993, algor::HromkovicJM1993, ic::HromkovicKSW1995, sicomp::KrummeCV1992, focs::KahnKL1988} } @Article{Sorensen1997, refkey={C1883; PN2622}, title={Strong Normalization from Weak Normalization in Typed {$\lambda$}-Calculi}, author={Morten Heine S{\o}rensen}, pages={35--71}, journal=iandcomp, month={25~} # feb, year=1997, volume=133, number=1, abstract={For some typed $\lambda$-calculi it is easier to prove weak normalization than strong normalization. Techniques to infer the latter from the former have been invented over the last twenty years by Nederpelt, Klop, Khasidashvili, Karr, de~Groote, and Kfoury and Wells. However, these techniques infer strong normalization of one notion of reduction from weak normalization of a \emph{more complicated} notion of reduction. This paper presents a new technique to infer strong normalization of a notion of reduction in a typed $\lambda$-calculus from weak normalization of the \emph{same} notion of reduction. The technique is demonstrated to work on some well-known systems including second-order $\lambda$-calculus and the system of positive, recursive types. It gives hope for a positive answer to the Barendregt--Geuvers conjecture stating that every pure type system which is weakly normalizing is also strongly normalizing. The paper also analyzes the relationship between the techniques mentioned above, and reviews, in less detail, other techniques for proving strong normalization.}, references={popl::AriolaFMOW1995, ic::BlooKN1996, jfp::CoquandH1994, jsyml::Vrijer1985, popl::Filinski1994, popl::Griffin1990, popl::HarperL1993, jsyml::Howard1980, tcs::KamareddineN1994:183, jfp::KamareddineN1995, tcs::KamareddineN1996, ic::KfouryT1992, jacm::KfouryTU1994, stacs::Khasidashvili1994, tcs::KlopOR1993, jsyml::Leivant1985, jfp::Mitchell1991, lics::Moggi1989, ic::Moggi1991, tcs::Plotkin1975, tcs::Regnier1994, jsyml::Tait1967, mfcs::Urzyczyn1995} } Volume 133, Number 2 March 15, 1997 @Article{BakelF1997, refkey={C1763; PN2617}, title={Normalization Results for Typeable Rewrite Systems}, author={Steffen van Bakel and Maribel Fern{\'a}ndez}, pages={73--116}, journal=iandcomp, month={15~} # mar, year=1997, volume=133, number=2, abstract={In this paper we introduce Curryfied term rewriting systems, and a notion of partial type assignment on terms and rewrite rules that uses intersection types with sorts and~$\omega$. Three operations on types---substitution, expansion, and lifting---are used to define type assignment and are proved to be sound. With this result the system is proved closed for reduction. Using a more liberal approach to recursion, we define a general scheme for recursive definitions and prove that, for all systems that satisfy this scheme, every term typeable without using the type-constant~$\omega$ is strongly normalizable. We also show that, under certain restrictions, all typeable terms have a (weak) head-normal form, and that terms whose type does not contain~$\omega$ are normalizable.}, references={tacs::AriolaKKSV1994, tcs::Bakel1992, jlogc::Bakel1993, tcs::Bakel1995, lics::BarbaneraFG1994, jsyml::BarendregtCD1983, ndjfl::CoppoD1980, tcs::Dezani-CiancagliniH1992, popl::FutatsugiGJM1985, lics::JouannaudO1991, jsymc::Kahrs1996, jsymc::KennawayKSV1996, jcss::Milner1978} } @Article{Jutla1997, refkey={C1650; PN2624}, title={Determinization and Memoryless Winning Strategies}, author={Charanjit S. Jutla}, pages={117--134}, journal=iandcomp, month={15~} # mar, year=1997, volume=133, number=2, abstract={We show that Safra's determinization of $\omega$-automata with Streett (strong fairness) acceptance condition also gives memoryless winning strategies in infinite games, for the player whose acceptance condition is the complement of the Streett condition. Both determinization and memorylessness are essential parts of known proofs of Rabin's tree automata complementation lemma. Also, from Safra's determinization construction, along with its memoryless winning strategy extension, a single exponential construction and proof first appeared in [N.~Klarlund (1992), Progress measures, immediate determinacy, and a subset construction for tree automata, \emph{in} ``Proceedings, 7th IEEE Symposium on Logics in Computer Science''].}, references={jsyml::Buchi1983, stoc::EmersonH1982, focs::EmersonJ1988, focs::EmersonJ1991, ic::EmersonS1984, stoc::GurevichH1982, lics::Klarlund1992, ic::McNaughton1966, tcs::MullerS1987:267, focs::Safra1988, stoc::Safra1992} } Volume 134, Number 1 April 10, 1997 @Article{DoniniLNN1997, refkey={C1814; PN2625}, title={The Complexity of Concept Languages}, author={Francesco M. Donini and Maurizio Lenzerini and Daniele Nardi and Werner Nutt}, pages={1--58}, journal=iandcomp, month={10~} # apr, year=1997, volume=134, number=1, abstract={A basic feature of Terminological Knowledge Representation Systems is to represent knowledge by means of taxonomies, here called terminologies, and to provide a specialized reasoning engine to do inferences on these structures. The taxonomony is built through a representation language called a \emph{concept language} (or \emph{description logic}), which is given a well-defined set-theoretic semantics. The efficiency of reasoning has often been advocated as a primary motivation for the use of such systems. The main contributions of the paper are: (1)~a complexity analysis of concept satisfiability and subsumption for a wide class of concept languages; (2)~algorithms for these inferences that comply with the worst-case complexity of the reasoning task they perform.}, references={AI::BaaderFHNP1994, SIGART::BaaderH1991, BOOK::BellM1977, misc::Brachman1979, AIM::Brachman1985, ICPKRR::Brachman1992, IEEEC::BrachmanFL1983, AAAI::BrachmanL1984, BOOK::BrachmanL1985, COGSCI::BrachmanS1985, JLOGC::HoekR1995:325, AI::DoniniHLSNN1992, IJCAI::DoniniLNN1991, BOOK::Fitting1990, BOOK::GareyJ1979, AI::HalpernM1992, AI::HeinsohnKNP1994, TR::HollunderN1990, TR::HollunderN1995, ECAI::HollunderNS1990, HTCS::Johnson1990, HTCS::Kanellakis1990, sicomp::Ladner1977, AI::Levesque1984, COMPI::LevesqueB1987, MISC::Lipkis1982, AI::Nebel1988, AI::Nebel1990, THESIS::Nutt1993, AI::Patel-Schneider1989, MISC::Patel-SchneiderS1993, TR::Schild1988, IJCAI::Schild1991, ICPKRR::Schmidt-Schauss1989, AI::Schmidt-SchaussS1991, MISC::SchmolzeB1982, TR::Smolka1988, BOOK::Smullyan1968, MISC::Woods1975, MISC::WoodsS1992} } @Article{GoreJKSM1997, refkey={C1840; PN2621}, title={A Quasi-polynomial-time Algorithm for Sampling Words from a Context-Free Language}, author={Vivek Gore and Mark Jerrum and Sampath Kannan and Z. Sweedyk and Steve Mahaney}, pages={59--74}, journal=iandcomp, month={10~} # apr, year=1997, volume=134, number=1, abstract={A quasi-polynomial-time algorithm is presented for sampling almost uniformly at random from the $n$-slice of the language~$L(G)$ generated by an arbitrary context-free grammer~$G$. (The $n$-slice of a language~$L$ over an alphabet~$\Sigma$ is the subset~$L \cup \Sigma^n$ of words of length exactly~$n$.) The time complexity of the algorithm is $\epsilon^{-2}(n |G|)^{O(\log n)}$ where the parameter~$\epsilon$ bounds the variation of the output distribution from uniform, and~$|G|$ is a natural measure of the size of grammar~$G$. The algorithm applies to a class of language sampling problems that includes slices of context-free languages as a proper subclass. For the restricted case of homogenous languages expressed by regular expressions without Kleene-star, a truly polynomial-time algorithm is presented.}, references={stoc::AllenderJ1993, jacm::GinsburgU1966, sicomp::HickeyC1983, tcs::JerrumVV1986, soda::KannanSM1995, focs::KarpL1983, jalgo::KarpLM1989, ipl::Mairson1994, stoc::Nisan1991, sicomp::ValiantSBR1983} } Volume 134, Number 2 May 1, 1997 @Article{LarsenW1997, refkey={C1550; PN2623}, title={Time-Abstracted Bisimulation: Implicit Specifications and Decidability}, author={Kim G. Larsen and Yi Wang}, pages={75--101}, journal=iandcomp, month={1~} # may, year=1997, volume=134, number=2, abstract={In the last few years a number of real-time process calculi have emerged with the purpose of capturing important quantitative aspects of real-time systems. In addition, a number of process equivalences sensitive to time-quantities have been proposed, among these the notion of timed (bisimulation) equivalence. In this paper, we introduce a \emph{time-abstracting} (bisimulation) equivalence and investigate its properties with respect to the real-time process calculus of Wang (Real-time behaviour of asynchronous agents, \emph{in} ``Proceedings of CONCUR'90,'' Lecture Notes in Computer Science, Vol.~458, Springer-Verlag, Berlin/New York, 1990). Seemingly, such an equivalence would yield very little information (if any) about the timing properties of a process. However, time-abstracted reasoning about a composite process may yield important information about the relative timing-properties of the components of the system. In fact, we show as a main theorem that such implicit reasoning will reveal \emph{all} timing aspects of a process. More precisely, we prove that two processes are interchangeable in any context up to time-abstracted equivalence precisely if the two processes are themselves timed equivalent. As our second main theorem, we prove that time-abstracted equivalence is decidable for the calculus of Wang, using classical methods based on a finite-state symbolic, structured operational semantics.}, references={ic::AlurCD1993, tcs::AlurD1994, ic::HenzingerNSY1994, ic::KanellakisS1990, actai::NicollinSY1993} } @Article{GalilM1997, refkey={C1393; PN2620}, title={All Pairs Shortest Distances for Graphs with Small Integer Length Edges}, author={Zvi Galil and Oded Margalit}, pages={103--139}, journal=iandcomp, month={1~} # may, year=1997, volume=134, number=2, abstract={There is a way to transform the All Pairs Shortest Distances (APSD) problem where the edge lengths are integers with small ($\le M$) absolute value into a problem with edge lengths in~$\{-1, 0, 1\}$. This transformation allows us to use the algorithms we developed earlier ([1]) and yields quite efficient algorithms. In this paper we give new improved algorithms for these problems. For $n = |V|$ the number of vertices, $M$~the bound on edge length, and $\omega$~the exponent of matrix multiplication, we get the following results: \begin{enumerate} \item A directed nonnegative $\mathrm{APSD}(n, M)$ algorithm which runs in $O(T(n, M))$ time, where \[ T(n, M) = \begin{cases} M^{(\omega -1 )/2} n^{(3 + \omega)/2}, & 1 \le M \le n^{(3-\omega)/(\omega + 1)}\\ M n^{(5\omega - 3)/(\omega + 1)}, & n^{(3 - \omega)/(\omega + 1)} \le M \le n^{2(3 - \omega)/(\omega + 1)}. \end{cases} \] \item A undirected $\mathrm{APSD}(n, M)$ algorithm which runs in $O(M^{(\omega + 1)/2} n^\omega \log (MN))$ time. \end{enumerate}}, references={focs::AlonGM1991, stoc::CoppersmithW1987, stoc::Seidel1992} } Volume 135, Number 1 May 25, 1997 @Article{KantB1997, refkey={C1341; PN2635}, title={Triangulating Planar Graphs While Minimizing the Maximum Degree}, author={Goos Kant and Hans L. Bodlaender}, pages={1--14}, journal=iandcomp, month={25~} # may, year=1997, volume=135, number=1, abstract={In this paper we consider the problem how to augment a planar graph to a triangulated planar graph while minimizing the maximum degree increase. We show that the general problem is NP-complete for biconnected planar graphs. An approximation algorithm is presented to triangulate triconnected planar graphs such that the maximum degree of the triangulation is at most $d + 8$, where $d$ is the maximum degree of the input graph. Generalizing this result yields a triangulation algorithm for general planar graphs with maximum degree at most an additional constant larger than existing lower bounds.}, references={stoc::BattistaV1993, sicomp::EswaranT1976, focs::Frank1990, focs::Gabow1991, tcs::GareyJS1976, focs::Hsu1992, focs::HsuR1991, focs::Kant1992, jalgo::Kant1996, focs::NaorGM1990, sicomp::RosenthalG1977, soda::Schnyder1990, jcss::WatanabeN1987, jcss::WatanabeN1993} } @Article{SkodinisW1997, refkey={C1744; PN2628}, title={The Bounded Degree Problem for {eNCE} Graph Grammars}, author={Konstantin Skodinis and Egon Wanke}, pages={15--35}, journal=iandcomp, month={25~} # may, year=1997, volume=135, number=1, abstract={The complexity of the bounded degree problem is analyzed for graph languages generated by eNCE graph grammars. In particular, the bounded degree problem is shown to be undecidable for eNCE graph grammars, DEXPTIME-complete for confluent/boundary eNCE graph grammars, PSPACE-complete for linear eNCE graph grammars, and P-complete for non-blocking eNCE graph grammars. In our main theorem we show that the bounded degree problem is NL-complete for reduced non-blocking eNCE graph grammars. Many of the shown results carry over to other type of graph grammars.}, references={jcss::CourcelleER1993, ic::Courcelle1995, ic::EngelfrietL1989, jcss::EngelfrietLW1990, ic::EngelfrietR1990, sicomp::Immerman1987, jcss::JanssensRW1986, actai::Lautemann1989:399, ic::RozenbergW1986, jcss::SkodinisW1995} } @Article{AhlswedeC1997, refkey={C1621; PN2629}, title={Models of Multi-User Write-Efficient Memories and General Diametric Theorems}, author={Rudolf Ahlswede and Ning Cai}, pages={37--67}, journal=iandcomp, month={25~} # may, year=1997, volume=135, number=1, abstract={Write-efficient memories (WEM) were introduced by Ahlswede/Zhang as a model for storing and updating information on a rewritable medium. We strengthen the capacity theorem by providing a full control of the rates of the spreads. Next we address and settle for the storage capacity region problem under the average costs constraint for the case of many users who write on the memory in an arbitrary order, where neither the encoder nor the decoders knows the previous content of the memory. The combinatorial essence is a diametric theorem for several families. Finally we present a storage capacity theorem for several persons using the memory in cyclic order.}, references={ieeetit::AhlswedeK1975, ic::AhlswedeZ1989, ieeetit::AhlswedeZ1994} } Volume 135, Number 2 June 15, 1997 @Article{LeoneRS1997, refkey={C1835; PN2630}, title={Disjunctive Stable Models: Unfounded Sets, Fixpoint Semantics, and Computation}, author={Nicola Leone and Pasquale Rullo and Francesco Scarcello}, pages={69--112}, journal=iandcomp, month={15~} # jun, year=1997, volume=135, number=2, abstract={Disjunctive logic programs have become a powerful tool in knowledge representation and commonsense reasoning. This paper focuses on stable model semantics, currently the most widely acknowledged semantics for disjunctive logic programs. After presenting a new notion of unfounded sets for disjunctive logic programs, we provide two declarative characterizations of stable models in terms of unfounded sets. One shows that the set of stable models coincides with the family of unfounded-free models (i.e., a model is stable iff it contains no unfounded atoms). The other proves that stable models can be defined equivalently by a property of their false literals, as a model is stable iff the set of its false literals coincides with its greatest unfounded set. We then generalize the well-founded~$\mathcal{W}_{\mathcal{P}}$ operator to disjunctive logic programs, give a fixpoint semantics for disjunctive stable models and present an algorithm for computing the stable models of function-free programs. The algorithm's soundness and completeness are proved and some complexity issues are discussed.}, references={jlogp::AptB1994, jlogp::BaralG1994, pods::BellNNS1992, jacm::BellNNS1994, jlogp::BuccafurriLR1996, jacm::DavisP1960, pods::EiterGM1994, acmtds::EiterGM1997, jlogp::FernandezM1995, jlogp::Fitting1993, jlogp::InoueS1996, tcs::MarekS1992, jacm::MarekT1991, jlogp::MinkerR1990, pods::SaccaZ1990, jlogp::SeipelMR1997, tkde::SubrahmanianNV1995, jacm::GelderRS1991, stoc::Vardi1982} } @Article{Tyszkiewicz1997, refkey={C1856; PN2636}, title={The {Kolmogorov} Expression Complexity of Logics}, author={Jerzy Tyszkiewicz}, pages={113--135}, journal=iandcomp, month={15~} # jun, year=1997, volume=135, number=2, abstract={The purpose of the paper is to propose a completely new notion of complexity of logics in finite-model theory. It is the Kolmogorov variant of the Vardi's \emph{expression complexity}. We define it by considering the value of the Kolmogorov complexity $C(L[\mathscr{U}])$ of the infinite string~$L[\mathscr{U}]$ of all truth values of sentences of~$L$ in~$\mathscr{U}$. The higher is this value, the more expressive is the logic~$L$ in~$\mathscr{U}$. If $\mathcal{D}$ is a class of finite models, then the value of $C(L[\mathscr{U}])$ over all $\mathscr{U} \in \mathcal{D}$ is a measure of expressive power of~$L$ in~$\mathcal{D}$. Unboundedness of $C(L[\mathscr{U}]) - C(L'[\mathscr{U}])$ for $\mathscr{U} \in \mathcal{D}$ implies nonexistence of a recursive interpretation of~$L$ in~$L'$. A version of this statement with complexities modulo oracles implies the nonexistence of any interpreation of~$L$ in~$L'$. Thus the values $C(L[\mathscr{U}])$ modulo oracles constitute an invariant of the expressive power of logics over finite models, depending on their real (absolute) expressive power, and not on the syntax. We investigate our notion for fragments of the infinitary logic~$\mathcal{L}^\omega_{\infty \omega}$: least fixed point logic (LFP) and partial fixed point logic (PFP)\@. We prove a precise characterization of 0--1 laws for these logics in terms of a certain boundedness condition placed on~$C(L[\mathscr{U}])$. We get an extension of the notion of a 0--1 law by imposing an upper bound on teh value of $C(L[\mathscr{U}])$ growing not too fast with cardinality of~$\mathscr{U}$, which still implies inexpressibility results similar to those implied by 0--1 laws. We also discuss classes~$\mathcal{D}$ in which $C(\mathrm{PFP}^k[\mathscr{U}])$ is very high. It appears that then PFP or its simple extension can defined all the PSPACE subsets of~$\mathcal{D}$.}, references={jcss::AbiteboulV1991, stoc::AbiteboulV1991, sicomp::BlassG1995, popl::Chandra1981:50, jcss::ChandraH1980, ic::DawarLW1995, jsyml::Fagin1976, tcs::Fagin1993, jsyml::HellaLV1996, ic::Immerman1986, lics::Seth1995, jlogc::Shelah1996, icdt::Tyszkiewicz1995, stoc::Vardi1982} } Volume 136, Number 1 July 10, 1997 @Article{Strauss1997, refkey={C1896; PN2639}, title={Measure on~{P}: Strength of the Notion}, author={Martin Strauss}, pages={1--23}, journal=iandcomp, month={10~} # jul, year=1997, volume=136, number=1, abstract={We give a notion of measure at~P in a paradigm that differs somewhat from the standard theory. Our new notion overcomes some limitations of earlier formulations, specifically, concerning closure of null sets under union. First, we analyze some of the difficulties in defining measure at~P\@. We then present the new definitions and determine the basic properties of the notion, including the density and immunity characteristics of a random language. We argue that these results are parallel to previous measure results at exponential time.}, references={focs::AroraLMSS1992, sicomp::AllenderR1988, mfcs::AllenderS1995, stoc::BabaiFLS1991, tcs::HartmanisY1984, sicomp::Lutz1990, jcss::Lutz1992, focs::ReganSC1995} } @Article{AlbersH1997, refkey={C1846; PN2632}, title={Improved Parallel Integer Sorting without Concurrent Writing}, author={Susanne Albers and Torben Hagerup}, pages={25--51}, journal=iandcomp, month={10~} # jul, year=1997, volume=136, number=1, abstract={We show that $n$ integers in the range $1, \dots, n$ can be sorted stably on an EREW PRAM using $O(t)$ time and $O(n(\sqrt{\,\log n \log \log n} + (\log n)^2/t))$ operations, for arbitrary given $t \ge \log n \log\log n$, and on a CREW PRAM using $O(t)$ time and $O(n(\sqrt{\,\log n} + \log n/2^{t/\log n}))$ operations, for arbitrary given $t \ge \log n$. In addition, we are able to sort $n$ arbitrary integers on a randomized CREW PRAM within the same resource bounds with high probability. In each case our algorithm is a factor of almost $\Theta(\sqrt{\,\log n})$ closer to optimality than all previous algorithms for the stated problem in the stated model, and our third result matches the operation count of the best previous sequential algorithm. We also show that $n$ integers in the range $1, \dots, m$ can be sorted in $O((\log n)^2)$ time with $O(n)$ operations on an EREW PRAM using a nonstandard word length of $O(\log n \log \log n \log m)$ bits, thereby greatly improving the upper bound on the word length necessary to sort integers with a linear time--processor product, even sequentially. Our algorithms were inspired by, and in one case directly use, the fusion trees of Fredman and Willard.}, preliminary={soda::AlbersH1992}, references={stoc::AjtaiKS1983, focs::Andersson1995, stoc::AnderssonHNR1995, ic::BastH1995, ic::BerkmanV1993, ic::BhattDHPRS1991, sicomp::Cole1988, ic::ColeV1986, jcss::FredmanW1993, focs::GilMV1991, soda::GoodrichMV1994, stoc::Hagerup1991, focs::HagerupR1992, spaa::HagerupR1993,ipl::HagerupR1989, ipl::HagerupS1990, tcs::KirkpatrickR1984, algor::KruskalRS1990, tcs::KruskalRS1990, jalgo::MatiasV1991, stoc::MatiasV1991, sicomp::RajasekaranR1989, actai::RajasekaranS1992, soda::thorup1996, ipl::Boas1977} } @Article{KfouryS1997, refkey={C1825; PN2640}, title={An Infinite Pebble Game and Applications}, author={A. J. Kfoury and A. P. Stolboushkin}, pages={53--66}, journal=iandcomp, month={10~} # jul, year=1997, volume=136, number=1, abstract={We generalize the pebble game to infinite directed acyclic graphs and use this generalization to give new and shorter proofs of the following well-known results: (1)~that unbounded memory increases the power of logics of programs, and (2)~that there exists a context-free grammar with infinite index.}, references={stoc::Ben-OrC1988, stoc::KalyanasundaramS1988:258, tcs::Kfoury1983, stoc::Kozen1984, ic::MusikaevT1993, jcss::Pippenger1981, ic::Salomaa1969, ic::Tiuryn1984} } Volume 136, Number 2 August 1, 1997 @Article{LeveneL1997, refkey={C1632; PN2631}, title={Null Inclusion Dependencies in Relational Databases}, author={Mark Levene and George Loizou}, pages={67--108}, journal=iandcomp, month={1~} # aug, year=1997, volume=136, number=2, abstract={Functional dependencies (FDs) and inclusion dependencies (INDs) are the most fundamental integrity constraints that arise in practice in relational databases. We introduce null inclusion dependencies (NINDs) to cater for the situation when a database is incomplete and contains null values. We show that the implication problem for NINDs is the same as that for INDs. We then present a sound and complete axiom system for null functional dependencies (NFDs) and NINDs, and prove that the implication problem for NFDs and NINDs is decidable and EXPTIME-complete. By contrast, when no nulls are allowed, this implication problem is undecidable. This undecidability result has motivated several researchers to restrict their attention to FDs and noncircular INDs in which case the implication problem was shown to be EXPTIME-complete. Our results imply that when considering nulls in relational database design we need not assume that NINDs are noncircular.}, references={ic::AtzeniM1986, jcss::CasanovaFP1984, jacm::ChandraKS1981, sicomp::ChandraV1985, acmtds::Codd1979, stoc::CosmadakisK1985:273, jacm::CosmadakisKV1990, jacm::Honeyman1982, jcss::JohnsonK1984, actai::LeveneL1997:135, jacm::Lien1982, acmtds::MaierMS1979, ic::Mitchell1983} } @Article{GlabbeekV1997, refkey={C1784; PN2634}, title={The Difference between Splitting in~{$n$} and {$n + 1$}}, author={Rob van Glabbeek and Frits Vaandrager}, pages={109--142}, journal=iandcomp, month={1~} # aug, year=1997, volume=136, number=2, abstract={It is established that durational and structural aspects of actions can in general not be modeled in standard interleaving semantics, even when a time-consuming action is represented by a pair of instantaneous actions denoting its start and finish. By means of a series of counterexamples it is shown that, for any~$n$, it makes a difference whether actions are split in~$n$ or $n + 1$ parts.}, references={ic::AcetoH1993, ic::AcetoH1994, ic::GorrieriL1995, sicomp::Hennessy1988, tcs::NielsenPW1981, tcs::Vaandrager1991, tcs::Vogler1993, ic::Vogler1995, ic::Vogler1996} } @Article{VenkatesanRMMR1997, refkey={C1911; PN2641}, title={Restrictions of Minimum Spanner Problems}, author={G. Venkatesan and U. Rotics and M. S. Madanlal and J. A. Makowsky and C. Pandu Rangan}, pages={143--164}, journal=iandcomp, month={1~} # aug, year=1997, volume=136, number=2, abstract={A $t$-spanner of a graph~$G$ is a spanning subgraph~$H$ such that the distance between any two vertices in~$H$ is at most $t$ times their distance in~$G$. Spanners arise in the context of approximating the original graph with a sparse subgraph (Peleg, D., and Sch\"affer, A. A. (1989), \emph{J.~Graph.\ Theory} \textbf{13}~(1), 99--116). The MINIMUM $t$-SPANNER problem seeks to find a $t$-spanner with the minimum number of edges for the given graph. In this paper, we completely settle the complexity status of this problem for various values of~$t$, on chordal graphs, split graphs, bipartite graphs and convex bipartite graphs. Our results settle an open question raised by L.~Cai (1994, \emph{Discrete Appl.\ Math.}~\textbf{48}, 187--194) and also greatly simplify some of the proofs presented by Cai and L.~Cai and M.~Keil (1994, \emph{Networks} \textbf{24}, 233--249). We also give a factor~2 approximation algorithm for the MINIMUM 2-SPANNER problem on interval graphs. Finally, we provide approximation algorithms for the bandwidth minimization problem on convex bipartite graphs and split graphs using the notion of tree spanners.}, references={jacm::Awerbuch1985, jcss::BoothL1976:335, ipl::MandanlalVR1996:97, stoc::PelegU1988, ipl::RamalingamR1988, sicomp::Yannakakis1981} } Volume 137, Number 1 August 25, 1997 @Article{FairtloughM1997, refkey={C1747; PN2627}, title={Propositional Lax Logic}, author={Matt Fairtlough and Michael Mendler}, pages={1--33}, journal=iandcomp, month={25~} # aug, year=1997, volume=137, number=1, abstract={We investigate a peculiar intuitionistic modal logic, called Propositional Lax Logic (PLL), which has promising applications to the formal verification of computer hardware. The logic has emerged from an attempt to express correctness up to behavioural constraints---a central notion in hardware verification---as a logical modality. As a modal logic it is special since it features a single modal operator~$\bigcirc$ that has a flavour both of possibility and of necessity. In the paper we provide the motivation for PLL and present several technical results. We investigate some of its proof-theoretic properties, presenting a cut-elimination theorem for a standard Gentzen-style sequent presentation of the logic. We go on to define a new class of fallible two-frame Kripke models for~PLL\@. These models are unusual since they feature worlds with inconsistent information; furthermore, the only frame condition imposed is that the $\bigcirc$-frame be a subrelation of the $\supset$-frame. We give a natural translation of these models into Goldblatt's $\mathcal{J}$-space models of~PLL\@. Our completeness theorem for these models yields a G\"odel-style embedding of PLL into a classical bimodal theory of type~(S4, S4) and underpins a simple proof of the finite model property. We proceed to prove soundness and completeness of several theories for specialized classes of models. We conclude with a brief exploration of two concrete and rather natural types of model from hardware verification for which the modality~$\bigcirc$ models correctness up to timing constraints. We obtain decidability of $\bigcirc$-free fragment of the logic of the first type of model, which coincides with the stable form of Maksimova's intermediate logic~$L/7$.}, references={jsyml::Curry1952, jsyml::Ewald1986, jsyml::GabbayD1974, ndjfl::MiglioliMOQU1989, ic::Moggi1991} } @Article{Intrigila1997, refkey={C1879; PN2633}, title={Non-Existent {Statman's} Double FixedPoint Combinator Does Not Exist, Indeed}, author={Benedetto Intrigila}, pages={35--40}, journal=iandcomp, month={25~} # aug, year=1997, volume=137, number=1, abstract={We give a negative answer to a problem of R.~Statman concerning the existence, in the lambda calculus, of a fixed point combinator~$Y$ such that $Y(\mathbf{SI}) = Y$ holds.}, references={tcs::Statman1993} } @Article{FalaschiGMP1997, refkey={C1778; PN2638}, title={Constraint Logic Programming with Dynamic Scheduling: A Semantics Based on Closure Operators}, author={Moreno Falaschi and Maurizio Gabbrielli and Kim Marriott and Catuscia Palamidessi}, pages={41--67}, journal=iandcomp, month={25~} # aug, year=1997, volume=137, number=1, abstract={The first logic programming languages, such as Prolog, used a fixed left-to-right atom scheduling rule. Recent logic programming languages, however, provide more flexible schedule scheduling in which some calls are dynamically ``delayed'' until their arguments are sufficiently instantiated to allow the call to run efficiently. Such languages include constraint logic programming languages, since most implementations of these languages delay constraints which are ``too hard.'' From the semantic point of view, the fact that an atom must be delayed under certain conditions, causes the standard semantics of (constraint) logic programming to be no longer adequate to capture the meaning of a program. In our paper we attack this problem and we develop a denotational semantics for constraint logic programming with dynamic scheduling. The key idea is that the denotation of an atom or goal is a set of closure operators, where different closure operators correspond to different sequences of rule choices.}, references={tcs::FalaschiLPM1989:289, jlogc::GabbrielliDL1995, popl::JaffarL1987, popl::MarriottBH1994, popl::SaraswatRP1991, jacm::EmdenK1976, popl::YelickZ1989} } @Article{Lafont1997, refkey={C1789; PN2643}, title={Interaction Combinators}, author={Yves Lafont}, pages={69--101}, journal=iandcomp, month={25~} # aug, year=1997, volume=137, number=1, abstract={It is shown that a very simple system of \emph{interaction combinators}, with only three symbols and six rules, is a universal model of distributed computation, in a sense that will be made precise. This paper is the continuation of the author's work on \emph{interaction nets}, inspired by Girard's proof nets for \emph{linear logic}, but no preliminary knowledge of these topics is required for its reading.}, references={popl::GonthierAL1992, lics::GonthierAL1992, popl::Lafont1990, popl::Lamping1990} } Volume 137, Number 2 September 15, 1997 @Article{CzumajHS1997, refkey={C1867; PN2642}, title={Simulating Shared Memory in Real Time: On the Computation Power of Reconfigurable Architectures}, author={Artur Czumaj and Meyer auf der Heide, Friedhelm and Volker Stemann}, pages={103--120}, journal=iandcomp, month={15~} # sep, year=1997, volume=137, number=2, abstract={We consider randomized simulations of shared memory on a distributed memory machine (DMM) where the $n$ processors and the $n$ memory modules of the DMM are connected via a reconfigurable architecture. We first present a randomized simulation of a CRCW PRAM on a reconfigurable DMM having a complete reconfigurable DMM having a complete reconfigurable interconnection. It guarantees delay $\mathcal{O}(\log^* n)$, with high probability. Next we study a reconfigurable mesh DMM (RM-DMM)\@. Here the $n$ processors and $n$ modules are connected via an $n \times n$ reconfigurable mesh. It was already known that an $n \times m$ reconfigurable mesh can simulate in constant time an $n$-processor CRCW PRAM with shared memory of size~$m$. In this paper we present a randomized step simulation of a CRCW PRAM with arbitrarily large shared memory on an RM-DMM\@. It guarantees constant delay with high probability, i.e., it simulates in real time. Finally we prove a lower bound showing that size~$\Omega(n^2)$ for the reconfigurable mesh is necessary for real time simulations.}, references={ic::Ben-AsherLPS1995, sicomp::BerkmanV1993, jcss::CarterW1979, sicomp::DietzfelbingerKMHRT1994, spaa::DietzfelbingerH1993, spaa::GoldbergMR1994, stoc::KarlinU1986, algor::KarpLH1996, stoc::KarpLH1992, stoc::Leighton1992, stoc::MacKenziePR1994, tcs::HeideSS1996, jalgo::Ragde1993, jcss::Ranade1991, focs::Siegel1989, jacm::Upfal1984, jacm::UpfalW1987, ipl::WangC1990:31} } @Article{AcetoF1997, refkey={C1908; PN2645}, title={An Equational Axiomatization for Multi-exit Iteration}, author={Luca Aceto and Wan Fokkink}, pages={121--158}, journal=iandcomp, month={15~} # sep, year=1997, volume=137, number=2, abstract={This paper presents an equational axiomatization of bisimulation equivalence over the language of Basic Process Algebra (BPA) with multi-exit iteration. Multi-exit iteration is a generalization of the standard binary Kleene star operation that allows for the specification of agents that, up to bisimulation equivalence, are solutions of systems of recursion equations of the form \begin{align*} X_1 & \stackrel{\mathrm{def}}{=} P_1 X_2 + Q_1 \\ & \vdots \\ X_n & \stackrel{\mathrm{def}}{=} P_n X_1 + Q_n \end{align*} where $n$ is a positive integer and the $P_i$ and the~$Q_i$ are process terms. The addition of multi-exit iteration to BPA yields a more expressive language than that obtained by augmenting BPA with the standard binary Kleene star (BPA*). As a consequence, the proof of completeness of the proposed equational axiomatization for this language, although standard in its general structure, is much more involved than that for BPA*. An expressiveness hierarchy for the family of $k$-exit iteration operators proposed by Bergstra, Bethke, and Ponse is also offered.}, references={ic::AcetoGFI1996:26, jacm::BaetenBK1993, tcs::BergstraK1985, mscs::BloomE1993, jacm::CopiEW1958, ic::FokkinkG1996, ipl::Fokkink1994, ic::Kozen1994, tcs::Krob1991, jcss::Milner1984, ic::Milner1989, jacm::Salomaa1966, lics::Sewell1994, mscs::Troeger1993} } @Article{CookIY1997, refkey={C1871; PN2646}, title={A Tight Relationship between Generic Oracles and Type-2 Complexity Theory}, author={Stephen Cook and Russell Impagliazzo and Tomoyuki Yamakami}, pages={159--170}, journal=iandcomp, month={15~} # sep, year=1997, volume=137, number=2, abstract={We show that any two complexity classes satisfying some general conditions are distinct relative to a generic oracle iff the corresponding type-2 classes are distinct.}, references={sicomp::BakerGS1975, stoc::BeameCEIP1995, focs::BlumI1987, stoc::Constable1973, stoc::Cook1971, apal::CookU1993, sctc::FennerFKL1993, ipl::FortnowS1988, jcss::FortnowY1996, mst::FurstSS1984, jsyml::Harnik1992, sctc::HartmanisH1987, tcs::HartmanisH1990, sctc::ImpagliazzoN1988, jsymc::KaltofenT1990, sicomp::KapronC1996, tcs::Ko1985, jacm::LundFKN1992, jcss::Mehlhorn1976, focs::Papadimitriou1990, jsyml::Poizat1986, jacm::Rackoff1982, jacm::Shamir1992:869, stoc::sipser1983:61, ndjfl::Townsend1990, ic::Yamakami1995, mst::Yamakami1992, focs::Yao1985} } Volume 138, Number 1 October 10, 1997 @Article{ChaudhuriR1997, refkey={C1546; PN2654}, title={The Complexity of Parallel Prefix Problems on Small Domains}, author={Shiva P. Chaudhuri and Jaikumar Radhakrishnan}, pages={1--22}, journal=iandcomp, month={10~} # oct, year=1997, volume=138, number=1, abstract={We establish non-trivial lower bounds for several prefix problems in the CRCW PRAM model. The chaining problem is, given a binary input, for each~1 in the input, to find the index of the nearest~1 to its left. Our main result is that for an input of $n$~bits, solving the chaining problem using $O(n)$ processors requires inverse-Ackerman time. This matches the previously known upper bound. We also give a reduction to show that the same lower bound applies to a parenthesis matching problem, again matching the previously known upper bound. We also give reductions to show that similar bounds hold for the prefix maxima and the range maxima problem.}, references={stoc::Boppana1989:320, stoc::BerkmanBGSV1989:309, ic::BhattDHPRS1991:29, jacm::BeameH1989:643, focs::BerkmanJKTV1990:871, sicomp::BerkmanV1993:221, jcss::ChandraFL1985:222, sicomp::Chaudhuri1994:1253, focs::ChaudhuriR1992:638, ic::Chaudhuri1993:132, stoc::DolevDPW1983:42, algor::FichRW1988:43, focs::GilMV1991:698, soda::MacKenzie1992:94, jalgo::MatiasV1991:573, sicomp::HeideW1987:100, jalgo::Ragde1993:371, sicomp::Snir1985:688} } @Article{FreundKRRSS1997, refkey={C1915; PN2648}, title={Efficient Learning of Typical Finite Automata from Random Walks}, author={Yoav Freund and Michael Kearns and Dana Ron and Ronitt Rubinfeld and Robert E. Schapire and Linda Sellie}, pages={23--48}, journal=iandcomp, month={10~} # oct, year=1997, volume=138, number=1, abstract={This paper describes new and efficient algorithms for learning deterministic finite automata. Our approach is primarily distinguished by two features: (1)~the adoption of an average-case setting to model the ``typical'' labeling of a finite automaton, while retaining a worst-case model for the underlying graph of the automaton, along with (2)~a learning model in which the learner is not provided with the means to experiment with the machine, but rather must learn solely by observing the automaton's output behavior on a random input sequence. The main contribution of this paper is in presenting the first efficient algorithms for learning nontrivial classes of automata in an entirely passive learning model. We adopt an on-line learning model in which the learner is asked to predict the output of the next state, given the next symbol of the random input sequence; the goal of the learner is to make as few prediction mistakes as possible. Assuming the learner has a means of resetting the target machine to a fixed start state, we first present an efficient algorithm that makes an expected polynomial number of mistakes in this model. Next, we show how this first algorithm can be used as a subroutine by a second algorithm that also makes a polynomial number of mistakes even in the absence of a reset. Along the way, we prove a number of combinatorial results for randomly labeled automata. We also show that the labeling of the states and the bits of the input sequence need not be truly random, but merely \emph{semi-random}. Finally, we discuss an extension of our results to a model in which automata are used to represent distributions over binary strings.}, references={ic::Angluin1978, ic::Angluin1987, stoc::AzarBKLP1992, jacm::blum1994, sicomp::ChorG1988, ieeetit::FederMG1992, ic::Gold1978, ic::HausslerLW1994, stoc::KearnsMRRSS1994, jacm::KearnsV1994, jacm::PittW1993, jacm::PittV1988, jcss::PittW1990, jacm::RivestS1994, ic::RivestS1993, jcss::SanthaV1986, focs::VaziraniV1985} } @Article{Rabinovich1997:49, refkey={C1839; PN2658}, title={On Schematological Equivalence of Partially Interpreted Dataflow Networks}, author={Alexander Rabinovich}, pages={49--87}, journal=iandcomp, month={10~} # oct, year=1997, volume=138, number=1, abstract={We provide a schematologically complete set of transformations for partially interpreted dataflow nets. This paper extends our results in (\emph{Inform.\ and Comput.}\ \textbf{124}~(1996), 154--167), where a schematologically complete set of transformations was provided for the nets which consist only of uninterpreted nodes and the results for partially interpreted nets were announced without proofs.}, references={lics::GaifmanP1987:72, popl::Jonsson1989:155, ic::LynchS1989:81, ic::Rabinovich1996:154, lics::Stark1992:125} } @Article{BeameFS1997, refkey={C1507; PN2649}, title={Separating the Power of {EREW} and {CREW PRAMs} with Small Communication Width}, author={Paul Beame and Faith E. Fich and Rakesh K. Sinha}, pages={89--99}, journal=iandcomp, month={10~} # oct, year=1997, volume=138, number=1, abstract={We prove that evaluating a Boolean decision tree of height~$h$ requires $\Omega(h/(m + \log^* h))$ time on any EREW PRAM with communication width~$m$ and any number of processors. Since this function can be easily computed in time $O(\sqrt{h})$ on a CREW PRAM with communication width~1 using $2^{O(h)}$ processors, this gives a separation between the two models whenever the EREW PRAM has communication width~$m \in o(\sqrt{h})$.}, references={sicomp::CookDR1986, spaa::DietzfelbingerKR1990, sicomp::FichW1990, tcs::GafniNR1989, sicomp::Kutylowski1991, sicomp::Nisan1991, sicomp::Snir1985, sicomp::VishkinW1985} } Volume 138, Number 2 November 1, 1997 @Article{Kuper1997, refkey={C1795; PN2655}, title={On the {Jacopini} technique}, author={Jan Kuper}, pages={101--123}, journal=iandcomp, month={1~} # nov, year=1997, volume=138, number=2, abstract={The general concern of the Jacopini technique is the question: ``Is it consistent to extend a given lambda calculus with a certain equations?'' The technique was introduced by Jacopini in 1975 in his proof that in the untyped lambda calculus $\Omega$ is easy, i.e., $\Omega$ can be assumed equal to any other (closed) term without violating the consistency of the lambda calculus. The presentations of the Jacopini technique that are known from the literature are difficult to understand and hard to generalise. In this paper we generalise the Jacopini technique for arbitrary lambda calculi. We introduce the concept of \emph{proof-replaceability} by which the structure of the technique is simplified considerably. We illustrate the simplicity and generality of our formulation of the technique with some examples. We apply the Jacopini technique to the \mbox{\boldmath $\lambda\mu$}-calculus, and we prove a general theorem concerning the consistency of extensions of the \mbox{\boldmath $\lambda\mu$}-calculus of a certain form. Many well known examples (e.g., the easiness of $\Omega$) are immediate consequences of this general theorem.}, references={tcs::BerarducciI1993, tcs::Plotkin1977, ndjfl::Statman1986} } @Article{Bremond-GregoireCL1997, refkey={C1830; PN2657}, title={A Complete Axiomatization of Finite-state {ACSR} Processes}, author={Patrice Br{\'e}mond-Gr{\'e}goire and Jin-Young Choi and Insup Lee}, pages={124--159}, journal=iandcomp, month={1~} # nov, year=1997, volume=138, number=2, abstract={A real-time process algebra, called ACSR, has been developed to facilitate the specification and analysis of real-time systems. ACSR supports synchronous timed actions and asynchronous instantaneous events. Timed actions are used to represent the usage of resources and to model the passage of time. Events are used to capture synchronization between processes. To be able to specify real-time systems accurately, ACSR supports a notion of priority that can be used to arbitrate among timed actions competing for the use of resources and among events that are ready for synchronization. In addition to operators common to process algebra, ACSR includes the scope operator, which can be used to model timeouts and interrupts. Equivalence between ACSR terms is based on the notion of strong bisimulation. This paper briefly describes the syntax and semantics of ACSR and then presents a set of algebraic laws that can be used to prove equivalence of ACSR processes. The contribution of this paper is the soundness and completeness proofs of this set of laws. The completeness proof is for finite-state ACSR processes, which are defined to be processes without free variables under parallel operator or scope operator.}, references={facs::BaetenB1991, tcs::BergstraK1985:77, ic::CleavelandH1990, lics::CamilleriW1991, tcs::DaviesS1995, ic::GerberL1994, tcs::Milner1983, jcss::Milner1984, ic::Milner1989, ic::NicollinS1994, concur::BaetenB1992, concur::Klusener1991, concur::MollerT1990, icalp::Yi1991} } @Article{LatteuxS1997, refkey={C1960; PN2659}, title={Context-Sensitive String Languages and Recognizable Picture Languages}, author={M. Latteux and D. Simplot}, pages={160--169}, journal=iandcomp, month={1~} # nov, year=1997, volume=138, number=2, abstract={The theorem stating that the family of frontiers of recognizable tree languages is exactly the family of context-free languages (see J.~Mezei and J.~B. Wright, 1967, \emph{Inform.\ and Comput.}~\textbf{11}, 3--29), is a basic result in the theory of formal languages. In this article, we prove a similar result: the family of frontiers of recognizable picture languages is exactly the family of context-sensitive languages.}, references={focs::BlumH1967, ic::GiammarresiRST1996, tcs::LatteuxS1997, ic::MezeiW1967, ic::SiromoneySK1973} } @Article{BarveL1997, refkey={C1929; PN2656}, title={On the Complexity of Learning from Drifting Distributions}, author={Rakesh D. Barve and Philip M. Long}, pages={170--193}, journal=iandcomp, month={1~} # nov, year=1997, volume=138, number=2, abstract={We consider two models of on-line learning of binary-valued functions from drifting distributions due to~Bartlett. We show that if each example is drawn from a joint distribution which changes in total variation distance by at most $O(\epsilon^3/(d \log (1/\epsilon)))$ between trials, then an algorithm can achieve a probability of a mistake at most $\epsilon$ worse than the best function in a class of VC-dimension~$d$. We prove a corresponding necessary condition of~$O(\epsilon^3/d)$. Finally, in the case that a fixed function is to be learned from noise-free examples, we show that if the distributions on the domain generating the examples change by at most $O(\epsilon^2/(d \log (1/\epsilon)))$, then any consistent algorithm learns to within accuracy~$\epsilon$.}, references={focs::AroraBSS1993, focs::AuerW1995, jacm::BlumerEHW1989, ic::EhrenfeuchtHKV1989, ic::Haussler1992, ic::HausslerLW1994, ic::LittlestoneW1994, cacm::Valiant1984, colt::Simon1993:402} } @Article{Segala1997, refkey={C1792; PN2652}, title={Quiescence, Fairness, Testing, and the Notion of Implementation}, author={Roberto Segala}, pages={194--210}, journal=iandcomp, month={1~} # nov, year=1997, volume=138, number=2, preliminary={concur::Segala1993}, abstract={Two formalisms for concurrency, the Input/Output automaton model and the theory of testing, are compared and are shown to have common foundations. The relationship between the fair and quiescent preorders of I/O automata is investigated and the two preorders are shown to coincide subject to some restrictions. I/O automata are encoded into the theory of testing and the reversed \textsc{must} preorder is shown to be equivalent to the quiescent preorder for strongly convergent, finitely branching I/O automata up to encoding. Conversely, a theory of testing is defined directly on I/O automata, and the new reversed \textsc{must} preorder is shown to coincide with the quiescent preorder on strongly convergent, finitely branching I/O automata.}, references={ipl::AlpernS1985:181, jacm::BrookesHR1984:560, actai::Nicola1987:211, tcs::NicolaH1984:83, actai::Josephs1992:17, facs::LynchS1995:231, podc::LynchT1987:137, lics::Vaandrager1991:387} } Volume 139, Number 1 November 25, 1997 @Article{AumannBZ1997, refkey={C1963; PN2653}, title={Efficient Execution of Nondeterministic Parallel Programs on Asynchronous Systems}, author={Yonatan Aumann and Michael A. Bender and Lisa Zhang}, pages={1--16}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={We consider the problem of asynchronous execution of parallel programs. We assume that the original program is designed for a synchronous system, whereas the actual system may be asynchronous. We seek an \emph{automatic execution scheme}, which allows the asynchronous system to execute the synchronous program. Previous execution schemes provide solutions only for the case where the original program is deterministic. Here, we provide the first solution for the more general case where the original program can be nondeterministic (e.g., randomized). Our scheme is based on a novel agreement protocol for the asynchronous parallel setting. Our protocol allows $n$ asynchronous processors to agree on $n$~\emph{word-sized} values in $O(n \log n \log \log n)$ \emph{total work}, assuming an oblivious adversary scheduler. Total work is defined to be the summation of the number of steps performed by all processors (including steps from busy waiting).}, preliminary={spaa::AumannBZ1996}, references={jalgo::AspnesH1990:441, focs::AspnesW1992:137, focs::AumannKPR1993:271, focs::AumannR1992:147, tcs::AumannR1994:3, spaa::ColeZ1989:169, jacm::DolevDS1987:77, jacm::FischerLP1985:374, stoc::FortuneW1978:114, spaa::Gibbons1989:158, stoc::KedemPRR1992:306, stoc::KedemPRS1991:381, stoc::KedemPS1990:138, focs::MartelSP1990:590, spaa::Nishimura1990:76, cacm::Valiant1990:103, podc::Abrahamson1988, podc::Aspnes1990, podc::AttiyaDS1989, icalp::AumannB1996, wdag::BrachaR1991, podc::Chandra1996, podc::ChorIL1987, podc::KanellakisS1989, podc::KanellakisS1991} } @Article{Frougny1997, refkey={C1902; PN2650}, title={On the Sequentiality of the Successor Function}, author={Christiane Frougny}, pages={17--38}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={Let $U$ be a strictly increasing sequence of integers. By a greedy algorithm, every nonnegative integer has a greedy $U$-representation. The successor function maps the greedy $U$-representation of~$N$ onto the greedy $U$-representation of~$N + 1$. We characterize the sequences~$U$ such that the successor function associated with~$U$ is a left, resp.\ a right, sequential function. We also show that the odometer associated to~$U$ is continuous if and only if the successor function is right sequential.}, references={tcs::Choffrut1977, stacs::Frougny1996, tcs::FrougnyS1998, icalp::Shallit1992} } @Article{Ghelli1997, refkey={C1772; PN2662}, title={Termination of System {$F$}-bounded: A Complete Proof}, author={Giorgio Ghelli}, pages={39--56}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={System $F$-bounded is a second-order types $\lambda$-calculus with subtyping which has been defined to carry out foundational studies about the type systems of object-oriented languages. The almost recursive nature of the essential feature of this system makes one wonder whether it retains the strong normalization property, with respect to first- and second-order $\beta\eta$ reduction of system~$F_\le$. We prove that this is the case. The proof is carred out to the last detail to allow the reader to be convinced of its correctness.}, references={toplas::AmadioC1993, jfp::Bruce1994, ic::BruceL1990, ic::CardelliMMS1994, acmcs::CardelliW1985, mscs::CurienG1992, ic::CurienG1994, tacs::FisherM1994, popl::KatiyarLM1994, ic::McAllesterKO1995, popl::Mitchell1990, jfp::PierceT1994, jsyml::Tait1967, ecoop::AbadiC1995, tapos::BruceCCESTLP1995:221, ecoop::BruceSG1995, fpca::CanningCHMO1989, oopsla::EifrigSTZ1994} } @Article{BarbaneraB1997, refkey={C1679; PN2663}, title={The Simply-Typed Theory of {$\beta$}-conversion Has No Maximum Extension}, author={Franco Barbanera and Stefano Berardi}, pages={57--61}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={It is proved that no maximum consistent extension exists for the simply typed theory of $\beta$-conversion.}, references={jsyml::Statman1982} } @Article{BloomE1997, refkey={C1818; PN2665}, title={Axiomatizing Shuffle and Concatenation in Languages}, author={Stephen L. Bloom and Zolt{\'a}n {\'E}sik}, pages={62--91}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={We consider the variety~$\mathbf{Lang}$ generated by all language structures $(P_\Sigma, \cdot, \otimes, +, 0, 1)$, and the variety~$\mathbf{Lg}_\le$ of ordered algebras generated by the structures $(P_\Sigma, \cdot, \otimes, 0, 1, \subseteq)$, where $P_\Sigma$ is the powerset of~$\Sigma^*$, and where $B \cdot C$ is the complex concatenation of the languages $B, C \subset \Sigma^*$, \ $B \otimes C$ is their shuffle product, and $B + C$ is their union. We prove that for each finite set~$E$ of equations valid in~$\mathbf{Lang}$ there is a (finite) model~$S_E$ of~$E$ in which some inequation valid in~$\mathbf{Lg}_\le$ fails. It follows that neither variety is finitely axiomatizable.}, references={mscs::BloomE1993, tcs::BloomE1996, jcss::Bloom1976, icalp::EsikB1995, tcs::Gischer1988, mscs::Tschantz1994, sicomp::ValdesTL1982:298, dc::Vogler1991:139} } @Article{BodlaenderLTT1997, refkey={C1990; PN2669}, title={On Interval Routing Schemes and Treewidth}, author={Hans L. Bodlaender and Jan van Leeuwen and Richard Tan and Dimitrios Thilikos}, pages={92--109}, journal=iandcomp, month={25~} # nov, year=1997, volume=139, number=1, abstract={In this paper, we investigate which processor networks allow $k$-label Interval Routing Schemes, under the assumption that costs of edges may vary. We show that for each fixed $k \ge 1$, the class of graphs allowing such routing schemes is closed under minor-taking in the domain of connected graphs, and hence has a linear time recognition algorithm. This result connects the theory of compact routing with the theory of graph minors and treewidth. We show that every graph that does not contain~$K_{2,r}$ as a minor has treewidth at most~$2r - 2$. As a consequence, graphs that allow $k$-label Interval Routing Schemes under dynamic cost edges have treewidth at most~$4k$. Similar results are shown for other types of Interval Routing Schemes.}, references={jalgo::ArnborgLS1991, sicomp::Bodlaender1996, jalgo::Bodlaender1993, algor::BoriePT1992, ic::Courcelle1990, jacm::FellowsL1988, jcss::FellowsL1994, algor::FredericksonJ1988, jalgo::RobertsonS1986} } Volume 139, Number 2 December 15, 1997 @Article{Rabinovich1997:111, refkey={C1755; PN2661}, title={Complexity of Equivalence Problems for Concurrent Systems of Finite Agents}, author={Alexander Rabinovich}, pages={111--129}, journal=iandcomp, month={15~} # dec, year=1997, volume=139, number=2, abstract={A concurrent system of synchronous communicating agents is assembled from simpler sequential agents by parallel composition and hiding. For example, \emph{hide $a_1$, \dots, $a_l$ in $(p_1 \parallel p_2 \,\cdots \parallel p_n)$} describes the system of communicating agents $p_1$, \dots, $p_n$ in which the communication events $a_1$, \dots, $a_l$ are hidden. Consider descriptions of two systems $p$ and~$q$ of synchronously communicating finite state agents. Assume that one wants to check whether $p \sim q$ for one of the commonly used equivalence~$\sim$. We show that this question is PSPACE hard for all equivalences that lie between strong bisimulation and trace equivalences. For some equivalences exponential lower and upper bounds are proven. We also show that this problem is NP hard and co-NP hard even for a class of very simple finite agents.}, references={jacm::BrookesHR1984:560, icalp::Furer1980:234, ic::MayerS1994:293, focs::MeyerS1972:125, sicomp::PaigeT1987:973, stoc::StockmeyerM1973:1, concur::Glabbeek1993, icalp::GrooteV1990, icalp::Rabinovich1992} } @Article{Bozapalidis1997, refkey={C1971; PN2667}, title={Positive Tree Representations and Applications to Tree Automata}, author={Symeon Bozapalidis}, pages={130--153}, journal=iandcomp, month={15~} # dec, year=1997, volume=139, number=2, abstract={A effective classification of tree automata costed over the semirings $\mathbb{R}_+$ and~$\mathbb{N}$ (and more generally of positive tree representations (PTR)) is achieved by means of a global behavior theory. Reducibility and minimality of PTRs is also investigated.}, references={tcs::BerstelR1982, actai::Bozapalidis1991} } @Article{AriolaK1997, refkey={C1880; PN2651}, title={Lambda Calculus with Explicit Recursion}, author={Zena M. Ariola and Jan Willem Klop}, preliminary={LICS::AriolaK1994}, pages={154--233}, journal=iandcomp, month={15~} # dec, year=1997, volume=139, number=2, abstract={This paper is concerned with the study of $\lambda$-calculus with explicit recursion, namely of cyclic $\lambda$-graphs. The starting point is to treat a $\lambda$-graph as a system of recursion equations involving $\lambda$-terms and to manipulate such systems in an unrestricted manner, using equational logic, just as is possible for first-order term rewriting. Surprisingly, now the confluence property breaks down in an essential way. Confluence can be restored by introducing a restraining mechanism on the substitution operation. This leads to a family of $\lambda$-graph calculi, which can be seen as an extension of the family of $\lambda\sigma$-calculi ($\lambda$-calculi with explicit substitution). While the $\lambda\sigma$-calculi treat the let-construct as a first-class citizen, our calculi support the letrec, a feature that is essential to reason about time and space behavior of functional languages and also about compilation and optimizations of programs.}, references={tcs::AriolaA1995, jfp::AbadiCCL1991, jfp::AriolaF1997, popl::AriolaFMOW1995, tacs::AriolakKSV1994:543, mscs::AspertiL1994, jacm::BurstallD1977, toplas::FarmerRW1990:123, popl::Field1990, popl::gonthierAL1992, popl::HendersonM1976, tcs::Kennaway1987, toplas::KennawayKSV1994, ic::KennawayKSV1995, tcs::KlopOR1993, popl::Lafont1990, popl::Lamping1990, popl::Launchbury1993, popl::Lescanne1994, tcs::Lowe1993, toplas::PinterP1994, tcs::Raoult1984, spe::Turner1979, tcs::Wadler1990} } @Article{HinrichsW1997, refkey={C1994; PN2666}, title={Time Bounded Frequency Computations}, author={Maren Hinrichs and Gerd Wechsung}, pages={234--257}, journal=iandcomp, month={15~} # dec, year=1997, volume=139, number=2, abstract={(1)~We obtain two new results concerning the inclusion problem of polynomial time frequency classes with equal numbers of errors. \begin{enumerate} \item $(m, m + d) \mathrm{P} \supsetneq (m + 1, m + d + 1) \mathrm{P}$ for $m < 2^d$. \item $(m, m + d) \mathrm{P} = (m + 1, m + d + 1) \mathrm{P}$ for $m \ge c(d)$ where $c(d)$ is large enough. \end{enumerate} This disproves a conjecture of Kinber. (2)~We give a transparent proof of a generalization of Kinber's result that there exist arbitrarily complex problems admitting a polynomial time frequency computation. Several corollaries provide more insight into the structure of the hierarchy of polynomial time frequency classes. (3)~The relationships between polynomial time frequency classes and selectivity classes are studied.}, references={sctc::AmirBG1990, ic::AmirG1988, ic::BeigelKS1995, stacs::HoeneN1993, jcss::Ko1983, jacm::Ladner1975, stacs::Nickelsen1997, sctc::Ogihara1994, mst::Selman1979} } @Article{AgostinoS1997, refkey={C1953; PN2668}, title={A Worst-Case Analysis of the {LZ2} Compression Algorithm}, author={Sergio De Agostino and Riccardo Silvestri}, pages={258--268}, journal=iandcomp, month={15~} # dec, year=1997, volume=139, number=2, abstract={Sheinwald, Lempel, and Zvi (1995, \emph{Inform.\ and Comput.}\ \textbf{116}, 128--133) proved that the power of off-line coding is not useful if we want on-line decodable files, as far as asymptotical results are concerned. In this paper, we are concerned with the finite case and consider the notion of on-line decodable optimal parsing based on the parsing defined by the Ziv-Lempel (LZ2) compression algorithm. De~Agostino and Storer (1996, \emph{Inform.\ Process.\ Lett.}\ \textbf{59}, 169--174) proved the NP-completeness of computing the optimal parsing and that a sublogarithmic factor approximation algorithm cannot be realized on-line. We show that the Ziv-Lempel algorithm and two widely used practical implementations produce an $\mathrm{O}(n^{1/4})$ approximation of the optimal parsing, where $n$~is the length of the string. By working with de~Bruijn sequences, we show also infinite families of binary strings on which the approximation factor is~$\Theta(n^{1/4})$.}, references={ipl::AgostinoS1996, ieeetit::LempelZ1976, ieeetit::ZivL1977, ic::SheinwaldLZ1995, ieeetit::ZivL1978} } Volume 140, Number 1 January 10, 1998 @Article{Leivant1998:1, title={Preface}, author={Daniel Leivant}, pages={1}, journal=iandcomp, month={10~} # jan, year=1998, volume=140, number=1, note={Special Issue from the workshop on Logic and Computational Complexity (LCC), Indiana University, October 1994} } @Article{CenzerR1998, refkey={C2055; PN2676}, title={Complexity and Categoricity}, author={Douglas Cenzer and Jeffrey B. Remmel}, pages={2--25}, journal=iandcomp, month={10~} # jan, year=1998, volume=140, number=1, abstract={We define a notion of a feasible Scott family of formulas for a feasible model and give various conditions on a Scott family which imply that two models with the same family are feasibly isomorphic. For example, if $A$ and~$B$ possess a common strongly p-time Scott family and both have universe~$\{1\}^*$, then they are p-time isomorphic. These results are applied to the study of permutation structures, linear orderings, equivalence relations, and Abelian groups. For example, conditions on two permutation structures $(A, f)$ and $(B, g)$ are given which imply that $(A, f)$ and $(B, g)$ are p-time isomorphic.}, references={apal::CenzerR1991, apal::CenzerR1992, apal::CenzerR1998, jsyml::Grigorieff1990, sctc::NerodeR1987, apal::NerodeR1989} } @Article{GradelG1998, refkey={C2054; PN2675}, title={Metafinite Model Theory}, author={Erich Gr{\"a}del and Yuri Gurevich}, pages={26--81}, journal=iandcomp, month={10~} # jan, year=1998, volume=140, number=1, abstract={Motivated by computer science challenges, we suggest to extend the approach and methods of finite model theory beyond finite structures. We study definability issues and their relation to complexity on \emph{metafinite structures} which typically consist of (i)~a primary part, which is a finite structure, (ii)~a secondary part, which is a (usually infinite) structure that can be viewed as a structured domain of numerical objects, and (iii)~a set of ``weight'' functions from the first part into the second. We discuss model-theoretic properties of metafinite structures, present results on descriptive complexity, and sketch some potential applications.}, references={stoc::AbiteboulV1991, focs::AdlemanM1975, focs::AdlemanM1976, focs::AroraLMSS1992, jsyml::Barwise1977, pods::BenediktDLW1996, focs::CaiFI1989, jcss::ChandraH1980, apal::ComptonHS1987, pods::Rougemont1995, tcs::Fagin1993, stoc::GradelM1995, pods::GrumbachS1994, apal::GurevichS1986, pods::HirstH1993, jcss::HirstH1996:522, lics::HirstH1996, jcss::HodgsonK1983, jcss::Immerman1982, ic::Immerman1986, sctc::Immerman1987, jsyml::JonesM1984, jcss::KabanzaSW1995:3, pods::KanellakisKR1990, tcs::KentH1982, lics::Otto1994, jsyml::Otto1996, jcss::PapadimitriouY1991, jsyml::Poizat1982, pods::StolboushkinT1996, sicomp::Valiant1979, stoc::Vardi1982} } @Article{KrajicekP1998, refkey={C2053; PN2674}, title={Some Consequences of Cryptographical Conjectures for~{$S^1_2$} and~{EF}}, author={Jan Kraj{\'\i}{\v{c}}ek and Pavel Pudl{\'a}k}, pages={82--94}, journal=iandcomp, month={10~} # jan, year=1998, volume=140, number=1, abstract={We show that there is a pair of disjoint $\mathcal{NP}$-sets, whose disjointness is provable in~$S^1_2$ and which cannot be separated by a set in~$\mathcal{P}/\mathrm{poly}$, if the cryptosystem RSA is secure. Further we show that factoring and the discrete logarithm are implicitly definable in any extension of~$S^1_2$ admitting an $\mathcal{NP}$-definition of primes about which it can prove that no number satisfying the definition is composite. \par As a corollary we obtain that the Extended Frege (EF) proof system does not admit a feasible interpolation theorem unless the RSA cryptosystem is not secure and that an extension of~EF by tautologies~$\tau_p$ ($p$ primes), formalizing that $p$ is not composite, as additional axioms do not admit a feasible interpolation theorem unless factoring and the discrete logarithm are in~$\mathcal{P}/\mathrm{poly}$.}, references={sicomp::AlexiCGS1988, stoc::CleggEI1996, stoc::Cook1975, jsyml::CookR1979, jsyml::Krajicek1994, jsyml::Krajicek1997, jsyml::KrajicekP1989, apal::KrajicekPT1991, apal::Mundici1984, jsyml::ParisWW1988, sicomp::Pratt1975, jsyml::Pudlak1997} } Volume 140, Number 2 February 1, 1998 @Article{Dam1998, refkey={C1857; PN2680}, title={Proving Properties of Dynamic Process Networks}, author={Mads Dam}, pages={95--114}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, preliminary={concur::Dam1995}, abstract={We present the first compositional proof system for checking processes against formulas in the modal $\mu$-calculus which is capable of handling dynamic process networks. The proof system is obtained in a systematic way from an operational semantics of the underlying process algebra. A non-trivial proof example is given, and the proof system is shown to be sound in general, and complete for finite-state processes.}, references={toplas::AbadiL1993, lics::AndersenSW1994, stoc::BarringerKP1984, tcs::BradfieldS1992, actai::Cleaveland1989, tcs::Dam1994, lics::EmersonL1986, actai::Esparza1997, toplas::GrumbergL1994, toplas::Jonsson1994, tcs::Kozen1983, jlogc::LarsenX1991, lics::Simpson1995, tcs::Stirling1988, tcs::StirlingW1991, ic::StreettE1989, tcs::Winskel1991} } @Article{Meyden1998, refkey={C1625; PN2679}, title={Common Knowledge and Update in Finite Environments}, author={Ron van der Meyden}, pages={115--157}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={Logics of knowledge have been show to provide a useful approach to the high level specification and analysis of distributed systems. It has been proposed that such systems can be developed using knowledge-based protocols, in which agents' actions have preconditions that test their state of knowledge. Both computer-assisted analysis of the knowledge properties of systems and automated compilation of knowledge-based protocols require the development of algorithms for the computation of states of knowledge. This paper studies one of the computational problems of interest, the model checking problem for knowledge formulae in the $\mathrm{S}5_n$ Kripke structures generated by finite state environments in which states determine an observation for each agent. Agents are assumed to have perfect recall and may operate synchronously or asynchronously. It is shown that, in this setting, model checking of common knowledge formulae is intractable, but efficient incremental algorithms are developed for formulae containing only knowledge operators. Connections to knowledge updates and compilation of knowledge-based protocols are discussed.}, references={sicomp::Bennett1989, lics::BurchCMDH1990, focs::ChandraS1976, jacm::ChandraKS1981, jcss::chlebus1986, ic::DworkM1990, jacm::FaginHV1991, sicomp::Gradel1990, pods::Hadzilacos1987, jacm::HalpernM1990, stoc::HalpernV1986, jcss::HalpernV1989, jacm::HalpernZ1992, lics::Meyden1994, algor::MosesT1988, focs::PetersonR1979, popl::ReifP1980, jcss::Reif1984} } @Article{LowM1998, refkey={C1968; PN2678}, title={A Collusion Problem and its Solution}, author={Steven H. Low and Nicholas F. Maxemchuk}, pages={158--182}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={Consider a group of colluders, each with certain knowledge such as the identity of some other colluders, some cryptographic keys, and some data, possibly multiply encrypted. Two colluders can combine their knowledge if their current knowledge satisfies certain conditions. Their cryptographic keys can help decrypt each other's encrypted data, expanding their knowledge and revealing more collusion opportunities, and the process of collusion continues. The question we address is whether it is possible for the colluders to uncover a target set of unencrypted data. In this paper we formulate the collusion problem and provide an algorithm that determines whether a collusion problem has a solution and, if so, computes one. A solution is a specific way by which the colluders can uncover the hidden information. The solution generated by our algorithm is generally not one that involves the minimum number of colluders. We show, however, that to find such a solution is NP-complete. Complex communication protocols employing cryptographic building blocks are being developed to transfer information among some users and hide from others. The algorithm presented here can be applied to determine whether and how a subset of protocol users can discover during or after the protocol's execution the information that is to be hidden from them.}, references={acmtcs::BurrowsAN1990, cacm::Chaum1981, ic::DolevEK1982, cacm::DenningS1981, ieeetit::DolevY1983, jcrypt::KemmererMM1994, cacm::NeedhamS1978, jcrypt::Simmons1994, crypto::TatebayashiMN1989} } @Article{Bar-NoyBHST1998, refkey={C1701; PN2677}, title={On Chromatic Sums and Distributed Resource Allocation}, author={Amotz Bar-Noy and Mihir Bellare and Magn{\'u}s M. Halld{\'o}rsson and Hadas Shachnai and Tami Tamir}, pages={183--202}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={This paper studies an optimization problem that arises in the context of distributed resource allocation: Given a conflict graph that represents the competition of processors over resources, we seek an allocation under which no two jobs with conflicting requirements are executed simultaneously. Our objective is to minimize the \emph{average response time} of the system. In alternative formulation this is known as the \emph{Minimum Color Sum} (\emph{MCS}) problem (E.~Kubicka and A.~J. Schwenk, 1989. An introduction to chromatic sums, \emph{in} ``Proceedings of the ACM Computer Science Conference,'' pp.~39--45.). We show that the algorithm based on finding iteratively a maximum independent set (\emph{MaxIS}) is a 4-approximation to the~MCS\@. This bound is tight to within a factor of~2. We give improved ratios for the classes of bipartite, bounded-degree, and line graphs. The bound generalizes to a $4\rho$-approximation of~MCS for classes of graphs for which the maximum independent set problem can be approximated within a factor of~$\rho$. On the other hand, we show that an $n^{1-\epsilon}$-approximation is NP-hard, for some $\epsilon > 0$. For some instances of the resource allocation problem, such as the \emph{Dining Philosophers}, an efficient solution requires \emph{edge} coloring of the conflict graph. We introduce the \emph{Minimum Edge Color Sum} (\emph{MECS}) problem which is shown to be NP-hard. We show that a 2-approximation to $\mathrm{MECS}(G)$ can be obtained distributively using \emph{compact coloring} within $O(\log^2 n)$ communication rounds.}, references={focs::AroraLMSS1992, focs::AwerbuchS1990, stoc::AwerbuchCS1994, soda::Bar-NoyMSS1995, ipl::blumK1997, stoc::Boppana1989, toplas::ChandyM1984, stoc::ChoyS1992, sctc::FeigeK1996, sicomp::GareyG1975, soda::GoldbergS1990, soda::IraniL1996, stoc::LundY1993, jcss::Lynch1981, stoc::NaorS1993, stoc::PanconesiS1992, sicomp::WangC1992} } @Article{FeigelsonH1998, refkey={C1876; PN2684}, title={Conjunctions of Unate {DNF} Formulas: Learning and Structure}, author={Aaron Feigelson and Lisa Hellerstein}, pages={203--228}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={A central topic in query learning is to determine which classes of Boolean formulas are efficiently learnable with membership and equivalence queries. We consider the class~$\mathcal{R}^k$ consisting of conjunctions of $k$-unate DNF formulas. This class generalizes the class of $k$-clause CNF formulas and the class of unate DNF formulas, both of which are known to be learnable in polynomial time with membership and equivalence queries. We prove that $\mathcal{R}^2$ can be properly learned in polynomial time with such queries if and only if $\mathrm{P} = \mathrm{NP}$. Thus the barrier to properly learning $\mathcal{R}^2$ with membership and equivalence queries is computational rather than informational. Few results of this type are known. In our proofs, we use recent results of Hellerstein \emph{et al}.\ (1997, \emph{J. Assoc.\ Comput.\ Mach.}\ \textbf{43}~(5), 840--862), characterizing the classes that are polynomial-query learnable, together with the work of Bshouty on the monotone dimension of Boolean functions. We extend some or our results to~$\mathcal{R}^k$ and pose open questions on learning DNF formulas of small monotone dimension. We also prove structure results for~$\mathcal{R}^k$. We construct, for any fixed~$k \ge 2$, a class of functions~$f$ that cannot be represented by any formula in~$\mathcal{R}^k$, but which cannot be ``easily'' shown to have this property. More precisely, for any function~$f$ on $n$~variables in the class, the value of~$f$ on any polynomial-size set of points in its domain is not a witness that~$f$ cannot be represented by a formula in~$\mathcal{R}^k$. Our construction is based on BCH codes.}, references={stoc::Angluin1992, jacm::AngluinHK1993, ic::Bshouty1995, colt::Hegedus1995, jacm::HellersteinPRW1996, colt::PillaipakkamnattR1994} } @Article{Bruggemann-KleinW1998, refkey={C1574; PN2688}, title={One-Unambiguous Regular Languages}, author={Anne Br{\"u}ggemann-Klein and Derick Wood}, pages={229--253}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={The ISO standard for the Standard Generalized Markup Language (SGML) provides a syntactic meta-language for the definition of textual markup systems. In the standard, the right-hand sides of productions are based on regular expressions, although only regular expressions that denote words unambiguously, in the sense of the ISO standard, are allowed. In general, a word that is denoted by a regular expression is witnessed by a sequence of occurrences of symbols in the regular expression that match the word. In an unambiguous regular expression as defined by Book \emph{et al}.\ (1971, \emph{IEEE Trans.\ Comput.}\ \textbf{C-20}(2), 149--153), each word has at most one witness. But the SGML standard also requires that a witness can be computed incrementally from the word with a one-symbol lookahead; we call such regular expressions \emph{$1$-unambiguous}. A regular language is a \emph{$1$-unambiguous language} if it is denoted by some 1-unambiguous regular expression. We give a Kleene theorem for 1-unambiguous languages and characterize 1-unambiguous regular languages in terms of structural properties of the minimal deterministic automata that recognize them. As a result we are able to prove the decidability of whether a given regular expression denotes a 1-unambiguous language; if it does, then we can construct an equivalent 1-unambiguous regular expression in worst-case optimal time.}, references={tcs::BerstelP1996, tcs::Bruggemann-Klein1993, stacs::Bruggemann-KleinW1992, jacm::Brzozowski1964, tcs::BerryS1986, tcs::ChangP1997:1, jcss::GinsburgH1967, sicomp::KnuthMP1977, actai::KintalaW1980, jcss::Leiss1981} } @Article{BorosIM1998, refkey={C1801; PN2687}, title={Error-Free and Best-Fit Extensions of Partially Defined {Boolean} Functions}, author={Endre Boros and Toshihide Ibaraki and Kazuhisa Makino}, pages={254--283}, journal=iandcomp, month={1~} # feb, year=1998, volume=140, number=2, abstract={In this paper, we address a fundamental problem related to the induction of Boolean logic: Given a set of data, represented as a set of binary ``true $n$-vectors'' (or ``positive examples'') and a set of ``false $n$-examples'' (or ``negative examples''), we establish a Boolean function (or an extension)~$f$, so that $f$~is true (resp., false) in every given true (resp., false) vector. We shall further require that such an extension belongs to a certain specified class of functions, e.g., class of positive functions, class of Horn functions, and so on. The class of functions represents our a~priori knowledge or hypothesis about the extension~$f$, which may be obtained from experience or from the analysis of mechanisms that may or may not cause the phenomena under consideration. \par The real-world data may contain errors, e.g., measurement and classification errors might come in when obtaining data, or there may be some other influential factors not represented as variables in the vectors. In such situations, we have to give up the goal of establishing an extension that is perfectly consistent with the given data, and we are satisfied with an extension~$f$ having the minimum number of misclassifications. \par Both problems, i.e., the problem of finding an extension within a specified class of Boolean functions and the problem of finding a minimum error extension in that class, will be extensively studied in this paper. For certain classes we shall provide polynomial algorithms, and for other classes we prove their NP-hardness.}, references={jcomp::AizensteinHHP1997, tcs::AmaldiK1995, ic::BiochI1995, sicomp::FischerS1992, jsyml::McKinsey1943, jacm::PittV1988, cacm::Valiant1984} } Volume 141, Number 1 February 25, 1998 @Article{BuntrockO1998, refkey={C1823; PN2681}, title={Growing Context-Sensitive Languages and {Church--Rosser} Languages}, author={Gerhard Buntrock and Friedrich Otto}, pages={1--36}, journal=iandcomp, month={25~} # feb, year=1998, volume=141, number=1, abstract={The growing context-sensitive languages are characterized by a nondeterministic machine model, the so-called \emph{shrinking two-pushdown automaton}. Then the deterministic version of this automaton is considered, and it is shown that it characterizes the class of \emph{generalized Church--Rosser languages}. As a consequence we obtain the result that the class of (generalized) Church--Rosser languages and the class of context-free languages are incomparable under set inclusion, thus verifying a conjecture of McNaughton \emph{et al}.\ (1988, \emph{J.~Assoc.\ Comput.\ Mach.}\ \textbf{35}, 324--344). Finally, we prove that each growing context-sensitive language is accepted in polynomial time by some one-way auxiliary pushdown automaton with a logarithmic space bound, which improves upon a result of Dahlhaus and Warmuth (1986, \emph{J.~Comput.\ System Sci.}\ \textbf{33}, 456--472).}, preliminary={STACS::BuntrockO1995}, references={icalp::BuntrockL1992, stacs::BuntrockL1994, actai::Book1978, jacm::Book1982, mfcs::Chytil1976, mfcs::Chytil1977, jcss::DahlhausW1986, jacm::GinsburgH1968, ic::Griffiths1968, focs::HartmanisIM1978, mfcs::JancarMP1993, mst::Knuth1968, ic::Loeckx1970, jacm::McNaughtonNO1988, jcss::Ruzzo1980, jacm::Sudborough1978, ic::Walters1970} } @Article{IwamaI1998, refkey={C1490; PN2685}, title={A Canonical Form of Vector Machines}, author={Kazuo Iwama and Chuzo Iwamoto}, pages={37--65}, journal=iandcomp, month={25~} # feb, year=1998, volume=141, number=1, abstract={We introduce RS-vector machines (RS-VMs) as a canonical form of vector machines. They are based on vector operations called \emph{repeat} and \emph{stretch}. \emph{Repeat} enlarges a vector $(a_1, a_2, \dots, a_m)$ to $(a_1, a_2, \dots, a_m, a_1, a_2, \dots, a_m)$ and \emph{stretch} enlarges $(a_1, a_2, \dots, a_m)$ to $(a_1, a_1, a_2, a_2, \dots, a_m, a_m)$ when the \emph{expansion factor}~$d(m) = 2$. \par It is shown that we can change the power of RS-VMs depending on this single parameter~$d(m)$: (i)~Polynomial-time RS-VMs of $d(m) = 2$ have the same power as polynomial-space TMs, and (ii)~polynomial-time RS-VMs of $d(m) = m$ have the same power as exponential-time, polynomial-alternation, alternating TMs. The more general results are: (iii)~RS-VMs of $d(m) = k$ ($k \ge 2$ is constant) have the same power as RS-VMs of $d(m) = 2$; (iv)~a wide variety of $d(m)$s such as $d(m) = m$, $m^2$, \ldots, $c m^k$, $2^m | m$, \ldots, $A(2,m) | m$, have at least the same power as $d(m) = m$, where $A(i, j)$ is Ackermann's function; and (v)~any polynomial~$d(m)$ in~$m$ cannot surpass the power of~$d(m) = m$.}, references={tcs::Berman1980, stoc::BertoniMS1981, jacm::ChandraKS1981, focs::HartmanisS1974, tcs::Kozen1980, stoc::PrattRS1974, jcss::PrattS1976, acmcs::QuinnD1984, stoc::Simon1977, focs::Simon1979} } @Article{MaassW1998, refkey={C1787; PN2686}, title={Efficient Learning with Virtual Threshold Gates}, author={Wolfgang Maass and Manfred K. Warmuth}, pages={66--83}, journal=iandcomp, month={25~} # feb, year=1998, volume=141, number=1, abstract={We reduce learning simple geometric concept classes to learning disjunctions over exponentially many variables. We then apply an online algorithm called Winnow whose number of prediction mistakes grows only logarithmically with the number of variables. The hypotheses of Winnow are linear threshold functions with one weight per variable. We find ways to keep the exponentially many weights of Winnow implicitly so that the time for the algorithm to compute a prediction and update its ``virtual'' weights is polynomial. \par Our method can be used to learn $d$-dimensional axis-parallel boxes when $d$ is variable and unions of $d$-dimensional axis-parallel boxes when $d$~is constant. The worst-case number of mistakes of our algorithms for the above classes is optimal to within a constant factor, and our algorithms inherit the noise robustness of Winnow. \par We think that other online algorithms with multiplicative weight updates whose loss bounds grow logarithmically with the dimension are amenable to our methods.}, references={colt::AuerKMW1996, stoc::AuerL1994, focs::AuerW1995, colt::Auer1993, jacm::blumerEHW1989, focs::BshoutyCH1994, apal::ChenH1996:143, colt::ChenM1992, colt::FrazierGMP1994, ieeetit::HausslerKW1997, ic::KivinenW1997, colt::Littlestone1989, colt::Littlestone1991, ic::LittlestoneW1994, colt::Vovk1990} } Volume 141, Number 2 March 15, 1998 @Article{AslamD1998, refkey={C1767; PN2664}, title={General Bounds on Statistical Query Learning and {PAC} Learning with Noise via Hypothesis Boosting}, author={Javed A. Aslam and Scott E. Decatur}, pages={85--118}, journal=iandcomp, month={15~} # mar, year=1998, volume=141, number=2, abstract={We derive general bounds on the complexity of learning in the statistical query (SQ) model and in the PAC model with classification noise. We do so by considering the problem of boosting the accuracy of weak learning algorithms which fall within the SQ model. This new model was introduced by Kearns to provide a general framework for efficient PAC learning in the presence of classification noise. We first show a general scheme for boosting the accuracy of weak SQ learning algorithms, proving that weak SQ learning is equivalent to strong SQ learning. The boosting is efficient and is used to show our main result of the first general upper bounds on the complexity of strong SQ learning. Since all SQ algorithms can be simulated in the PAC model with classification noise, we also obtain general upper bounds on learning in the presence of classification noise for classes which can be learned in the SQ model.}, references={stoc::Angluin1992:351, jacm::BlumerEHW1989:929, sicomp::HelmboldSW1992:240, stoc::Kearns1993:392, cacm::Valiant1984:1134} } @Article{SegalaGSL1998, refkey={C1822; PN2671}, title={Liveness in Timed and Untimed Systems}, author={Roberto Segala and Rainer Gawlick and J{\o}rgen S{\o}gaard-Andersen and Nancy Lynch}, pages={119--171}, journal=iandcomp, month={15~} # mar, year=1998, volume=141, number=2, abstract={When proving the correctness of algorithms in distributed systems, one generally considers \emph{safety} conditions and \emph{liveness} conditions. The Input/Output (I/O) automaton model and its timed version have been used successfully, but have focused on safety conditions and on a restricted form of liveness called fairness. In this paper we develop a new I/O automaton model, and a new timed I/O automaton model, that permit the verification of general liveness properties on the basis of existing verification techniques. Our models include a notion of \emph{receptiveness} which extends the idea of \emph{receptiveness} of other existing formalisms, and enables the use of compositional verification techniques. The presentation includes an \emph{embedding} of the untimed model into the timed model which preserves all the interesting attributes of the untimed model. Thus, our models constitute a \emph{coordinated framework} for the description of concurrent and distributed systems satisfying general liveness properties.}, references={tcs::AbadiL1991:253, toplas::AbadiL1993:73, toplas::AbadiL1994:1543, ipl::AlpernS1985:181, tcs::NicolaH1984:83, toplas::Lamport1994:872, ic::LynchS1989:81, ic::LynchV1995:214, ic::LynchV1996:1, ipl::RomijnV1996:245} } @Article{BezemKO1998, refkey={C1927; PN2683}, title={Diagram Techniques for Confluence}, author={Marc Bezem and Jan Willem Klop and Vincent van Oostrom}, pages={172--204}, journal=iandcomp, month={15~} # mar, year=1998, volume=141, number=2, abstract={We develop diagram techniques for proving confluence in abstract reductions systems. The underlying theory gives a systematic and uniform framework in which a number of known results, widely scattered throughout the literature, can be understood. These results include Newman's lemma, Lemma~3.1 of Winkler and Buchberger, the Hindley-Rosen lemma, the Request lemmas of Staples, the Strong Confluence lemma of Huet, the lemma of De~Bruijn.}, references={jacm::Huet1980, tcs::Oostrom1994, jacm::Rosen1973} } Volume 142, Number 1 April 10, 1998 @Article{Jouannaud1998, title={Preface}, author={Jean-Pierre Jouannaud}, pages={1}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1 } @Article{Kozen1998, refkey={C1713; PN2694}, title={Set Constraints and Logic Programming}, author={Dexter Kozen}, pages={2--25}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1, abstract={Set constraints are inclusion relations between expressions denoting sets of ground terms over a ranked alphabet. They are the main ingredient in set-based program analysis. In this paper we describe a constraint logic programming language \textsc{clp(sc)} over set constraints in the style of J.~Jaffar and J.-L. Lassez (1987, ``Proc.\ Symp.\ Principles of Programming Languages 1987,'' pp.~111--119). The language subsumes ordinary logic programs over an Herbrand domain. We give an efficient unification algorithm and operational, declarative, and fixpoint semantics. We show how the language can be applied in set-based program analysis by deriving explicitly the monadic approximation of the collecting semantics of N.~Heintze and J.~Jaffar (1992, ``Set Based Program Analysis''; 1990, ``Proc.\ 17th Symp.\ Principles of Programming Languages,'' pp.~197--209).}, references={ic::AikenKW1995:30, popl::AikenM1991, lics::AikenW1992, lics::BachmairGW1993, tcs::CardonC1982, lics::CharatonikP1994, lics::FruhwirthSVY1991, stacs::GilleronTT1993, focs::GilleronTT1993, popl::HeintzeJ1990, popl::JaffarL1987, popl::JonesM1979, pods::Kuper1987, popl::MishraR1985, sicomp::PaigeT1987, lics::Stefansson1994} } @Article{Michaylov1998, refkey={C1715; PN2693}, title={Repeated Redundant Inequalities in Constraint Logic Programming}, author={Spiro Michaylov}, pages={26--39}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1, abstract={Future redundant inequalities in a constraint logic program are those that are guaranteed to be subsumed after no more than one subsequent procedure call, whenever they are encountered at run time. It has been noted that such inequalities need only be tested for consistency with the current constraint set, thus resulting in dramatic savings in execution speed and space usage. Furthermore, they can be detected at compile time, leading to a valuable compiler optimization. By considering the role of such inequalities in a program, we generalize the notion of future redundancy in a number of ways and thus broaden its applicability. As a result, we show how to dramatically improve the performance of a wider class of programs that rely heavily on inequalities.}, references={popl::JaffarL1987, pldi::JaffarMSY1992, toplas::JaffarMSY1992, popl::MarriottS1993, pods::StuckeyS1994} } @Article{Charatonik1998, refkey={C1716; PN2692}, title={Set Constraints in Some Equational Theories}, author={Witold Charatonik}, pages={40--75}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1, abstract={Set constraints are relations between sets of ground terms over a given alphabet. They give a natural formalism for many problems in program analysis, type inference, order-sorted unification, and constraint logic programming. In this paper we start studies of set constraints in the environment given by equational specifications. We show that in the case of associativity (i.e., in free monoids) as well as in the case of associativity and commutativity (i.e., in commutative monoids) the problem of consistency of systems of set constraints is undecidable; in linear nonerasing shallow theories the consistency of systems of positive set constraints is NEXPTIME-complete and in linear shallow theories the problem for positive and negative set constraints is decidable.}, references={popl::AikenM1991, lics::AikenW1992, popl::AikenWL1994, lics::BachmairGW1993, lics::CharatonikP1994, focs::CharatonikP1994, lics::ComonHJ1992, ic::ComonHJ1994:154, cacm::Colmerauer1990, stacs::GilleronTT1993, focs::GilleronTT1993, lics::HeintzeJ1990, popl::HeintzeJ1990, popl::JonesM1979, ic::Kozen1998, jcss::Lewis1980, popl::MishraR1985, lics::Stefansson1994} } @Article{BackofenT1998, refkey={C1718; PN2691}, title={How to Win a Game with Features}, author={Rolf Backofen and Ralf Treinen}, pages={76--101}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1, abstract={We employ the model-theoretic method of Ehrenfeucht-Fr{\"\i}ss\'e games to prove the completeness of the theory~\emph{CFT}, which has been introduced by G.~Smolka and R.~Treinen (1994, \emph{J.\ Logic Programming} \textbf{18}(3), 229--258) for describing rational trees in a language of selector functions. The comparison to other techniques used in this field shows that Ehrenfeucht-Fr{\"\i}ss\'e Games lead to simpler proofs.}, references={tcs::Ait-KaciPS1994, tcs::BackofenS1995, jlogp::Backofen1995, ic::ComonD1994, jsymc::ComonL1989, tcs::ComonT1997, tcs::Courcelle1983, popl::JaffarL1987, lics::Maher1988, toplas::MartelliM1982, jlogp::SmolkaT1994, jlogp::smolka1992, mfcs::Treinen1993} } @Article{Lynch1998, refkey={C1719; PN2690}, title={Local Simplification}, author={Christopher Lynch}, pages={102--126}, journal=iandcomp, month={10~} # apr, year=1998, volume=142, number=1, abstract={We present a modification to the paramodulation inference system, where semantic equality and nonequality literals are stored as \emph{local simplifiers} with each clause. The local simplifiers are created when new clauses are generated an inherited by the descendants of that clause. Then the local simplifiers can be used to perform paramodulation and unit simplification, if certain conditions are satisfied. This reduces the search space of the theorem proving procedure and the length of the proofs obtained. In fact, we show that for ground SLD resolution with any selection rule, any set of clauses has a polynomial length proof. Without this technique, proofs may be exponential. We show that this process is sound, complete, and compatible with deletion rules (e.g., demodulation, subsumption, unit simplification, and tautology deletion), which do not have to be modified to preserve completeness. We also show the relationship between this technique and model elimination.}, references={jlogc::BachmairG1994, ic::BachmairGLS1995, jlogp::DowlingG1984, jacm::HsiangR1991, jacm::Loveland1968, tcs::LynchS1995, jsymc::NieuwenhuisR1995, jsymc::PaisP1990:3, sicomp::Peterson1983, jacm::WosRCS1967} } Volume 142, Number 2 May 1, 1998 @Article{Geffert1998, refkey={C1895; PN2682}, title={Bridging Across the {$\log(n)$} Space Frontier}, author={Viliam Geffert}, pages={127--158}, journal=iandcomp, month={1~} # may, year=1998, volume=142, number=2, abstract={This paper establishes the importance of even the lowest possible level of space bounded computations. We show that DLOG does not coincide with NLOG if and only if there exists a tally set in $\mathrm{NSPACE}(\log \log n)/\mathrm{DSPACE}(\log \log n)$. This result stands in perfect analogy to the related results concerning linear space or exponential time. Moreover, the above problem is equivalent to the existence of a function~$s(n)$, with arbitrarily slow or rapid growth rate, that is nondeterministically fully space constructible but cannot be constructed deterministically. We also present a ``hardest'' fully space constructible $s(n) \in O(\log \log n)$, a functional counterpart of log-space complete languages. These nonrelativized results are obtained by the use of oracle machines consuming much larger amount of space, in range between $n$ and~$2^{d \cdot n}$.}, preliminary={MFCS::Geffert1995}, references={ipl::AltGM1992, ipl::BertoniMP1994, mfcs::BertoniMP1995, tcs::RanjanCH1991:289, ic::DammH1996, jcss::FreedmanL1975, sicomp::Geffert1991, sicomp::Geffert1993, tcs::Hartmanis1990, ic::HartmanisIS1985, focs::StearnsHL1965:179, jacm::HopcroftU1969, sicomp::Immerman1988, sicomp::Iwama1993, ipl::KirsigL1987, stacs::LiskiewiczR1993, sicomp::LiskiewiczR1996, jcss::Savitch1970, tcs::Sipser1980, actai::Szelepcsenyi1988, ipl::Szepietowski1989, tcs::Szepietowski1990} } @Article{Thorup1998, refkey={C1833; PN2697}, title={All Structured Programs Have Small Tree-Width and Good Register Allocation}, author={Mikkel Thorup}, pages={159--181}, journal=iandcomp, month={1~} # may, year=1998, volume=142, number=2, abstract={The register allocation problem for an imperative program is often modeled as the coloring problem of the interference graph of the control-flow graph of the program. The interference graph of a flow graph~$G$ is the intersection graph of some connected subgraphs of~$G$. These connected subgraphs represent the lives, or life times, of variables, so the coloring problem models that two variables with overlapping life times should be in different registers. For general problems with unrestricted \textsf{gotos}, the interference graph can be any graph, and hence we cannot in general color within a factor~$O(n^\epsilon)$ from optimality unless $\mathrm{NP} = \mathrm{P}$. \par It is shown that if a graph has tree width~$k$, we can efficiently color any intersection graph of connected subgraphs within a factor $(\lfloor k/2 \rfloor + 1)$ from optimality. Moreover, it is shown that structured ($\equiv$\textsf{goto}-free) programs, including, for example, short circuit evaluations and multiple exits from loops, have tree width at most~6. Thus, for every structured program, we can do register allocation efficiently within a factor~4 from optimality, regardless of how many registers are needed. \par The bounded tree decomposition may be derived directly from the parsing of a structured program, and it implies that the many techniques for bounded tree width may now be applied in compiler optimization, solving problems in linear time that are NP-hard, or even P-space hard, for general graphs.}, references={jalgo::ArnborgLS1991, popl::BirkedalTV1996:171, sicomp::Bodlaender1996, tcs::Bodlaender1993, jalgo::BodlaenderGHK1995, soda::BodlaenderGT1998, algor::BoriePT1992, pldi::BriggsCKT1989, pldi::CallahanK1991, tcs::CourcelleM1993, tcs::DendrisKT1997, cacm::Dijkstra1968, sicomp::Gavril1972, pldi::GuptaSS1989, ipl::Halldorsson1993:19, soda::KannanP1995:360, acmcs::Knuth1974:261, jacm::LundY1994:960, ic::TofteT1997:109, actai::Wirth1971:35, cacm::Naur+1963:1} } @Article{Bruggemann-KleinW1998-dup, refkey={C1574; PN2688}, title={One-Unambiguous Regular Languages}, author={Anne Br{\"u}ggemann-Klein and Derick Wood}, pages={182--206}, journal=iandcomp, month={1~} # may, year=1998, volume=142, number=2, abstract={The ISO standard for the Standard Generalized Markup Language (SGML) provides a syntactic meta-language for the definition of textual markup systems. In the standard, the right-hand sides of productions are based on regular expressions, although only regular expressions that denote words unambiguously, in the sense of the ISO standard, are allowed. In general, a word that is denoted by a regular expression is witnessed by a sequence of occurrences of symbols in the regular expression that match the word. In an unambiguous regular expression as defined by Book \emph{et al}.\ (1971, \emph{IEEE Trans.\ Comput.}\ \textbf{C-20}(2), 149--153), each word has at most one witness. But the SGML standard also requires that a witness can be computed incrementally from the word with a one-symbol lookahead; we call such regular expressions \emph{$1$-unambiguous}. A regular language is a \emph{$1$-unambiguous language} if it is denoted by some 1-unambiguous regular expression. We give a Kleene theorem for 1-unambiguous languages and characterize 1-unambiguous regular languages in terms of structural properties of the minimal deterministic automata that recognize them. As a result we are able to prove the decidability of whether a given regular expression denotes a 1-unambiguous language; if it does, then we can construct an equivalent 1-unambiguous regular expression in worst-case optimal time.}, references={tcs::BerstelP1996, tcs::Bruggemann-Klein1993, stacs::Bruggemann-KleinW1992, jacm::Brzozowski1964, tcs::BerryS1986, tcs::ChangP1997:1, jcss::GinsburgH1967, sicomp::KnuthMP1977, actai::KintalaW1980, jcss::Leiss1981} } @Article{Veith1998, refkey={C1853; PN2696}, title={Succinct Representation, Leaf Languages, and Projection Reductions}, author={Helmut Veith}, pages={207--236}, journal=iandcomp, month={1~} # may, year=1998, volume=142, number=2, abstract={In this article, the following results are shown: 1.~For succinctly encoded problems~$s(A)$, completeness under polynomial time reductions is equivalent to completeness under projection reductions, an extremely weak reduction defined by a quantifier-free projective formula. 2.~The succinct version~$s(A)$ of a computation problem~$A$ is complete under projection reductions for the class of problems characterizable with leaf language~$A$, but not complete under \emph{monotone} projections. 3.~A strong conversion lemma: If $A$ is reducible to~$B$ in polylogarithmic time, then the succinct version of~$A$ is monotone projection reducible to the succinct version of~$B$. This results strengthens previous results by Papadimitriou and Yannakakis, and Balc\'azar and Lozano. It allows iterated application for multiple succinct problems. 4.~For all syntactic complexity classes there exists complete problems under \emph{monotone} projection reductions. This positively answers a question by Stewart for a large number of complexity classes.}, preliminary={sctc::Veith1996}, references={sicomp::AllenderBI1997:557, icalp::Balcazar1995, jcss::Barrington1989, jcss::BarringtonIS1990, sctc::Borchert1994, ipl::BorchertL1996, jcss::BovetCS1995:382, tcs::BovetCS1992, jcss::BrzozowskiK1978, mst::CronauerHVW1997, pods::EiterGM1994, ic::GalperinW1983, jsyml::Gottlob1997, mfcs::GottlobLV1995, sctc::HertrampfLSVW1993, mst::HertrampfVW1996, sicomp::Immerman1987, ic::ImmermanL1995, ic::JennerMT1996, mfcs::KowalukW1990:378, focs::Lengauer1982, jcss::LengauerW1992:63, ic::PapadimitriouY1986:181, jlogc::Stewart1991, jcss::Stewart1992, tcs::Stewart1993, jlogc::Stewart1994, stoc::Vardi1982, ipl::Veith1997, actai::Wagner1986} } @Article{Lafont1998, refkey={C2118; PN2721}, title={Erratum to ``{I}nteraction Combinators''}, author={Yves Lafont}, pages={237}, journal=iandcomp, month={1~} # may, year=1998, volume=142, number=2, references={Lafont1997} } Volume 143, Number 1 May 25, 1998 @Article{Severi1998, refkey={C1832; PN2708}, title={Type Inference for Pure Type Systems}, author={Paula Severi}, pages={1--23}, journal=iandcomp, month={25~} # may, year=1998, volume=143, number=1, abstract={In this paper we define a type inference semi-algorithm for singly sorted pure type systems. For that, we define the notion of pure type systems without the $\Pi$-condition and a mapping from pure type systems without the $\Pi$-condition to pure type systems. This allows us to prove the two main results: first that weak normalisation is preserved by the extension and second the correctness of the type inference semi-algorithm.}, references={jfp::CoquandH1994, popl::MeyerR1986, Jutting1993} } @Article{BolligW1998, refkey={C1945}, title={Completeness and Non-Completeness Results with Respect to Read-Once Projections}, author={Beate Bollig and Ingo Wegener}, pages={24--33}, journal=iandcomp, month={25~} # may, year=1998, volume=143, number=1, abstract={Several models of restricted branching programs or binary decision diagrams have a lot of applications in hardware verification. These models are investigated here from a complexity theoretical viewpoint. Because of depth restrictions projections are not suitable as reduction type and have to be restricted to read-once projections. Several types of polynomial-size binary decision diagrams have complete problems with respect to polynomial read-once projections. On the contrary it can be proved that the classes of polynomial-size decision trees and polynomial-size read-once branching programs or free binary decision diagrams do not have such complete problems.}, references={eccc::BolligSSW1994, tcs::BolligSSW1998, stacs::BolligW1996, acmcs::Bryant1992, tcs::SielingW1995, jacm::SkyumV1985} } @Article{Sangiorgi1998, refkey={C1930; PN2711}, title={An Interpretation of Typed Objects into Typed {$\pi$}-Calculus}, author={Davide Sangiorgi}, pages={34--73}, journal=iandcomp, month={25~} # may, year=1998, volume=143, number=1, abstract={An interpretation of Abadi and Cardelli's first-order function \emph{object calculus} into a typed $\pi$-calculus is presented. The interpretation validates the subtyping relation and the typing judgements of the object calculus and is computationally adequate. This is the first interpretation of a typed object-oriented language into a process calculus. The study intends to offer a contribution to understanding on the one hand, the relationship between $\pi$-calculus types and conventional types of programming languages and on the other hand, the usefulness of the $\pi$-calculus as a metalanguage for the semantics of typed object-oriented languages. \par The type language for the $\pi$-calculus has Pierce and Sangiorgi's I/O annotations, to separate the capabilities of reading and writing on a channel and \emph{variant types}. Technical contributions of the paper are the presentation of variant types for the $\pi$-calculus and their typing and subtyping properties, and an analysis of behavioural equivalences in a $\pi$-calculus with variant types.}, references={toplas::AmadioC1993:575, esop::AbadiC1994:1, facs::America1989:366, mscs::Milner1992:119, ic::MilnerPW1992:1, ic::MilnerPW1992:41, icalp::MilnerS1992:685, mscs::PierceS1996:409, lics::PierceS1993:376, ic::Walker1995:253, tacs::AbadiC1994:296, popl::AbadiCV1996, concur::Boreale1996, popl::FournetG1996, popl::GordonR1996, popl::Honda1996, concur::Jones1993, popl::Kamin1988, popl::KobayashiPT1996, concur::VasconcelosH1993} } @Article{Montagna1998, refkey={C1959; PN2714}, title={Investigations on Measure-one Identification of Classes of Languages}, author={Franco Montagna}, pages={74--107}, journal=iandcomp, month={25~} # may, year=1998, volume=143, number=1, abstract={We investigate the recursive identification of classes of r.e.\ languages on sets of texts of measure-one with respect to both fixed and variable probability distributions. In the case of fixed distributions, we give a characterization theorem, and we prove that, in the case of so-called canonical distributions, measure-one identification amounts to identification on informants. We also find analogues of some positive and negative results by Angluin in the case of variable distributions.}, references={ic::Angluin1980, ic::blumB1975, colt::JonghK1996, ic::Gold1967, jacm::Pitt1989, ic::PittS1988, tcs::WiehagenFK1984} } Volume 143, Number 2 June 15, 1998 Special Issue: Selections from 1992 IEEE Symposium on Logic in Computer Science (Part 1) @Article{Leivant1998:109, title={Preface}, author={Daniel Leivant}, pages={109}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, note={Part~2 of a Special Issue from the workshop on Logic and Computational Complexity (LCC), Indiana University, October 1994} } @Article{AbiteboulPV1998, refkey={C2096}, title={Reflective Relational Machines}, author={Serge Abiteboul and Christos H. Papadimitriou and V. Vianu}, pages={110--136}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, preliminary={lics::AbiteboulPV1994}, abstract={We propose a model of database programming with \emph{reflection} (dynamic generation of queries within the host programming language), called the \emph{reflective relational machine}, and characterize the power of this machine in terms of known complexity classes. In particular, the polynomial-time restriction of the reflective relational machine is shown to express PSPACE, and to correspond precisely to uniform circuits of polynomial depth and exponential size. This provides an alternative, logic-based formulation of the uniform circuit model, which may be more convenient for problems naturally formulated in logic terms, and establishes that reflection allows for more ``intense'' parallelism, which is not attainable otherwise (unless $\mathrm{P} = \mathrm{PSPACE}$). We also explore the power of the reflective relational machine subject to restrictions on the number of variables used, emphasizing the case of sublinear bounds.}, references={lics::AbiteboulV1989:71, stoc::AbiteboulV1991:209, jcss::AbiteboulV1995:309, jacm::AbiteboulVV1997:30, tcs::AbiteboulVV1995:101, pods::AfratiCY1991:13, jsyml::Barwise1977, popl::Chandra1981:50, jcss::ChandraH1982:99, jacm::ChandraKS1981:114, cacm::DeWittG1992:85, jcss::Immerman1982:76, ic::Immerman1986:86, sicomp::Immerman1987:760, sicomp::Immerman1989, stoc::KolaitisV1987:425, lics::KolaitisV1990:156, lics::KolaitisV1992:46, jcss::Leivant1989:51, jsyml::Poisat1982, jcss::PrattS1976:198, pods::Ross1992:346, dpd::Valduriez1993:137, pods::BusscheGV1993:17, stoc::Vardi1982:137} } @Article{Constable1998, refkey={C2110; PN2719}, title={A Note on Complexity Measures for Inductive Classes in Constructive Type Theory}, author={Robert L. Constable}, pages={137--153}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, abstract={It is notoriously hard to express computational complexity properties of programs in programming logics based on a semantics which respects extensional function equality. That is a serious impediment to applications of programming logics requiring reasoning about complexity. This paper shows how to use existing mechanisms to define internal computational complexity measures in logics that support inductively defined types, dependent products, and functions. The method exploits a feature of inductive definitions in constructive type theory, namely that implicit proof codes are kept with the objects showing how they are presented in the inductive class. The idea is illustrated by giving a formal inductive definition of \emph{PTime} based on ideas from Leivant's work and on Bellantoni and Cook's approach. Then a complexity measure is defined on elements of this class. This paper discusses the limitations of this idea and the need for \emph{faithfulness} guarantees that link internal complexity classes to the implementation of the logic. The paper concludes with a definition of \emph{resource bounded logics} and a discussion of interesting lines of investigation of these logics which have the potential to make practical uses of results from computational complexity theory in formal reasoning about the efficiency of programs.}, references={jfp::AbadiCCL1991:375, lics::Allen1987:215, lics::AllenCHA1990:95, toplas::BatesC1985:113, cc::BellantoniC1992:97, sctc::Buss1986:77, stoc::Constable1973:108, lics::ConstableC1998, apal::CookU1993:103, stoc::CookU1989:107, tcs::GirardSS1992:1, jacm::HartmanisH1971:444, lics::Howe1991:162, sicomp::Immerman1987:760, ic::Leivant1994:391, stoc::McCreightM1969, jcss::Mehlhorn1976:147, popl::MorrisettWCG1998, sicomp::Scott1976:522, lics::Seth1992:286, lics::Seth1993:320, lics::ConstableS1987:183} } @Article{Dawar1998, refkey={C2098}, title={A Restricted Second Order Logic for Finite Structures}, author={Anuj Dawar}, pages={154--174}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, abstract={We introduce a restricted version of second order logic~$\mathrm{SO}^\omega$ in which the second order quantifiers range over relations that are closed under the equivalence relation~$\equiv^k$ of $k$ variable equivalence, for some~$k$. This restricted second order logic is an effective fragment of the infinitary logic~$L^\omega_{\infty\omega}$, but it differs from other such fragments in that it is not based on a fixed point logic. We explore the relationship of~$\mathrm{SO}^\omega$ with fixed point logics, showing that its inclusion relations with these logics are equivalent to problems in complexity theory. We also look at the expressibility of NP-complete problems in this logic.}, references={jacm::AbiteboulVV1997:30, jcss::AbiteboulV1991:62, jcss::AbiteboulV1995:309, jsyml::Barwise1977, jcss::ChandraH1982:99, lics::DawarG1995:54, ic::DawarLW1995:160, apal::GurevichS1986, jcss::Immerman1982:76, ic::Immerman1986:86, lics::KolaitisV1992:46, ic::KolaitisV1992:258, ic::Leivant1990:95, tcs::Stockmeyer1976:1, stoc::Vardi1982:137} } @Article{Girard1998, refkey={C2095}, title={Light Linear Logic}, author={Jean-Yves Girard}, pages={175--204}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, abstract={The abuse of structural rules may have damaging complexity effects.}, references={tcs::Girard1987:1, tcs::GirardSS1992:1, lics::HillebrandKM1993:332, ic::Leivant1994:391} } @Article{IshiharaKN1998, refkey={C2099}, title={Computable {Kripke} Models and Intermediate Logics}, author={Hajime Ishihara and Bakhadyr Khoussainov and Anil Nerode}, pages={205--230}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, abstract={We introduce effectiveness considerations into model theory of intuitionistic logic. We investigate effectiveness of completeness (by Kripke) results for intermediate logics such as intuitionistic logic, classical logic, constant domain logic, directed frames logic, and Dummett's logic.}, references={jsyml::Gabbay1976, apal::IshiharaKN1998, jsyml::MinariTO1990:1099} } @Article{Lindell1998, refkey={C2097}, title={A Constant-Space Sequential Model of Computation for First-Order Logic}, author={Steven Lindell}, pages={231--250}, journal=iandcomp, month={15~} # jun, year=1998, volume=143, number=2, abstract={We define and justify a natural sequential model of computation with a constant amount of read/write work space, despite unlimited (polynomial) access to read-only input and write-only output. The model is deterministic, uniform, and sequential. The constant work space is modeled by a finite number of destructively read boolean variables, assignable by formulas over the canonical boolean operations. We show that computation on this model is equivalent to expressibility in first-order logic, giving a duality between (read-once) constant-space serial algorithms and constant-time parallel algorithms.}, references={sicomp::AllenderBI1997:557, ipl::AllenderG1991:89, jcss::BarringtonCST1992:478, jcss::BarringtonIS1990:274, jlogc::Dawar1995:213, ipl::IstrailZ1994:211, mst::FurstSS1984, sicomp::Immerman1989, ic::ImmermanL1995, sctc::Lindell1992} } Volume 144, Number 1 July 10, 1998 @Article{AmirBF1998, refkey={C1422}, title={Optimal Parallel Two Dimensional Text Searching on a {CREW PRAM}}, author={Amihood Amir and Gary Benson and Martin Farach}, pages={1--17}, journal=iandcomp, month={10~} # jul, year=1998, volume=144, number=1, abstract={We present a parallel algorithm for two dimensional text searching over a general alphabet. This algorithm is optimal in two ways. First, the total number of operations on the text is linear. Second, the algorithm takes time $O(\log m)$ on a CREW PRAM (where $m$ is the length of the longest dimension of the pattern), thus matching the lower bound for string matching on a PRAM without concurrent writes. On a CRCW, the algorithm runs in time $O(\log \log m)$.}, references={soda::AmirB1992, stoc::AmirBF1992, spaa::AmirBF1993, icalp::AmirBF1994, cacm::AhoC1975, sicomp::Baker1978, sicomp::BreslauerG1990, ipl::Bird1977, cacm::BoyerM1977, focs::ColeCGGHMPR1993, sicomp::CookDR1986, sicomp::FichRW1988, stoc::Galil1992, focs::GalilP1992, spaa::KedemLP1989, sicomp::KnuthMP1977, icalp::Vishkin1985, sicomp::Vishkin1991} } @Article{Hoepman1998, refkey={C1777}, title={Self-Stabilizing Ring-Orientation Using Constant Space}, author={Jaap-Henk Hoepman}, pages={18--39}, journal=iandcomp, month={10~} # jul, year=1998, volume=144, number=1, abstract={The ring-orientation problem requires all processors on an anonymous ring to reach agreement on a direction along the ring. A self-stabilizing ring-orientation protocol eventually ensures that all processors on the ring agree on a direction, regardless of the initial states of the processors on which the protocol is started. In this paper we present two uniform deterministic self-stabilizing ring-orientation protocols with rings with an odd number of processors using only a constant number of states per processor. The first protocol operates in the link-register model under the distributed daemon, and the second protocol operates in the state-reading model under the central daemon. Both protocols do not assume an upper bound on the length of the ring and are therefore applicable to dynamic rings. As an application of our techniques we are able to prove that under the central daemon on an odd-length ring, the link-register model and the state-reading model are equivalent in the sense that any self-stabilizing protocol for the one model can be transformed to an equivalent, self-stabilizing protocol in the other model.}, references={jacm::AttiyaSW1988, toplas::BurnsP1989, cacm::Dijkstra1974, actai::GoudaHR1989:697, ipl::Herman1990, ic::IsraeliJ1993} } @Article{GireH1998, refkey={C1947}, title={An Extension of Fixpoint Logic with a Symmetry-Based Choice Construct}, author={F. Gire and H. K. Hoang}, pages={40--65}, journal=iandcomp, month={10~} # jul, year=1998, volume=144, number=1, abstract={We propose a mechanism of restricted non-determinism in logical languages that uses a so-called symmetry-based choice operator whose application is restricted only on symmetric elements. Based on this mechanism, we define a logical language that is PTIME but strictly more expressive than fixed-point logic with counting. This language is based, on the one hand, on an extension of the inflationary fixed-point logic with a choice operator, called specified symmetry choice, and, on the other hand, on an introduction of a so-called logical reduction operator, which when added to the above extension of fixpoint logic, allows us to increase the expressive power.}, references={stoc::AbiteboulV1991, focs::CaiFI1989, jcss::ChandraH1980, jcss::ChandraH1982, icalp::GyssensBG1994, focs::GurevichS1985:346, icdt::GrumbachT1992, jcss::Immerman1982, ic::Immerman1986, sicomp::Immerman1987, lics::KolaitisV1992, stoc::Vardi1982, pods::BusscheG1992} } @Article{FrancesL1998, refkey={C1727}, title={Optimal Mistake Bound Learning is Hard}, author={Moti Frances and Ami Litman}, pages={66--82}, journal=iandcomp, month={10~} # jul, year=1998, volume=144, number=1, abstract={This paper provides evidence that there is no polynomial-time optimal mistake bound learning algorithm. This conclusion is reached via several reductions as follows. \par Littlestone (1988, \emph{Mach.\ Learning}~\textbf{2}, 285--318) has introduced a combinatorial function~$K$ from classes to integers and has shown that if a subroutine computing~$K$ is given, one can construct a polynomial-time optimal MB learning algorithm as a subroutine, one can compute~$K$ in polynomial time. Our result combines with Littlestone's to establish that the two tasks above have the same time complexity up to a polynomial. \par Next, we show that the VC-dimension decision problem is polynomially reducible to the $K$-decision problem. Papadimitriou and Yannakakis~[PY93] have a provided strong evidence that the VC-dimension decision problem is not in~$\mathrm{P}$. Therefore, it is very unlikely that there is a polynomial-time optimal mistake bound learning algorithm.}, references={jacm::BlumerEHW1989:929, ipl::HyafilR1976:15, sctc::PapadimitriouY1993:12, cacm::Valiant1984:1134} } Volume 144, Number 2 August 1, 1998 @Article{BernardoDG1998, refkey={C2059}, title={A Formal Approach to the Integration of Performance Aspects in the Modeling and Analysis of Concurrent Systems}, author={Marco Bernardo and Lorenzo Donatiello and Roberto Gorrieri}, pages={83--154}, journal=iandcomp, month={1~} # aug, year=1998, volume=144, number=2, abstract={A formal approach for modeling and analyzing concurrent systems is proposed which integrates performance characteristics in the early stages of the design process. The approach relies on both stochastically timed process algebras and stochastically timed Petri nets in order to exploit their complementary advantages. The approach is instantiated to the case of EMPA (extended Markovian process algebra), introduced together with the collection of its four semantics and the notion of equivalence that are required in order to implement the approach. Finally, the case study of the alternating bit protocol is presented to illustrate the adequacy of the approach.}, references={ieeetse::MarsanBBCCC1989:832, acmtcs::MarsanCB1984:93, icalp::Bernardo1997:358, tcs::BernardoG1998, cacm::BartlettSW1969:260, toplas::CleavelandPS1993:36, actai::DeganoNM1988:59, ieeetse::Ferrari1986:678, tcs::HennessyL1995:353, ic::LarsenS1991:1, facs::Tofts1994:536, tcs::VissersSSB1991:179} } @Article{EiterIM1998, refkey={C1972}, title={Double {Horn} Functions}, author={Thomas Eiter and Toshihide Ibaraki and Kazuhisa Makino}, pages={155--190}, journal=iandcomp, month={1~} # aug, year=1998, volume=144, number=2, abstract={In this paper, we define double Horn functions, which are the Boolean functions~$f$ such that both $f$ and its complement (i.e., negation) $\bar{f}$ are Horn, and investigate their semantical and computational properties. Double Horn functions embody a balanced treatment of positive and negative information in the course of the extension problem of partially defined Boolean functions (pdBfs), where a pdBf is a pair~$(T, F)$ of disjoint sets $T, F \in \{0, 1\}^n$ of true and false vectors, respectively, and an extension of~$(T, F)$ is a Boolean function~$f$ that is compatible with~$T$ and~$F$. We derive syntactic and semantic characterizations of double Horn functions, and determine the number of such functions. The characterizations are then exploited to give polynomial time algorithms (i)~that recognize double Horn functions from Horn DNFs (disjunctive normal form), and (ii)~that compute the prime DNF from an arbitrary formula, as well as its complement and its dual. Furthermore, we consider the problem of determining a double Horn extension of a given pdBf. We describe a polynomial time algorithm for this problem and moreover an algorithm that enumerates all all double Horn extensions of a pdBf with polynomial delay. However, finding a shortest double Horn extension (in terms of the size of a formula~$\varphi$ representing it) is shown to be intractable.}, references={focs::AngluinFP1990:186, ipl::BlumerEHW1987:377, jlogp::DowlingG1984:267, actai::Eiter1995:171, tcs::EkinHP1997:257, ipl::HammerK1992:23, tkde::HammerK1995:751, sicomp::HuntS1990:44, ipl::JohnsonYP1988:119, aaai::KautzKS1993:34, jcss::Makowsky1987:266, tcs::Mundici1989:113, jacm::PittV1988:965, aaai::SelmanK1991:904, cacm::Valiant1984:1134, ic::BorosIM1998, jsyml::Horn1951, jsyml::McKinsey1943} } Volume 145, Number 1 August 25, 1998 @Article{DrewesE1998, refkey={C1967}, title={Decidability of the Finiteness of Ranges of Tree Transductions}, author={Frank Drewes and Joost Engelfriet}, pages={1--50}, journal=iandcomp, month={25~} # aug, year=1998, volume=145, number=1, abstract={The finiteness of ranges of tree transductions is shown to be decidable for~$\mathrm{TBY}^+$, the composition closure of macro tree transductions. Furthermore, $\mathrm{TBY}^+$ definable sets and $\mathrm{TBY}^+$ computable relations are considered, which are obtained by viewing a tree as an expression that denotes an element of a given algebra. A sufficient condition on the considered algebra is formulated under which the finiteness problem is decidable for $\mathrm{TBY}^+$ definable sets and for the ranges of $\mathrm{TBY}^+$ computable relations. The obtained result applies in particular to the class of string languages that can be defined by $\mathrm{TBY}^+$ transductions via the yield mapping. This is a large class which is proved to form a substitution-closed full~AFL.}, references={ic::AhoU1971, sicomp::Baker1978, ic::Baker1978, ic::Baker1979, tcs::CourcelleF1982:163, tcs::CourcelleF1982:235, tcs::courcelleM1993, tcs::Damm1982, mst::DanyiF1996, ic::DammG1986, jcss::Drewes1996, mst::Engelfriet1975, mst::Engelfriet1977, ipl::Engelfriet1978, mst::Engelfriet1982, ic::Engelfriet1991, caap::engelfriet1994, jcss::EngelfrietS1977, jcss::EngelfrietS1978, jcss::engelfrietV1985, actai::EngelfrietV1988, mst::FulopV1989, tcs::GyenizseV1996, tcs::HabelKV1991, mst::JonesS1979, jcss::Maibaum1974, ic::MezeiW1967, mst::Rounds1970, stoc::rounds1970, mst::Seidl1994, tcs::Seidl1994, tcs::SlutzkiV1995, jcss::Thatcher1970, ic::Vogler1988, ic::Wanke1994} } @Article{Honkala1998, refkey={C2009}, title={On Number Systems with Finite Degree of Ambiguity}, author={Juha Honkala}, pages={51--63}, journal=iandcomp, month={25~} # aug, year=1998, volume=145, number=1, abstract={We show that it is decidable whether or not a given $n$-recognizable set is representable by a number system having finite degree of ambiguity. As a corollary we obtain an algorithm for computing the degree of ambiguity of a given set defined by a number system.}, references={mst::Cobham1969:186, ic::CulikS1983:139, ic::Frougny1988:233, mst::Frougny1992:37, tcs::Honkala1984:61, jucs::Honkala1995:648, tcs::LucaR1986:265, tcs::MaurerSW1983:331, ic::Shallit1994:331} } @Article{HartonasH1998, refkey={C2032; PN2723}, title={Full Abstractness for a Functional/Concurrent Language with Higher-Order Value-Passing}, author={Chrysafis Hartonas and Matthew Hennessy}, pages={64--106}, journal=iandcomp, month={25~} # aug, year=1998, volume=145, number=1, abstract={We study an applied typed call-by-value $\lambda$-calculus which in addition to the usual types for higher-order functions contains an extra type called~\textsf{proc}, for processes; the constructors for terms of this type are similar to those found in standard process calculi such as~CCS. \par We first give an operational semantics for this language in terms of a labeled transition system which is then used to give a behavioral preorder based on contexts; the expression~\textsf{N} dominates~\textsf{M} if in every appropriate context if \textsf{M} can produce a boolean value then so can~\textsf{N}. \par Based on standard domain constructors we define a model, a prime algebraic lattice, which is \emph{fully abstract} with respect to this behavior preorder; expressions are related in the model if and only if they are related behaviorally. \par The proof method uses concepts that are of independent interest. It involves characterizing the domain using filters of a property logic for program expressions and developing a program logic for relating program expressions with property formulae.}, references={ic::Abramsky1991:161, apal::Abramsky1991:1, ic::Boudol1994:51, jsyml::BarendregtCD1983, mscs::DamianiDG1999, mfcs::Dezani-CiancaglinidP1993:403, mfcs::FerreiraH1995:454, popl::FournetG1996:372, popl::FournetG1996:372, lics::Jeffrey1995:255, tcs::Hartonas1998, ic::Hennessy1994:55, icalp::Hennessy1994:286, tcs::Larsen1990:265, ic::MilnerPW1992:1, ic::MilnerPW1992:41, ic::Moggi1991:55, sicomp::Plotkin1976:452, tcs::Plotkin1977:223, pldi::Reppy1991:293, pldi::Reppy1991, ic::Sangiorgi1994:120, lics::Stark1996:36, tcs::Stirling1985:27, tcs::Stirling1987:311, actai::Thomsen1993:1} } Volume 145, Number 2 September 15, 1998 @Article{HermidaJ1998, refkey={C2021; PN2725}, title={Structural Induction and Coinduction in a Fibrational Setting}, author={Claudio Hermida and Bart Jacobs}, pages={107--152}, journal=iandcomp, month={15~} # sep, year=1998, volume=145, number=2, abstract={We present a categorical logic formulation of induction and coinduction principles for reasoning about inductively and coinductively defined types. Our main results provide sufficient criteria for the validity of such principles: in the presence of comprehension, the induction principle for initial algebras is admissible, and dually, in the presence of quotient types, the coinduction principle for terminal coalgebras is admissible. After giving an alternative formulation of induction in terms of binary relations, we combine both principles and obtain a mixed induction/coinduction principle which allows us to reason about minimal solutions $X \cong \sigma(X)$ where $X$ may occur both positively and negatively in the type constructor~$\sigma$. We further strengthen these logical principles to deal with contexts and prove that such strengthening is valid when the (abstract) logic we consider is contextually functionally complete. All the main results follow from a basic result about adjunctions between ``categories of algebras'' (inserters).}, references={jcss::AmericaR1989:343, ic::ArbibM1982:139, mscs::Cockett1993:277, tcs::CockettS1995:69, ic::CroleP1992:171, lics::Ehrhard1988, ic::Fiore1996:186, mscs::HermidaJ1995:501, tcs::Jacobs1993:169, apal::Jacobs1994:73, mst::LehmannS1981:97, ndjfl::Makkai1993:334, ndjfl::Makkai1993:471, tcs::Markowsky1977:125, tcs::Pitts1994:195, ic::Pitts1996:66, mscs::Reichel1995:129, sicomp::SmythP1982:761} } @Article{GiacobazziR1998, refkey={C1989; PN2724}, title={Uniform Closures: Order-Theoretically Reconstructing Logic Program Semantics and Abstract Domain Refinements}, author={Roberto Giacobazzi and Francesco Ranzato}, pages={153--190}, journal=iandcomp, month={15~} # sep, year=1998, volume=145, number=2, abstract={The notion of uniform closure operator is introduced, and it is shown how this concept surfaces in two different areas of application of abstract interpretation, notably in semantics design for logic programs and in the theory of abstract domain refinements. In logic programming, uniform closures permit generalization, from an order-theoretic perspective, of the standard hierarchy of declarative semantics. In particular, we show how to reconstruct the model-theoretic characterization of the well-known s-semantics using pure order-theoretic concepts only. As far as the systematic refinement operators on abstract domains are concerned, we show that uniform closures capture precisely the property of a refinement of being invertible, namely of admitting a related operator that simplifies as much as possible a given abstract domain of input for that refinement. Exploiting the same argument used to reconstruct the s-semantics of logic programming, we yield a precise relationship between refinements and their inverse operators: we demonstrate that they form an adjunction with respect to a conveniently modified complete order among abstract domains.}, references={toplas::BarbutiGL1993:133, jacm::BolG1996:863, jlogp::BossiC1993:47, jlogp::BossiGLM1994:149, tcs::BossiGLM1994:3, tcs::CodishDY1994:93, toplas::CodishMBBH1995:28, toplas::CortesiFGPR1997, popl::CortesiCH1994:227, acmcs::Cousot1996:324, popl::Cousot1997:316, popl::CousotC1977:238, popl::CousotC1979:269, jlogp::CousotC1992:103, popl::CousotC1992:83, popl::CousotC1992:83, jacm::EmdenK1976, alp::FagesG1996:77, tcs::FalaschiLPM1989:289, ic::FalaschiLMP1993:86, acmcs::FileGR1996:333, tcs::FileR1999, stacs::Giacobazzi1996:503, alp::GiacobazziR1996:238, icalp::GiacobazziR1997:771, scp::GiacobazziR1998, cacm::HoareHJMRSSSS1987:672, toplas::Jensen1997, tcs::LassezM1984:167, popl::YiH1993} } @Article{Corradini1998, refkey={C1975; PN2726}, title={On Performance Congruences for Process Algebras}, author={Flavio Corradini}, pages={191--230}, journal=iandcomp, month={15~} # sep, year=1998, volume=145, number=2, abstract={Based on the hypothesis of durational actions and process synchronization with ``busy waiting'' mechanism, \emph{performance equivalence} has been proposed to introduce a simple form of performance evaluation in process algebras. This equivalence enjoys many of the pleasant properties of those in the untimed setting but it is not a congruence for parallel composition with synchronization. In this paper we give a bisimulation-based characterization of the coarsest congruence contained within performance equivalence (and discuss alternative formulations). This problem was left open in several papers. We study how the new equivalence, called \emph{performance congruence}, related with other closed equivalences in the literature and show that, unlike other proposals, it is a natural extension of those standard in the untimed setting. The weak version of performance congruence, which abstracts from internal details, is also studied. A number of examples of processes related or taken apart by performance congruence, and its weak version, are provided. A nontrivial one is also presented to illustrate the utility of the new congruences. The paper concludes with further observations concerning performance congruence and with a discussion on related and further interesting work.}, references={concur::AcetoM1993:97, actai::AcetoM1996:317, facs::BaetenB1991:142, facs::BoudolCHK1994:165, lics::NatarajanC1996:63, lics::CleavelandZ1991:110, mfcs::CorradiniGR1995:444, actai::CorradiniGR1997:805, mfcs::CorradiniP1996:279, icalp::DarondeauD1989:234, tcs::NicolaH1984:83, tcs::GorrieriRS1995:73, tcs::HennessyL1995:353, ic::HennessyR1995:221, concur::Klusener1991:376, actai::Arun-KumarH1992:737, icalp::MilnerS1992:685, concur::MollerT1990:401, concur::MollerT1991:424, icalp::MontanariY1992:617, sicomp::PaigeT1987, tcs::ReedR1988:249, ic::Vogler1995:149, concur::Yi1990:502} } Volume 146, Number 1 October 10, 1998 @Article{BlundoSHKVY1998, refkey={C1659; PN2717}, title={Perfectly Secure Key Distribution for Dynamic Conferences}, author={Carlo Blundo and Alfredo De Santis and Amir Herzberg and Shay Kutten and Ugo Vaccaro and Moti Yung}, pages={1--23}, journal=iandcomp, month={10~} # oct, year=1998, volume=146, number=1, abstract={In this paper we analyze perfectly secure key distribution schemes for dynamic conferences. In this setting, \emph{any} member of a group of $t$ users can compute a common key using only his private initial piece of information and the \emph{identities} of the other $t - 1$ users in the group. Keys are secure against coalitions of up to $k$~users; that is, even if $k$ users pool together their pieces they cannot compute anything about a key of any conference comprised of $t$ other users. First we consider a noninteractive model where users compute the common key without any interaction. We prove the tight bound on the size of each user's piece of information of $\binom{k+t-1}{t-1}$ times the size of the common key. Then, we consider the model where interaction is allowed in the common key computation phase and show a \emph{gap} between the models by exhibiting a one-round interactive scheme in which the user's information is only $k + t - 1$ times the size of the common key. Finally, we present its adaptation to network topologies with neighbourhood constraints and to asymmetric (e.g., client-server) communication models.}, references={crypto::BeimelC1993:444, crypto::BirdGHJKMY1991:44, eurocrypt::Blom1984:335, eurocrypt::BlundoC1994:287, eurocrypt::BlundoC1994:287, crypto::BrickellLY1987:418, crypto::FiatN1993:480, crypto::FischerW1991:141, crypto::FumyM1990:274, jcrypt::GongW1990:51, stoc::ImpagliazzoR1989:44, crypto::KoyamaO1987:175, crypto::LeightonM1993:456, crypto::MatsumotoI1987:185, jcrypt::McCurley1988:95, eurocrypt::MaurerY1991:498, cacm::Merkle1978:294, cacm::NeedhamS1978:993, crypto::Shamir1984:47, crypto::TsujiiC1991:288, crypto::Yacobi1990:268, crypto::YacobiS1989:344} } @Article{FokkinkV1998, refkey={C1843; PN2729}, title={A Conservative Look at Operational Semantics with Variable Binding}, author={Wan Fokkink and Chris Verhoef}, pages={24--54}, journal=iandcomp, month={10~} # oct, year=1998, volume=146, number=1, abstract={We set up a formal framework to describe transition system specifications in the style of Plotkin. This framework has the power to express many-sortedness, general binding mechanisms, and substitutions, among other notions such as negative hypotheses and unary predicates on terms. The framework is used to present a conservativity format in operational semantics, which states sufficient criteria to ensure that the extension of a transition system specification with new transition rules does not affect the semantics of the original terms.}, references={lics::AllenCHA1990, facs::BaetenB1991, tcs::BaetenB1991, concur::BaetenB1992, facs::BaetenB1996, concur::BaetenV1993, lics::Bernstein1998, tcs::Bloom1995, jacm::BloomIM1995, jacm::bolG1996, tcs::DArgenioV1997, ic::FokkinkG1996, ic::FokkinkK1995, jacm::GelderRS1991, icalp::Glabbeek1996, tcs::Groote1993, ic::GrooteV1992, ic::Hennessy1994, ic::HennessyI1993, ic::Howe1996, concur::MilnerPW1991, ic::MilnerPW1992:1, ic::MilnerPW1992:41, ic::NicollinS1994, concur::MollerT1990, ic::Sangiorgi1994, ic::Schneider1995, tcs::Simone1985, tcs::Stoughton1988, njc::Verhoef1995} } @Article{MacielT1998, refkey={C1919; PN2732}, title={Threshold Circuits of Small Majority-Depth}, author={Alexis Maciel and Denis Th{\'e}rien}, pages={55--83}, journal=iandcomp, month={10~} # oct, year=1998, volume=146, number=1, abstract={Constant-depth polynomial-size threshold circuits are usually classified according to their total depth. For example, the best known threshold circuits for iterated multiplication and division have depths four and three, respectively. In this paper, the complexity of threshold circuits is investigated from a different point of view: explicit AND, OR gates are allowed in the circuits, and a threshold circuit is said to have majority-depth~$d$ if no path traverses more than $d$ threshold gates. It is then shown that iterated multiplication can be computed by polynomial-size threshold circuits of total depth five but of majority-depth three. Circuits of depth four and majority-depth two are obtained for division and powering. These results rely on a careful implementation of iterated addition and Chinese remaindering. In addition, a simple symbolic calculus for composing circuit classes is developed: this notation allows for a concise and elegant presentation of the results.}, references={apal::Ajtai1983:1, stoc::AjtaiB1984, sicomp::BeameCH1986:994, cc::Beigel1994:314, sctc::Beigel1993:82, cc::BeigelT1994:350, focs::BruckS1990:632, sicomp::ChandraSV1984:423, ic::DenenbergGS1986:216, tcs::FaginKPS1985:239, mst::FurstSS1984:13, cc::GoldmannHR1992:277, stoc::GoldmannK1993:551, jcss::HajnalMPST1993:129, ipl::HofmeisterHK1991:219, ic::ImmermanL1995:103, stacs::MacielT1993:545, sctc::Reif1987:118, stoc::Sipser1983:61, IEEETIT::SiuBKH1993, stoc::Smolensky1987:77, focs::Yao1985:1, stacs::ZhangBT1993} } Volume 146, Number 2 November 1, 1998 @Article{FerraginaL1998, refkey={C2013; PN2733}, title={Dynamic Dictionary Matching in External Memory}, author={Paolo Ferragina and Fabrizio Luccio}, pages={85--99}, journal=iandcomp, month={1~} # nov, year=1998, volume=146, number=2, abstract={In the \emph{dynamic dictionary matching} problem, a dictionary~$D$ contains a set of patterns that can change over time under insertion and deletion of individual patterns. Given an arbitrary text~$T$, we must efficiently list all the dictionary patterns that occur at each text position. We investigate the I/O complexity of this problem for a large dictionary that must be stored in external storage devices. By following a completely new approach, we devise an efficient solution which is based upon the SB-tree data structure (P.~Ferragina and R.~Grossi, 1995, \emph{in} ``Proc.\ ACM Symposium on Theory of Computing,'' pp.~693--702), and a novel notion of certificate for the dictionary matching problem. Our data structure can be adapted to efficiently work in main memory and to solve other problems, thus providing a new insight into the nature of the dictionary matching problem.}, references={cacm::AhoC1975, focs::AmirF1991, jcss::AmirFGGP1994, ic::AmirFIPS1995, ipl::AmirFM1994, jcss::Baker1996, soda::Baker1995, jalgo::Breslauer1995, stoc::FerraginaG1995, acmcs::Comer1979, soda::FerraginaG1996, esa::FerraginaL1996, cacm::Frenkel1991, tcs::IduryS1994, tcs::IduryS1996, sicomp::KnuthMP1977, focs::Kosaraju1995, sicomp::ManberM1993, jacm::McCreight1976, focs::SahinalpV1996, algor::VitterS1994} } @Article{Hamilton1998, refkey={C1793; PN2735}, title={Usage Counting Analysis for Lazy Functional Languages}, author={G. W. Hamilton}, pages={100--137}, journal=iandcomp, month={1~} # nov, year=1998, volume=146, number=2, abstract={If it can be determined at compile-time how many times values will be used within lazy functional programs, a number of useful optimisations can be performed. For example, call-by-need parameter passing can be converted to call-by-name, and in-place updating and compile-time garbage collection can be performed. In this paper, it is shown how this usage counting information can be obtained by static analysis. This analysis is not itself a major contribution of this paper; similar analyses have been defined before. The major contributions of this paper are that it provides a framework against which this analysis can be proved correct for a lazy functional language, and the analysis is proved to be correct with respect to this framework. The framework for proving the correctness of the analysis is provided by defining a store semantics which counts the number of times values are used.}, references={tcs::Girard1987:1, popl::AriolaFMOW1995:233, lics::GuzmanH1990:333, popl::HudakB1985:300, jlogc::Hughes1992:483, toplas::InoueSY1988:555, popl::Launchbury1993:144} } @Article{NystromJ1998, refkey={C1700; PN2738}, title={A Fully Abstract Semantics for Concurrent Constraint Programming}, author={Sven-Olof Nystr{\"o}m and Bengt Jonsson}, pages={138--180}, journal=iandcomp, month={1~} # nov, year=1998, volume=146, number=2, abstract={A compositional and fully abstract semantics for concurrent constraint programming is developed. It is the first fully abstract semantics which takes into account both non-determinism, infinite computations, and fairness. We present a simple concurrent constraint programming language, whose semantics is given by a set of reduction rules augmented with fairness requirements. In the fully abstract semantics we consider two aspects of a trace, viz.~the function computed by the trace (the functionality) and the set of input and output data (the limit of the trace). We then derive the fully abstract semantics from the set of traces using a closure operation. We give two proofs of full abstraction; the first relies on the use of a syntactically infinite context. The second proof requires only a finite context, but assumes as input a representation of the function to be computed by the context. Finally, we examine the algebraic properties of the programming language with respect to the fully abstract semantics. It turns out that the non-deterministic selection operation can be defined using operations derived from parallel composition and the usual set-theoretic operations on sets of traces.}, references={jacm::AptP1986, ic::BergstraK1984, jacm::BrookesHR1984, lics::Brookes1993, concur::BoerKPR1991, tcs::BoerpP1995, toplas::JagadeesanPP1991, dc::Jonsson1994, iclp::Maher1987, njc::MendlerPSS1995, ipl::Nystrom1996, focs::Russell1989, popl::SaraswatRP1991} } Volume 147, Number 1 November 25, 1998 @Article{Nieuwenhuis1998, refkey={C2012}, title={Decidability and Complexity Analysis by Basic Paramodulation}, author={Robert Nieuwenhuis}, pages={1--21}, journal=iandcomp, month={25~} # nov, year=1998, volume=147, number=1, abstract={It is shown that for sets of Horn clauses saturated under \emph{basic paramodulation}, the word and unifiability problems are in NP, and the number of minimal unifiers is simply exponential (i). For Horn sets saturated wrt.~a special ordering under the more restrictive inference rule of \emph{basic superposition}, the word and unifiability problems are still decidable and unification is finitary (ii). These two results are applied to the following languages. For \emph{shallow} presentations (equations with variables at depth at most one) we show that the closure under paramodulation can be computed in polynomial time. Applying result (i), it follows that shallow unifiability is in NP, which is optimal since unifiability in ground theories is already NP-hard. The shallow word problem is even shown to be polynomial. Generalizing shallow theories to the Horn case, we obtain (two versions of) a language we call \emph{Catalog}, a natural extension of Datalog to include functions and equality. The closure under paramodulation is finite for Catalog sets, hence (i) still applies. For Catalog sets~$S$ the decidability of the full first-order theory of $\mathcal{T}(\mathcal{F})_{=S}$ is shown as well. Finally we define \emph{standard theories}, which include and significantly extend \emph{shallow} theories. Standard presentations can be finitely closed under superposition and result (ii) applies, thus obtaining a new fundamental class with decidable word and unifiability problems and where unification is finitary.}, preliminary={lics::Nieuwenhuis1996}, references={jlogc::BachmairG1994:217, ic::BachmairGLS1995:172, lics::BachmairGW1993:75, ic::ComonHJ1994:154, jsymc::Dershowitz1987:69, lics::Kirchner1986:206, lics::Marche1994:394, lics::NarendranR1993:364, jsymc::NieuwenhuisR1995:321} } @Article{Cabibbo1998, refkey={C1889}, title={The Expressive Power of Stratified Logic Programs with Value Invention}, author={Luca Cabibbo}, preliminary={icdt::Cabibbo1995}, pages={22--56}, journal=iandcomp, month={25~} # nov, year=1998, volume=147, number=1, abstract={The expressive power of the family \textsc{wILOG}$^{(\neg)}$ of relational query languages is investigated. The languages are rule based, with value invention and stratified negation. The semantics for value invention is based on Skolem functor terms. We study a hierarchy of languages based on the number of strata allowed in programs. We first show that, in presence of value invention, the class of stratified programs made of two strata has the expressive power of the whole family, thus expressing the computable queries. We then show that the language \textsc{wILOG}$^{\ne}$ of programs with non-equality and without negation expresses the monotone computable queries, and that the language \textsc{wILOG}$^{1/2, \neg}$ of semipositive programs expresses the semimonotone computable queries.}, references={acmtds::AbiteboulG1991, sigmod::AbiteboulK1989, jcss::AbiteboulV1990, jcss::AbiteboulV1991, pods::AfratiCY1991, popl::AhoU1979, mfcs::Bancilhon1978, jcss::ChandraH1980, pods::ChenW1989, cacm::Codd1970, acmtds::Codd1979, pods::DenninghoffV1993, tkde::GyssensPBG1994, pods::HullS1989, jcss::HullS1993, actai::HullS1994, jlogp::HullS1998, icvldb::HullY1990, pods::HullY1991, ic::Immerman1986, sigmod::KiferKS1992, jacm::KiferLW1995, jcss::KiferW1993, ic::Kolaitis1991, pods::KolaitisV1990, pods::KuperV1984, acmtds::KuperV1993, ipl::Paredaens1978, jacm::BusscheGAG1997, stoc::Vardi1982} } @Article{BenediktGL1998, refkey={C2114}, title={Verifiable Properties of Database Transactions}, author={Michael Benedikt and Timothy Griffin and Leonid Libkin}, pages={57--88}, journal=iandcomp, month={25~} # nov, year=1998, volume=147, number=1, abstract={It is often necessary to ensure that database transactions preserve integrity constraints that specify valid database states. While it is possible to monitor for violations of constraints at run-time, rolling back transactions when violations are detected, it is preferable to verify correctness statically, \emph{before} transactions are executed. This can be accomplished if we can verify transaction safety with respect to a set of constraints by means of calculating \emph{weakest preconditions}. We study properties of weakest preconditions for a number of transaction and specification languages. We show that some simple transactions do not admit weakest preconditions over first-order logic and some of its extensions such as first-order logic with counting and monadic $\Sigma_1^1$. We also show that the class of transactions that admit weakest preconditions over first-order logic cannot be captured by any transaction language. We consider a strong local form of verifiability, and show that it is different from the general form. We define robustly verifiable transactions as those that can be statically analyzed regardless of extensions to the signature of the specification language, and we show that the class of robustly verifiable transactions over first order logic is exactly the class of transactions that admit the local form of verifiability. We discuss the implications of these results for the design of verifiable transaction languages.}, references={jacm::AbiteboulV1989, pods::AbiteboulV1985, jcss::AbiteboulV1990, jcss::AbiteboulV1991, jsyml::AjtaiF1990, actai::Back1981, jacm::BenediktDLW1998, pods::BenediktDLW1996, pods::BenediktGL1996, tcs::BerghammerES1995, icalp::TannenS1991, cacm::Dijkstra1975, jcss::Etessami1997, tcs::Fagin1993, ic::FaginSV1995, tcs::GrumbachT1995, sigmod::HsuI1985, sicomp::Immerman1987, tcs::ImmermanPS1996, acmtds::KarabegV1991, jcss::LibkinW1997, jacm::McCuneH1989, actai::Nicolas1982, jlogc::Nurmonen1996, icde::Qian1990, ipl::Qian1990, actai::Qian1991, acmtds::SheardS1989, apal::Schwentick1996, sigmod::StempleMS1987} } @Article{BshoutyGM1998, refkey={C1926}, title={Noise-Tolerant Parallel Learning of Geometric Concepts}, author={Nader H. Bshouty and Sally A. Goldman and H. David Mathias}, pages={89--110}, journal=iandcomp, month={25~} # nov, year=1998, volume=147, number=1, abstract={We present several efficient parallel algorithms for PAC-learning geometric concepts in a constant-dimensional space. The algorithms are robust even against malicious classification noise of any rate less than $1/2$. We first give an efficient noise-tolerant parallel algorithm to PAC-learn the class of geometric concepts defined by a polynomial number of $(d - 1)$-dimensional hyperplanes against an arbitrary distribution where each hyperplane has a slope from a set of known slopes. We then describe how boosting techniques can be used so that our algorithms' dependence on $\epsilon$ and $\delta$ does not depend on~$d$. Next we give an efficient noise-tolerant parallel algorithm to PAC-learn the class of geometric concepts defined by a polynomial number of $(d - 1)$-dimensional hyperplanes (of unrestricted slopes) against a uniform distribution. We then show how to extend our algorithm to learn this class against any (unknown) product distribution. Next we define a complexity measure of any set~$S$ of $(d - 1)$-dimensional surfaces that we call the \emph{variant} of~$S$ and prove that the class of geometric concepts defined by surfaces of polynomial variant can be efficiently learned in parallel under a product distribution (even under malicious classification noise). Furthermore, we show that the VC-dimension of the class of geometric concepts defined by a single surface of variant one is~$\infty$. Finally, we give an efficient, parallel, noise-tolerant algorithm to PAC-learn any 2-dimensional geometric concept defined by a set~$S$ of 1-dimensional surfaces of polynomial length under a uniform distribution.}, references={focs::AslamD1993:282, colt::AslamD1995:437, colt::Auer1993:253, colt::BalcazarDGW1994:208, jcomp::Baum1990:67, jcss::BergerRS1994:454, jacm::BlumerEHW1989:929, focs::BshoutyCH1994:54, focs::BshoutyC1992:513, colt::Chen1993:243, colt::ChenM1992:16, colt::Decatur1993:262, ic::EhrenfeuchtHKV1989:247, colt::FrazierGMP1994:328, colt::Freund1990:202, colt::Freund1992:391, colt::GoldbergGM1994:198, focs::Haussler1989:40, ic::HausslerKLW1991:129, stoc::Kearns1993:392, colt::LongW1990:273, focs::MaassT1989:262, focs::MaassT1990:203, colt::Sloan1988:91, cacm::Valiant1984:1134, colt::VitterL1988:106, ic::VitterL1992:179} } Volume 147, Number 2 December 15, 1998 @Article{Maneth1998, refkey={C1961}, title={The Generating Power of Total Deterministic Tree Transducers}, author={Sebastian Maneth}, pages={111--144}, journal=iandcomp, month={15~} # dec, year=1998, volume=147, number=2, abstract={Attributed tree transducers are abstract models to study properties of attribute grammars. One abstraction which occurs when modeling attribute grammars by attributed tree transducers is that arbitrary trees over a ranked alphabet are taken as input, instead of derivation trees of a context-free grammar. In this paper we show that with respect to the generating power this is \emph{not} an abstraction, i.e., we show that attributed tree transducers and attribute grammars generate the same class of term (or tree) languages. To prove this, a number of results concerning the generating power of top-down tree transducers are established, which are interesting in their own. We also show that the classes of output languages of attributed tree transducers form a hierarchy with respect to the number of attributes. The latter result is achieved by proving a hierarchy of classes of tree languages generated by context-free hypergraph grammars with respect to their rank.}, references={tcs::CourcelleF1982:163, ic::EngelfrietF1981:125, jcss::EngelfrietH1991:328, actai::EngelfrietH1992:161, tcs::Engelfriet1976:9, mst::Engelfriet1982:95, jcss::EngelfrietRS1980:150, tcs::FulopHVV1993:185, scp::Ganzinger1983:223, actai::Giegerich1988:355, stacs::HabelK1987:207, stacs::HabelK1987:207, mst::Knuth1968:127, mst::Rounds1970:257} } @Article{LautemannSS1998, refkey={C1957}, title={Positive Versions of Polynomial Time}, author={C. Lautemann and T. Schwentick and I. A. Stewart}, pages={145--170}, journal=iandcomp, month={15~} # dec, year=1998, volume=147, number=2, abstract={We show that restricting a number of characterizations of the complexity class~\textbf{P} to be positive (in natural ways) results in the same class of (monotone) problems, which we denote by \textbf{posP}\@. By a well-known result of Razborov, \textbf{posP} is a proper subclass of the class of monotone problems in~\textbf{P}\@. We exhibit complete problems for \textbf{posP} via weak logical reductions, as we do for other logically defined classes of problems. Our work is a continuation of research undertaken by Grigni and Sipser, and subsequently Stewart; indeed, we introduce the notion of a positive deterministic Turing machine and consequently solve a problem posed by Grigni and Sipser.}, references={jacm::AjtaiG1987, sicomp::Borodin1977, jacm::ChandraKS1981, jacm::Cook1971, jcss::Cook1974, lics::Gottlob1995, jcss::GrigniS1995, ic::Immerman1986, sicomp::Immerman1987, sicomp::Immerman1988, jlogc::Stewart1991, jcss::Stewart1992,jlogc::Stewart1994, apal::Stewart1994, ic::Stewart1995, lics::Stolboushkin1995, actai::Szelepcsenyi1988, stoc::Vardi1982} } @Article{BonacinaH1998, refkey={C2079}, title={On the Modelling of Search in Theorem Proving---Towards a Theory of Strategy Analysis}, author={Maria Paola Bonacina and Jieh Hsiang}, pages={171--208}, journal=iandcomp, month={15~} # dec, year=1998, volume=147, number=2, abstract={We present a model for representing search in theorem proving. This model captures the notion of \emph{contraction}, which has been central in some of the recent developments in theorem proving. We outline an approach to measuring the complexity of search which can be applied to analyze and evaluate the behaviour of theorem-proving strategies. Using our framework, we compare contraction-based strategies of different contraction power and show how they affect the evolution of the respective search spaces during the derivation.}, references={jsymc::BachmairD1988, jlogc::BachmairG1994, tcs::BonacinaH1995, jsyml::cookR1979, stacs::Goubault1994, tcs::Haken1985, icalp::HsiangR1987, ic::PlaistedS1996, jsymc::Rusinowitch1991, jacm::Urquhart1987, bsyml::Urquhart1995} } @Article{Ponzio1998, refkey={C1999}, title={The Combinatorics of Effective Resistances and Resistive Inverses}, author={Stephen Ponzio}, pages={209--223}, journal=iandcomp, month={15~} # dec, year=1998, volume=147, number=2, abstract={Let matrix $(\sigma_{ij})$ denote the edge conductances of an electrical network, so that there is a resistor of $r_{ij}=1/\sigma_{ij}$ Ohms between nodes $i$ and~$j$. This uniquely determines the matrix $(R_{ij})$ of \emph{effective resistances}, defined such that if a potential of 1~V is applied across nodes $i$ and $j$, a current of $1/R_{ij}$ will flow. We call $\sigma_{ij}$ the \emph{resistive inverse} of~$(R_{ij})$. One source of interest in the resistive inverse, arising in the design of on-line algorithms, is that it produces an efficient random walk if the walk must pay a cost of $r_{ij}$ for traversing edge $(i,j)$. Coppersmith \emph{et.~al.}\ (1993, \emph{J.~Assoc.\ Comput.\ Mach.}\ \textbf{40}(3), 421--453) show that the random walk that makes transitions according to~$(\sigma_{ij})$ is more efficient---more ``competitive''---than the random walk that makes transitions according to~$(R_{ij})$. \par Coppersmith \emph{et.~al.}\ give a simple but obscure four-step algorithm for computing the resistive inverse. We give a complete self-contained combinatorial explanation of this algorithm, including the classical theorems of Kirchhoff and Foster.}, references={stoc::ChandraRRST1989:574, jacm::CoppersmithDRS1993:421, stoc::Grove1991:260, stoc::KoutsoupiasP1994:507, jalgo::ManasseMS1990:208, soda::Tetali1994:402} } Volume 148, Number 1 January 10, 1999 @Article{AbadiG1999, refkey={C2015}, title={A Calculus for Cryptographic Protocols: The Spi Calculus}, author={Mart{\'\i}n Abadi and Andrew D. Gordon}, pages={1--70}, journal=iandcomp, month={10~} # jan, year=1999, volume=148, number=1, abstract={We introduce the spi calculus, an extension of the pi calculus designed for describing and analyzing cryptographic protocols. We show how to use the spi calculus, particularly for studying authentication protocols. The pi calculus (without extension) suffices for some abstract protocols; the spi calculus enables us to consider cryptographic issues in more detail. We represent protocols as processes in the spi calculus and state their security properties in terms of coarse-grained notions of protocol equivalence.}, references={tacs::Abadi1997, toplas::AbadiBLP1993:706, concur::AbadiG1997:59, esop::AbadiG1998, ieeetse::AbadiN1996:6, tcs::BerryB1992:217, ic::BorealeN1995:279, stoc::BellareR1995:57, IEEETIT::DiffieH1976, tcs::NicolaH1984:83, focs::DolevY1981:350, acmtcs::LampsonABW1992:265, ieeetse::MillenCF1987:274, mscs::Milner1992:119, ic::MilnerPW1992:1, icalp::MilnerS1992:685, cacm::NeedhamS1978:993, mscs::PierceS1996:409, cacm::RivestSA1978:120} } @Article{SalibraG1999, refkey={C1866}, title={A Finite Equational Axiomatization of the Functional Algebras for the Lambda Calculus}, author={Antonino Salibra and Robert Goldblatt}, pages={71--130}, journal=iandcomp, month={10~} # jan, year=1999, volume=148, number=1, abstract={A lambda theory satisfies an equation between contexts, where a context is a $\lambda$-term with some ``holes'' in it, if all the instances of the equation fall within the lambda theory. In the main result of the paper it is shown that the equations (between contexts) valid in every lambda theory have an explicit finite equational axiomatization. The variety of algebras determined by the above equational theory is characterized as the class of isomorphic images of functional lambda abstraction algebras. These are algebras of functions and naturally arise as the ``coordinatizations'' of environment models or lambda models, the natural combinatory models of the lambda calculus. The main result of the paper is also applied to obtain a completeness theorem for the infinitary lambda calculus recently introduced by Berarducci.}, references={mfcs::DiskinB1993, jsyml::Feldman1982, jsyml::Feldman1984, tcs::KennawayKSV1997, ic::Meyer1982, mfcs::PigozziS1993, tcs::PigozziS1995, sicomp::Scott1976} } Volume 148, Number 2 February 1, 1999 @Article{Esik1999, refkey={C2019}, title={Group Axioms for Iteration}, author={Z. {\'E}sik}, pages={131--180}, journal=iandcomp, month={1~} # feb, year=1999, volume=148, number=2, abstract={Iteration theories provide a sound and complete axiomatization of the equational properties of the iteration (or fixed point) operation in many models of theoretical computer science including ordered and metric structures, trees and synchronization trees. All known equational axiomatizations of iteration theories consist of a small set of equational axioms for Conway theories and a complicated equation scheme, the commutative identity. Here we associate an identity with each finite semigroup. We prove that the set consisting of the Conway identities and the group-identities associated with the finite (simple) groups is complete. Moreover, we prove that the Conway identities and a subcollection of the semigroup-identities associated with a subclass of the finite semigroups is complete iff each finite (simple) group divides one of the semigroups in the subclass. We also formulate a conjecture and study its consequences. The results are a generalization of Krob's axiomatization of the equational theory of the regular sets.}, references={sicomp::BloomEW1980:25, sicomp::BloomEW1980:525, mfcs::BloomE1994:52, jcss::ElgotBT1978:362, jcss::Esik1988:66, tcs::Esik1997:217, tcs::EsikL1998:61, jacm::GoguenTWW1977:68, jsyml::HurkensMMMW1998, ic::Kozen1994:366, tcs::Krob1991:207, jcss::Milner1984:439, tcs::Nelson1983:67, tcs::Tiuryn1980:229, lics::Sewell1994, focs::WrightTWG1976:147} } @Article{Ozhigov1999, refkey={C1745}, title={Computations on Nondeterministic Cellular Automata}, author={Yuri Ozhigov}, pages={181--201}, journal=iandcomp, month={1~} # feb, year=1999, volume=148, number=2, abstract={This work concerns the trade-offs between the dimension and the time and space complexity of computations on nondeterministic cellular automata. We assume that the space complexity is the diameter of area in space involved in computation. It is proved that (1)~ever nondeterministic cellular automata (NCA)~$\mathcal{A}$ of dimension~$r$, computing a predicate~$P$ with time complexity~$T(n)$ and space complexity~$S(n)$ can be simulated by $r$-dimensional NCA with time and space complexity $O(T^{1/(r+1)} S^{r/(r+1)})$ and by $r+1$ dimensional NCA with time and space complexity $O(T^{1/2} + S)$, where $T$ and~$S$ are functions constructible in time, (2)~for any predicate~$P$ and integer $r > 1$ if $\mathcal{A}$ is a fastest $r$-dimensional NCA computing~$P$ with time complexity~$T(n)$ and space complexity~$S(n)$, then $T = O(S)$, and (3)~if $T_{r,P}$ is the time complexity of a fastest $r$-dimensional NCA computing predicate~$P$ then \begin{align*} T_{r+1, P} &= O\left( (T_{r,P})^{1 - r/(r+1)^2} \right) \\ T_{r-1, P} &= O\left( (T_{r,P})^{1 + 2/r} \right) \\ \end{align*} Similar problems for deterministic cellular automata (CA) are discussed.}, references={stoc::Cook1971, jcss::Yaku1973} } @Article{MaassR1999, refkey={C2036}, title={On Computations with Pulses}, author={Wolfgang Maass and Berthold Ruf}, pages={202--218}, journal=iandcomp, month={1~} # feb, year=1999, volume=148, number=2, abstract={We explore the computational power of formal models for computation with pulses. Such models are motivated by realistic models for biological neurons and by related new types of VLSI (``pulse stream VLSI'')\@. In preceding work it was shown that the computational power of formal models for computation with pulses is quite high if the pulses arriving at a computational unit have an approximately linearly rising or linearly decreasing initial segment. This property is satisfied by common models for biological neurons. On the other hand, several implementations of pulse stream VLSI employ pulses that are approximately piecewise constant (i.e., step functions). In this article we investigate the relevance of the shape of pulses in formal models for computation with pulses. The results show that the computational power drops significantly if one replaces pulses with linearly rising or decreasing inital segments by piecewise constant pulses. We provide an exact characterization of the latter model in terms of a weak version of a random access machine (RAM)\@. We also compare the language recognition capability of a recurrent version of this model with that of deterministic finite automata and Turing machines.}, references={jacm::LeongS1981} } @Article{Seiden1999, refkey={C1980}, title={Unfair Problems and Randomized Algorithms for Metrical Task Systems}, author={Steve Seiden}, pages={219--240}, journal=iandcomp, month={1~} # feb, year=1999, volume=148, number=2, abstract={Borodin, Linial, and Saks introduced a general model for online systems called \emph{metrical task systems} (1992, \emph{J.~Assoc.\ Comput.\ Mach.}\ \textbf{39}(4), 745--763). In this paper, the unfair two state problem, a natural generalization of the two state metrical task system problem, is studied. A randomized algorithm for this problem is presented, and it is shown that this algorithm is optimal. Using the analysis of unfair two state problem, a proof of a decomposition theorem similar to that of Blum, Karloff, Rabani and Saks (1992, ``Proc.\ 33rd Symposium on Foundations of Computer Science,'' pp.~197--207) is presented. This theorem allows one to design divide and conquer algorithms for specific metrical task systems. Our theorem gives the same bounds asymptotically, but has less restrictive boundary conditions.}, references={focs::Bartal1996:184, stoc::Ben-DavidBKTW1990:379, wads::IraniS1995:159, focs::blumKRS1992, stoc::blumRS1991, jacm::BorodinLS1992, tcs::IraniS1998, algor::KarlinMMO1994, soda::LundR1994, jalgo::ManasseMS1990, cacm::SleatorT1985, jacm::SleatorT1985} } @Article{Spreen1999, refkey={C2216; PN2758}, title={Corrigendum to ``{On} some Decision Problems in Programming''}, author={Dieter Spreen}, pages={241--244}, journal=iandcomp, month={1~} # feb, year=1999, volume=148, number=2, references={ic::Spreen1995} } Volume 149, Number 1 February 25, 1999 @Article{GilleronTT1999, refkey={C1914}, title={Set Constraints and Automata}, author={R{\'e}mi Gilleron and Sophie Tison and Marc Tommasi}, pages={1--41}, journal=iandcomp, month={25~} # feb, year=1999, volume=149, number=1, abstract={We define a new class of automata which is an acceptor model for mappings from the set of terms $T_\Sigma$ over a ranked alphabet $\Sigma$ into a set $E$ of labels. When $E=\{0,1\}^n$ an automaton can be viewed as an acceptor model for $n$-tuples of tree languages. We prove decidability of emptiness and closure properties for this class of automata. As a consequence of these results, we prove decidability of satisfiability of systems of positive and negative set constraints without projection symbols. Moreover we prove that a non-empty set of solutions always contain a regular solution (i.e., a $n$-tuple of regular tree languages). We also deduce decidability results for properties of sets of solutions of systems of set constraints.}, references={ic::AikenKW1995, fplca::AikenM1991, lics::BachmairGW1993, focs::CharatonikP1994, lics::CharatonikP1997, icalp::ChengK1996, icalp::Comon1990, focs::GilleronTT1993, lics::HeintzeJ1990, popl::HeintzeJ1990, popl::JonesM1979, ic::Kozen1998, lics::McAllesterGKW1996} } @Article{Barthe1999, refkey={C1888; PN2751}, title={Order-Sorted Inductive Types}, author={Gilles Barthe}, pages={42--76}, journal=iandcomp, month={25~} # feb, year=1999, volume=149, number=1, abstract={System~$F^\omega_\leq$ is an extension of system~$F^\omega$ with subtyping and bounded quantification. Order-sorted algebra is an extension of many-sorted algebra with overloading and subtyping. We combine both formalisms to obtain~$\mathit{IF}^\omega_\leq$, a higher-order typed $\lambda$-calculus with subtyping, bounded quantification, and order-sorted inductive types, i.e., data types with built-in subtyping and overloading. Moreover we show that $\mathit{IF}^\omega_\leq$ enjoys important meta-theoretic properties, including confluence, strong normalization, subject reduction, and decidability of type checking.}, references={lics::AspinallC1996, njc::DahlOB1998, facs::Dybjer1994, mscs::goguenD1994, pldi::FreemanP1991, tcs::GoguenM1992, jfp::HofmannP1995} } @Article{BorealeNP1999, refkey={C2070; PN2755}, title={Basic Observables for Processes}, author={Michele Boreale and Rocco De Nicola and Rosario Pugliese}, pages={77--98}, journal=iandcomp, month={25~} # feb, year=1999, volume=149, number=1, abstract={A general approach for defining behavioral preorders over process terms as the maximal precongruences induced by basic observables is examined. Three different observables that provide information about the initial communication capabilities of processes and about the possibility that processes get engaged in divergent computations will be considered. We show that the precongruences induced by our basic observables coincide with intuitive and/or widely studied behavioral preorders. In particular, we retrieve in our setting the \emph{must preorder} of De Nicola and Hennessy and the \emph{fair/should preorder} introduced by Cleaveland and Natarajan and by Brinksma, Rensink and Vogler. A new form of testing preorder, which we call \emph{safe-must}, also emerges. The alternative characterizations we offer shed light on the differences between these preorders, and on the role played in their definition by tests for divergence.}, references={actai::Arun-KumarH1992:737, tcs::BoudolCHK1993:31, concur::BrinksmaRV1995:313, jacm::BrookesHR1984:560, jacm::CastellaniH1989:887, actai::Nicola1987:211, tcs::NicolaH1984:83, concur::FournetGLMR1996:406, icalp::MilnerS1992:685, icalp::NatarajanC1995:648, lics::NatarajanC1996:63, actai::OlderogH1986:9, actai::Vogler1989:333, icalp::Yi1991:217, concur::Yi1990:502} } Volume 149, Number 2 March 15, 1999 @Article{Tung1999, refkey={C1702; PN2771}, title={Sentences over Integral Domains and Their Computational Complexities}, author={Shih Ping Tung}, pages={99--133}, journal=iandcomp, month={15~} # mar, year=1999, volume=149, number=2, abstract={Let $R$ be a Hilbertian domain and let $K$ be its fraction field. Let $\psi(x_1, \dots, x_n, y)$ be a quantifier free arithmetical formula over~$R$. We may also take $\psi(x_1, \dots, x_n, y)$ to be an arithmetical formula over $K[x_1, \dots, x_n]$ and write it as $\bar{\psi}(y)$. In this paper we show that if $R$ has enough nonunits and $\forall x_1 \cdots \forall x_n \, \exists y\, \psi(x_1, \dots, x_n, y)$, called an $\forall^n\, \exists$ sentence, is true in~$R$, then $\exists y \, \bar{\psi}(y)$ is true in $K[x_1, \dots, x_n]$. Also, if $R = K[T]$, where $K$ is an infinite integral domain and \[ \forall x_1 \cdots \forall x_n \, \exists y \, \psi(x_1, \dots, x_n, y) \] is true in~$R$, then $\exists y \, \bar{\psi}(y)$ is true in $R[x_1, \dots, x_n]$. These results are applied to find the upper and lower bounds of the time complexities of various decision problems on diophantine equations with parameters and arithmetical sentences. Some of the results are: 1.~The decision problem of $\forall\exists$ sentences and diophantine equations with parameters over the ring of integers of a global field are co-NP-complete. 2.~The decision problem of $\exists\forall$ sentences over the ring of integers of a global field is NP-complete. 3.~Let $K$ be an infinite domain, the time complexities of the decision problems of equations with parameters and $\forall \exists$ sentences over the polynomial ring~$K[t]$ are polynomial time reducible to factoring polynomials over~$K$. 4.~The decision problem of $\forall\exists$ sentences over all algebraic integer rings is in~P\@. 5.~The decision of $\forall\exists$ sentences over all integral domains with characteristic~0 is in~P\@. 6.~The time complexity of the decision problem of $\forall\exists$ sentences over all integral domains is polynomial time reducible to factoring integers over~$Z$ and factoring polynomials over finite fields.}, references={stoc::Cook1971, tcs::Furer1982, jcss::Gathen1985, jcss::GathenK1985, apal::Gradel1989, stoc::Huang1984, ic::Kaltofen1985, jsymc::Kaltofen1985, sicomp::Kaltofen1985, sicomp::Landau1985, jcss::LandauM1985, tcs::Lenstra1984, jcss::Lenstra1985, sicomp::Lenstra1987, jcss::MandersA1978, stoc::ReddyL1978, tcs::Stockmeyer1976, stoc::StockmeyerM1973, jsyml::Tung1987, jalgo::Tung1987, apal::Tung1990, sicomp::Tung1991, ic::Tung1991, ic::Tung1995:315, ic::Tung1995:149, acmtoms::WeinbergerR1976} } @Article{BadouelDR1999, refkey={C1841; PN2752}, title={Context-Free Event Domains Are Recognizable}, author={Eric Badouel and Philippe Darondeau and Jean-Claude Raoult}, pages={134--172}, journal=iandcomp, month={15~} # mar, year=1999, volume=149, number=2, abstract={The possibly non-distributive event domains which arise from Winskel's event structures with binary conflict are known to coincide with the domains of configurations of Stark's trace automata. We prove that whenever the transitive reduction of the order on finite elements in an event domain is a context-free graph in the sense of M\"uller and Schupp, the event domain may also be generated from a finite trace automaton, where both the set of states and the concurrent alphabet are finite. We show that the set of graph grammars which generate event domains is a recursive set. We obtain altogether an effective procedure which decides from an unlabeled graph grammar whether it generates an event domain and which constructs in that case a finite trace automaton recognizing that event domain.}, references={tcs::BaetenBK1987, jacm::BaetenBK1993, ic::BoudolC1994, tcs::Caucal1992, tcs::MullerS1985, tcs::MukundT1992, tcs::Smyth1977} } @Article{RaamsdonkSSX1999, refkey={C1806; PN2750}, title={Perpetual Reductions in {$\lambda$}-Calculus}, author={Femke van Raamsdonk and Paula Severi and Morten Heine B. S{\o}rensen and Hongwei Xi}, pages={173--225}, journal=iandcomp, month={15~} # mar, year=1999, volume=149, number=2, abstract={This paper surveys a part of the theory of $\beta$-reduction in $\lambda$-calculus which might aptly be called \emph{perpetual reductions}. The theory is concerned with \emph{perpetual reduction strategies}, i.e., reduction strategies that compute infinite reduction paths from $\lambda$-terms (when possible), and with \emph{perpetual redexes}, i.e., redexes whose contraction in $\lambda$-terms preserves the possibility (when present) of infinite reduction paths. The survey not only recasts classical theorems in a unified setting, but also offers new results, proofs, and techniques, as well as a number of applications to problems in $\lambda$-calculus and type theory.}, references={ic::BarendregtKKS1987, tcs::BergstraK1979, mscs::CaprettaV1998, tcs::Hindley1989, mfcs::HonsellL1993, jsyml::Howard1980, mfcs::Karr1985} } ------------------------------------------------------------------------ FORTHCOMING The following papers have been assigned definite publication dates, but have not yet appeared in print. All information in this section should be treated as tentative. However, the citekeys below should not change in future revisions of this bibliography. ======================================================================== FUTURE ATTRACTIONS The following manuscripts have been accepted for publication and are currently with the publisher awaiting publication. They are listed here *roughly* in the order in which they are expected to appear in print. @string{ToAppearIC={To appear in \emph{Information and Computation}. Final manuscript received }} ======================================================================== PAPERS RECEIVED FOR PUBLICATION The following manuscripts have recently been received for publication in Information and Computation. @string{Received={Accepted for publication in \emph{Information and Computation}. Final manuscript received for publication }} @Unpublished{KfouryRTU0000, refkey={C1900; PN2756}, title={Alpha-Conversion and Typability}, author={A. J. Kfoury and Ronchi della Rocca, S. and J. Tiuryn and P. Urzyczyn}, journal=iandcomp, note=Received # {April 27, 1998}, references={ic::Leivant1991, lics::Wells1994} } @Unpublished{GuhaK0000, refkey={C2091; PN2754}, title={Improved Methods for Approximating Node Weighted {Steiner} Trees and Connected Dominating Sets}, author={Sudipto Guha and Samir Khuller}, journal=iandcomp, note=Received # {July 22, 1998}, references={jalgo::BermanR1994, ipl::BernP1989, stoc::Feige1996, sicomp::GoemansW1995, algor::GuhaK1998, actai::KouMB1981, jalgo::KleinR1995, jacm::LundY1994, algor::Zelikovsky1993} } @Unpublished{MacielT1000, refkey={C1954}, title={Efficient Threshold Circuits for Power Series}, author={Alexis Maciel and Denis Th{\'e}rien}, journal=iandcomp, note=Received # {August 10, 1998, 1998}, references={sicomp::BeameCH1986, cc::BeigelT1994, cc::GoldmannHR1992, jcss::HajnalMPST1993, ic::MacielT1998, njc::Orponen1994, sicomp::ReifT1992, ieeetit::SiuBKH1993, sidma::SiuR1994, focs::Yao1990:619} } @Unpublished{Yamanishi0000, refkey={C2082; PN2753}, title={Distributed Cooperative {Bayesian} Learning Strategies}, author={Kenji Yamanishi}, journal=iandcomp, note=Received # {June 10, 1998}, references={colt::KearnsS1993, colt::Vovk1990, ieeetit::Yamanishi1998, colt::Yamanishi1996, colt::Yamanishi1997, colt::Yamanishi1998} } @Unpublished{AdlemanH0000, refkey={C2185; PN2761}, title={Function Field Sieve Method for Discrete Logarithms over Finite Fields}, author={Leonard M. Adleman and Ming-Deh A. Huang}, journal=iandcomp, note=Received # {September 9, 1998}, references={focs::Adleman1979:55, IEEETIT::coppersmith1984, ieeetit::DiffieH1976, ieeetit::ElGamal1985, sidma::Gordon1993, stoc::LenstraLMP1990:564, eurocrypt::Odlyzko1984:224, eurocrypt::Odlyzko1984:224} } @Unpublished{CaiC0000, refkey={C2186; PN2762}, title={A Lattice-Based Public-Key Cryptosystem}, author={Jin-Yi Cai and Thomas W. Cusick}, journal=iandcomp, note=Received # {September 9, 1998}, references={stoc::Ajtai1996:99, stoc::AjtaiD1997:284, focs::AroraBSS1993:724, focs::CaiN1997:468, tcs::Cai1998, crypto::GoldreichGH1997:112, sicomp::Lagarias1985:196, tcs::Schnorr1987:201} } @Unpublished{Carlet0000, refkey={C2187; PN2763}, title={On Cryptographic Propagation Criteria for {Boolean} Functions}, author={Claude Carlet}, journal=iandcomp, note=Received # {September 9, 1998}, references={ieeetit::BakerLW1983, crypto::BierbrauerGS1994:247, dcc::BrouwerT1993:95, eurocrypt::CamionC1996:283, crypto::CamionC1996:372, crypto::CamionCCS1991:86, dcc::Carlet1993, eurocrypt::Carlet1997:422, eurocrypt::Carlet1998:462, ieeetit::Carlet1998, ic::Delsarte1973:407, ieeetit::HammonsKCSS1994, fse::JakobsenK1997:28, fse::Knudsen1994:196, eurocrypt::KurosawaS1997, eurocrypt::MeierS1989:549, eurocrypt::PreneelLLGV1990:161, eurocrypt::PreneelGV1991:141, jcrypt::StinsonM1995:167, crypto::WebsterT1985:523, ieeetit::XiaoM1988, dcc::ZhangZ1996:111} } @Unpublished{Dobbertin0000, refkey={C2188; PN2764}, title={Almost Prefect Nonlinear Power Functions on~{$\mathrm{GF}(2^n)$}: The {Niho} Case}, author={Hans Dobbertin}, journal=iandcomp, note=Received # {September 9, 1998}, references={eurocrypt::BethD1993:65, eurocrypt::BethD1993:65, eurocrypt::ChabaudV1994:356, eurocrypt::ChabaudV1994:356, ieeetit::CusickD1996, ieetit::Dobbertin1998, ieeetit::Gold1968, ieeetit::HellesethRS1998, ic::Kasami1971:369, ieeetit::LachaudW1971, eurocrypt::Nyberg1993:55} } @Unpublished{HellesethM0000, refkey={C2189; PN2765}, title={Binary Sequences of Period~{$2^m - 1$} with large Linear Complexity}, author={T. Helleseth and H. M. Martinsen}, journal=iandcomp, note=Received # {September 9, 1998}, references={ieeetit::BoztasK1994, jcrypt::Dai1992:193, eurocrypt::DaiBG1990:189, ieeetit::KumarHC1995} } @Unpublished{HuangX0000, refkey={C2190; PN2766}, title={Some Computational Problems of Cryptographic Significance Concerning Elliptic Curves over Rings}, author={Ming-Deh A. Huang and Chaoping Xing}, journal=iandcomp, note=Received # {September 9, 1998}, references={eurocrypt::Demytko1993:40, eurocrypt::Koyama1995:329, crypto::KoyamaMOV1991:252} } @Unpublished{Johansson0000, refkey={C2191; PN2767}, title={Further Results on Asymmetric Authentication Schemes}, author={Thomas Johansson}, journal=iandcomp, note=Received # {September 9, 1998}, references={eurocrypt::Bierbrauer1995:311, eurocrypt::BrickellS1988:51, crypto::BrickellS1988:564, crypto::ChaumR1990:206, crypto::DesmedtY1990:177, jcrypt::EvenGM1996:35, crypto::Johansson1993:343, ieeetit::Johansson1994, dcc::Johansson1995:205, crypto::Kurosawa1994:140, eurocrypt::KurosawaO1995:289, eurocrypt::Safavi-NainiW1998, crypto::Simmons1984:411, eurocrypt::Simmons1987:151, jcrypt::Simmons1990:77, ieeetit::Smeets1994, eurocrypt::Taylor1994:244, jcrypt::TompaW1988:133} } @Unpublished{KaidaUI0000, refkey={C2192; PN2768}, title={An Algorithm for the {$k$}-Error Linear Complexity of Sequences over {$\mathit{GF}(p^m)$} with Period~{$p^n$}, $p$ a Prime}, author={Takayasu Kaida and Satoshi Uehara and Kyoko Imamura}, journal=iandcomp, note=Received # {September 9, 1998}, references={IEEETIT::Blackburn1994, IEEETIT::DaiI1998, IEEETIT::GamesC1983, IEEETIT::StampM1993} } @Unpublished{Safavi-NainiW0000, refkey={C2193; PN2769}, title={Multireceiver Authentication Codes: Models, Bounds, Constructions and Extensions}, author={R. Safavi-Naini and H. Wang}, journal=iandcomp, note=Received # {September 9, 1998}, references={crypto::FiatN1993:480, crypto::FiatN1993:480, dcc::Quinn1994:177, dcc::Stinson1997:215, jcrypt::DyerFFT1995:189, jcrypt::Stinson1990:23, jcss::WegmanC1981:265, jcss::WegmanC1981:265, crypto::AticiS1996:16, crypto::AticiS1996:16, crypto::BlundoSHKVY1992:471, crypto::BlundoSHKVY1992:471, crypto::Simmons1984:411, eurocrypt::Blom1984:335, eurocrypt::Blom1984:335, dcc::Stinson1994:369, EUROCRYPT::Safavi-NainiW1998:527, IEEETIT::Johanson1994, IEEETIT::Smeets1994} } @Unpublished{GargantiniMM0000, refkey={C1949; PN2779}, title={Dealing with zero-time transitions in axiom systems}, author={Angelo Gargantini and Dino Mandrioli and Angelo Morzenti}, journal=iandcomp, note=Received # {September 18, 1998}, references={ieeetse::BarthomieuD1991, ieeetse::Coen-PorisiniGK1997, ieeetse::FelderMM1994} } @Unpublished{GerthKPP0000, refkey={C1773; PN2778}, title={A Partial Order Approach to Branching Time Logic Model Checking}, author={Rob Gerth and Ruurd Kuiper and Doron Peled and Wojciech Penczek}, journal=iandcomp, note=Received # {September 23, 1998}, references={tcs::BrowneCG1988, toplas::ClarkeES1986, istcs::GerthKPP1995, icalp::GrooteV1990, jacm::HennessyM1985, popl::LichtensteinP1984, lics::NicolaV1990, lics::WillemsW1996} } @Unpublished{Dezani-CiancagliniTU0000, refkey={C2060; PN2773}, title={Discrimination by Parallel Observers: the Algorithm}, author={Mariangiola Dezani-Ciancaglini and Jerzy Tiuryn and Pawe{\l} Urzyczyn}, journal=iandcomp, note=Received # {October 5, 1998}, references={apal::Abramsky1991, ic::AbramskyO1993, ic::BarbaneraDd1995, jsyml::BarendregtCD1983, ic::BorealeN1995, ic::Boudol1994, ic::boudolL1996, ic::CoppoDZ1987, mscs::DamianiDG1999, tcs::Dezani-CiancaglinidP1996, sicomp::Dezani-CiancaglinidP1998, tcs::Dezani-CiancagliniM1986, lics::Dezani-CiancagliniTU1997, ic::Hennessy1994, ic::GrooteV1992, tcs::Levy1976, apal::Longo1983, ic::MilnerPW1992:1, ic::MilnerPW1992:41, tcs::MilnerPW1993, icalp::Ong1992, lics::Ong1993, tcs::Plotkin1993, concur::Sangiorgi1993, ic::Sangiorgi1994, icalp::Scott1982} } @Unpublished{JakobyRS0000, refkey={C1974; PN2776}, title={Malign Distributions for Average Case Circuit Complexity}, author={Andreas Jakoby and R{\"u}diger Reischuk and Christian Schindelhauer}, journal=iandcomp, note=Received # {October 5, 1998}, references={jcss::Ben-DavidCGL1992, swat::Grape1990, jcss::Gurevich1991, stoc::JakobyRS1994, icalp::JakobyRSW1994, stacs::JakobyS1996, sicomp::Levin1986, ipl::LiV1992, sctc::Miltersen1991, sicomp::Miltersen1993, cc::ReischukS1996, sctc::WangB1992} } @Unpublished{BlumK0000, refkey={C1987; PN2772}, title={Greibach Normal Form Transformation, Revisited}, author={Norbert Blum and Robert Koch}, journal=iandcomp, note=Received # {October 5, 1998}, references={ic::EhrenfeuchtR1984, jacm::Greibach1965, mfcs:Piricka-Kelemenova1975, tcs::Kelemenova1984, stacs::KochB1997, jack::Rosenkrantz1967, tcs::Urbanek1985} } @Unpublished{GuoNW0000, refkey={C2166}, title={Complexity of Nilpotent Unification and Matching Problems}, author={Qing Guo and Paliath Narendran and D. A. Wolfram}, journal=iandcomp, note=Received # {September 8, 1998}, references={jacm::Baader1993, lics::ComonHJ1992, tcs::Goldfarb1981, lics::Kirchner1986, toplas::MartelliM1982, lics::NarendranPS1993, stoc::Schaefer1978} } @Unpublished{GiunchigliaS0000, refkey={C2167}, title={Building Decision Procedures for Modal Logics from Propositional Decision Procedures---the Case Study of Modal~{K(m)}}, author={Fausto Giunchiglia and Roberto Sebastiani}, journal=iandcomp, note=Received # {September 15, 1998}, references={acmcs::Bryant1992, jacm::DavisLL1962, jlogc::DAgostinoM1994} } @Unpublished{RousselM0000, refkey={C2170}, title={The Achievement of Knowledge Bases by Cycle Search}, author={Olivier Roussel and Philippe Mathieu}, journal=iandcomp, note=Received # {September 23, 1998}, references={tcs::MathieuD1994} } @Unpublished{Luz0000, refkey={C2173}, title={Using Tableaux to Automate the {Lambek} and other Categorial Calculi}, author={Saturnino F Luz}, journal=iandcomp, note=Received # {September 9, 1998}, references={jlogc::DAgostinoM1994} } @Unpublished{GiacomoM0000, refkey={C2172}, title={Combining Deduction and Model Checking into Tableaux and Algorithms for {Converse-PDL}}, author={Giuseppe De Giacomo and Fabio Massacci}, journal=iandcomp, note=Received # {September 22, 1998}, references={lics::BhatCG1995, jcss::FisherL1979, sicomp::Ladner1977, stoc::Pratt1987, focs::Pratt1979, jcss::Pratt1980, tcs::StirlingW1991, ic::StreettE1989, jcss::VardiW1986, ic::VardiW1994} } @Unpublished{HERMANNK0000, refkey={C2175}, title={Unification Algorithms Cannot Be Combined in Polynomial Time}, author={Miki Hermann and Phokion G. Kolaitis}, journal=iandcomp, note=Received # {September 15, 1998}, references={jsymc::BoudetJS1989, jsymc::Boudet1993, jsymc::BaaderS1996, stoc::Cook1971, jsymc::Fages1987, tcs::FagesH1986, jsymc::HermannK1995, mfcs::HermannK1995, sicomp::KannanB1979, jsymc::KirchnerR1994, jsymc::MartinN1989, jsymc::Nipkow1991, ic::Ringeissen1996, jsymc::Schmidt-Schauss1989, jacm::Stickel1981, focs::Toda1989, tcs::Valiant1979, sicomp::Valiant1979, jsymc::Yelick1987} } @Unpublished{DenzingerS0000, refkey={C2178}, title={Automatic Acquisition of Search Control Knowledge from Multiple Proof Attempts}, author={J{\"o}rg Denzinger and Stephan Schulz}, journal=iandcomp, note=Received # {October 2, 1998}, references={jsymc::DenzingerS1996, icalp::HsiangR1987, jacm::Huet1980} } @Unpublished{BasinM0000, refkey={C2179}, title={Structuring Metatheory on Inductive Definitions}, author={David Basin and Se{\'a}n Matthews}, journal=iandcomp, note=Received # {September 22, 1998}, references={popl::Macqueen1986, popl::MitchellP1985} } @Unpublished{KolbeW0000, refkey={C2180}, title={On Terminating Lemma Speculations}, author={Thomas Kolbe and Christoph Walther}, journal=iandcomp, note=Received # {October 5, 1998}, references={jsymc::Dershowitz1987, cacm::DershowitzM1979, acmcs:Ellman1989} } @Unpublished{KestenPSY0000, refkey={C1860; PN2774}, title={Decidable Integration Graphs}, author={Y. Kesten and A. Pnueli and J. Sifakis and S. Yovine}, journal=iandcomp, note=Received # {October 16, 1998}, references={tcs::AlurCHHHNOSY1995, tcs::AlurD1994, ic::AlurH1993, lics::AsarinCM1997, tcs::AsarinMP1995, ic::burchCMDH1992, lics::BouajjaniES1993:147, toplas::ClarkeES1986, ipl::ChaochenHR1991:269, jcss::HenzingerKPV1998, icalp::HenzingerMP1992, actai::NicollinSY1993, jacm::Papadimitriou1981} } @Unpublished{HomeierM0000, refkey={C2176}, title={Secure Mechanical Verification of Mutually Recursive Procedures}, author={Peter V. Homeier and David F. Martin}, journal=iandcomp, note=Received # {October 12, 1998}, references={sicomp::Cook1978, toplas::GriesL1980, actai::IgarashiLL1975, icalp::MoriconiS1981, scp::Sokolowski1984, tcs::Stoughton1988} } @Unpublished{MoserM0000, refkey={C1828; PN2770}, title={Byzantine-Resistant Total Ordering Algorithms}, author={Louise E. Moser and P. M. Melliar-Smith}, journal=iandcomp, note=Received # {October 29, 1998}, preliminary={wads::MoserM1995}, references={ic::Bar-NoyDGK1991, dc::Bar-NoyD1991, wads::BazziN1992, podc::Ben-Or1993, ic::Bracha1987, jacm::BrachaT1985, jacm:ChandraT1996, jacm::ChandraHT1996, podc::choklerHD1998, cacm::Cristian1991, jacm::FischerLP1985, wads::GarayP1992, wads::gopalT1989, cacm::Lamport1978, sicomp::MoserMA1993, cacm::MoserMABL1996, jacm::PeaseSL1980, focs::Rabin1983, acmtcs::Schneider1984:145, sicomp::touegPS1987, cacm::RenesseBM1996} } @Unpublished{BorodinE0000, refkey={C2008; PN2775}, title={On Randomization in Online Computation}, author={Allan Borodin and Ran El-Yaniv}, journal=iandcomp, note=Received # {November 2, 1998}, references={focs::BeameBRRT1990, algor::Ben-DavidBKTW1994, jacm::BorodinLS1992, stoc::CoppersmithDRS1990, sidma::ChrobakKPV1991, jalgo::FiatKLMSY1991, focs::Yao1977} } @Unpublished{GrumbachM0000, refkey={C1991; PN2777}, title={An Algebra for Pomsets}, author={St{\'e}phane Grumbach and Tova Milo}, journal=iandcomp, note=Received # {November 25, 1998}, preliminary={icdt::GrumbachM1995}, references={vldbj::AbiteboulB1995, icvldb::AbiteboulCM1993, acmtds::AbiteboulG1991, sigmod::AbiteboulK1989, icvldb::Albert1991, stoc::AbiteboulV1991, icdt::BeeriK1990, pods::BeeriM1992, pods::BusscheP1991, icalp::TannenS1991, jcss::ChandraH1980, focs::CannyR1987, pods::ColbyRSG1994, icvldb::Agarwal+1996, pods::GrumbachM1993, apal::GurevichS1986, focs::Gurevich1983, icdt::GrumbachV1990, pods::GrumbachV1991,pods::GinsburgW1992, pods::HullS1988, pods::HullS1989, jacm::HopcroftT1974, stoc::HopcroftW1974, ic::Immerman1986, jacm::Jacobs1982, pods::KuperV1984, pods::LibkinW1994, icvldb::Mumick+1990, icvldb::Richardson1992, stoc::Vardi1982} } @Unpublished{CaseJLZ0000, refkey={C2072}, title={Incremental Concept Learning for Bounded Data Mining}, author={John Case and Sanjay Jain and Steffen Lange and Thomas Zeugmann}, journal=iandcomp, note=Received # {November 6, 1998}, references={jcss::Angluin1980, ic::Angluin1980, tcs::ArikawaSY1992, jacm::blum1967, ic::blumB1975, mst::Case1974, colt::Case1988, sicomp::Case1998, tcs::CaseS1983, stacs::File1988, ic::FreivaldsS1993, jcss::FulkJO1994, ic::gold1967, icalp::JiangSSY1993, jcss::LangeZ1996, mst::LangeZ1996, colt::Wright1989, ic::ZeugmannLK1995} } @Unpublished{BaligaCJ0000, refkey={C2121}, title={The Synthesis of Language Learners}, author={Ganesh Baliga and John Case and Sanjay Jain}, journal=iandcomp, note=Received # {June 25, 1998}, references={colt::Ambainis1996, jcss::Angluin1980, ic::Angluin1980, jacm::Angluin1982, tcs::ArikawaSY1992, icalp::BaligaC1993, jcss::BaligaCJ1995, colt::BaligaCJ1996, ic::BlumB1975, jacm::Blum1967, mst::Case1974, sicomp::Case1998, icalp::CaseL1982, tcs::CaseS1983, colt::Daley1988, colt::DaleyKV1992, colt::DaleyPVW1991, colt::JonghK1996, ic::Fulk1990, focs::Fulk1990, ic::Gold1967, stacs::KapurB1992, ic::KinberZ1991, colt::LangeZ1992, colt::LangeZ1993, jlogp::MuggletonR1994, ic::OshersonSW1988, ic::OshersonW1982, jacm::Pitt1989, ic::PittS1988, jsyml::Rogers1958, jsyml::Shapiro1971, cacm::Valiant1984, tcs::WiehagenFK1984, colt::Wright1989, ic::ZeugmannLK1995} } @Unpublished{Ehrhard0000, refkey={C1918}, title={A Relative {PCF}-Definability Result for Strongly Stable Functions and Some Corollaries}, author={Thomas Ehrhard}, journal=iandcomp, note=Received # {November 30, 1998}, references={tcs::BucciarelliE1993, ic::BucciarelliE1994, ic::CartwrightCF1994, lics::colsonE1994, mscs::Ehrhard1993, apal::Ehrhard1996, tcs::Girard1986, ic:Meyer1982, tcs::Milner1977, tcs::Plotkin1977} } @Unpublished{Zhang0000, refkey={C2120}, title={Automata, {Boolean} Matrices, and Ultimate Periodicity}, author={Guo-Qiang Zhang}, journal=iandcomp, note=Received # {November 30, 1998}, references={ic::Abe1995, mscs::bloomE1993, ic::Kozen1994, tcs::Krob1991, jacm::Salomaa1966, tcs::SeiferasM1976, ic::StearnsH1963} } @Unpublished{Engelfriet0000, refkey={C1922}, title={Derivation Trees of Ground Term Rewriting Systems}, author={Joost Engelfriet}, journal=iandcomp, note=Received # {June 24, 1998}, references={ic::Brainerd1969, lics::DauchetT1990, icalp::Dershowitz1981, ic::DauchetHL1990, ipl::FrazierP1994, tcs::Oyamaguchi1987, tcs::VAgvolgyi1993} } @Unpublished{SakaiTM0000, refkey={C1831}, title={Proper Learning Algorithm for Functions of {$k$} Terms under Smooth Distributions}, author={Yoshifumi Sakai and Eiji Takimoto and Akira Maruoka}, journal=iandcomp, note=Received # {November 30, 1998}, references={focs::Bshouty1993, colt::BlumS1990:144, colt::FlamminiMK1992, stoc::KearnsLPV1987, ic::KuceraMP1994, jacm::PittV1988, cacm::Valiant1984} } @Unpublished{Fleischer0000, refkey={C2014}, title={Decision Trees: Old and New Results}, author={Rudolf Fleischer}, journal=iandcomp, note=Received # {June 29, 1998}, references={stoc::Ben-Or1983, stoc::BjornerLY1992, jcss::DobkinL1979, jacm::FusseneggerG1979, ipl::Gasarch1991, stoc::GrigorievKHS1996, mfcs::Jaromczyk1981, jam::ManberT1985, focs::MansourST1988, jacm::Heide1984, tcs::Heide1985, cc::MontanaPR1994, jacm::Mora85, ipl::ODunling1988, jcss::Rabin1972, ipl::Ramanan1987, jacm::Reingold1972, sicomp::RivestY1980, tcs::Snir1982, jalgo::SteeleY1982, sicomp::Strassen1983, algor::Yao1989, focs::Yao1992:268} } @Unpublished{GurevichV0000, refkey={C2038}, title={Logic with Equality: Partisan Corroboration, and Shifted Pairing}, author={Yuri Gurevich and Margus Veanes}, journal=iandcomp, note=Received # {February 24, 1999}, references={icalp::CortierGJV1999, lics::DegtyarevV1996, tcs::DegtyarevV1996, tcs::DegtyarevGNVV1999, lics::DegtyarevMV1996, lics::GallierNPS1988, ic::GallierNPS1990, lics::GallierRS1987, tcs::Goldfarb1981, lics::Goubault1994, icalp::GurevichV1997, lics::Veanes1998, lics::Voronkov1998, tcs::Voronkov1998} } @Unpublished{AfekMT0000, refkey={C1920}, title={The Power of Multi-Objects}, author={Yehuda Afek and Michael Merritt and Gadi Taubenfeld}, journal=iandcomp, note=Received # {March 1, 1999}, references={jacm::AfekADGMS1993, podc::AttiyaD1996, jacm::AfekGMT1995, podc::AfekGMT1992, podc::AndersonM1995, podc::AfekMTT1997, dc::Anderson1993, dc::Anderson1994, podc::AfekS1994, podc::AfekWW1993, jacm::FischerLP1985, toplas::Herlihy1991, toplas::HerlihyW1990, podc::IsraeliR1994, podc::Jayanti1993, wdag::JayantiK1997, dc::Lamport1986:77, dc::Lamport1986:86, podc::LynchT1987, wdag::MerrittT1991, podc::ruppert1998, podc::ShavitT1995} } @Unpublished{LathropL0000, refkey={C1993}, title={Recursive Computational Depth}, author={James I. Lathrop and Jack H. Lutz}, journal=iandcomp, note=Received # {January 29, 1999}, references={jacm::Chaitin1975, icalp::FennerLM1995, tcs::JuedesLL1994, tcs::JuedesL1995, sicomp::Lutz1990, jcss::Lutz1992, ic::Martin-Lof1966, mst::Schnorr1971, jcss::Schnorr1973, ic::Solomonoff1964} } @Unpublished{AwerbuchBRS0000, refkey={C1969}, title={Piecemeal Graph Exploration by a Mobile Robot}, author={Baruch Awerbuch and Margrit Betke and Ronald L. Rivest and Mona Singh}, journal=iandcomp, note=Received # {July 27, 1998}, references={sicomp::AwerbuchBCP1998, focs::AwerbuchG1985, ieeetit::AwerbuchG1987, jalgo::Bar-EliBFY1994, focs::BenderS1994, focs::BlumC1993, sicomp::blumRS1997, jacm::DengKP1998, focs::DengP1990, focs::Kleinberg1994, tcs::PapadimitriouY1991, ic::RivestS1993} } @Unpublished{StolboushkinT0000, refkey={C1805}, title={Finite Queries Do Not Have Effective Syntax}, author={Alexei P. Stolboushkin and Michael A. Taitslin}, journal=iandcomp, note=Received # {February 18, 1999}, preliminary={pods::StolboushkinT1995}, references={lics::AvronH1991, cacm::Codd1970, jacm::Paola1969, pods::KanellakisKR1990, acmtods::GelderT1991, ipl::Vardi1981} } @Unpublished{Ranzato0000, refkey={C2253}, title={Closures on {CPOs} Form Complete Lattices}, author={Francesco Ranzato}, journal=iandcomp, note=Received # {April 20, 1999}, references={lics::AbramskyM1999, toplas::CortesiFGPR1997, acmcs::Cousot1996, popl::cousotC1977, popl::cousotC1979, ic::FalaschiGMP1997, acmcs::FileGR1996, tcs::GermanoM1991, scp::GiacobazziR1998, ic::GiacobazziR1998, mfcs::GiacobazziRS1998, toplas::Jensen1997, icalp::MycroftN1983} } @Unpublished{CleavelandDSY0000, refkey={C2030}, title={Testing Preorders for Probabilistic Processes}, author={Rance Cleaveland and Zeynep Dayar and Scott A. Smolka and Shoji Yuen}, journal=iandcomp, note=Received # {April 22, 1999}, preliminary={icalp::CleavelandSZ1992, concur::YuenCDS1994}, references={icalp::CleavelandSZ1992:708, lics::CleavelandZ1991:110, tcs::NicolaH1984:83, ic::GlabbeekSS1995:59, concur::JouS1990:367, lics::JonssonY1995:431, ic::LarsenS1991:1, podc::LynchT1987:137, concur::NunezFL1995:249, concur::NunezFL1995:249, concur::Segala1996:299, tcs::WuSS1997:1, concur::YuenCDS1994:497} } @Unpublished{BartalCL0000, refkey={C2197}, title={A Randomized Algorithm for Two Servers on the Line}, author={Yair Bartal and Marek Chrobak and Lawrence L. Larmore}, journal=iandcomp, note=Received # {April 27, 1999}, references={esa::AchlioptasCN1996, ipl::AlbersSW1995, stoc::BartalBBT1997, focs::BlumKRS1992, sidma::ChrobakKPV1991, sicomp::ChrobakL1991, ipl::ChrobakLLR1997, wads::IraniS1995, algor::KarlinMMO1994, stoc::KoutsoupiasP1994, jacm::KoutsoupiasP1995, ipl::KoutsoupiaP1996, sidma::LundR1994, jalgo::ManasseMS1990, algor::McGeochS1991} } @Unpublished{MaassS0000, refkey={C2064}, title={On the Complexity of Learning for Spiking Neurons with Temporal Coding}, author={Wolfgang Maass and Michael Schmitt}, journal=iandcomp, note=Received # {April 26, 1999}, references={jacm::blumerEHW1989, ic::Haussler1992, jcss::HoffgenSH1995, jacm::KearnsLV1994, jcss::KoiranS1997, stoc::MacintyreS1993, cacm::Valiant1984} } @Unpublished{GrecoS0000, refkey={C2061}, title={Complexity and Expressive Power of Deterministic Semantics for {DATALOG}}, author={Sergio Greco and Domenico Sacc{\`a}}, journal=iandcomp, note=Received # {February 8, 1999}, references={pods::AbiteboulSV1990, icalp::BuccafurriGS1997, ic::BlassG1982, jcss::ChandraH1982, ic::ChenT1995, tods::EiterGM1997, jlogp::Fitting1985, icdt::GrecoSZ1995, lics::Kolaitis1990, jcss::KolaitisP1991, icalp::LaenensVZ1992, jacm::MarekT1991, jcss::papadimitriouY1982, ipl::Sacca1996, jcss::Sacca1997, pods::SaccaZ1990, jlogc::SaccaZ1997, pods::Schlipf1990, jcss::Gelder1992, jacm::GelderRS1991, stoc::Vardi1982} } @Unpublished{HirstL0000, refkey={C2033}, title={Alternation and Bounded Concurrency are Reverse Equivalent}, author={Tirza Hirst and Moshe Lewenstein}, journal=iandcomp, note=Received # {August 3, 1998}, references={jacm::ChandraKS1981, jacm::DrusinskyH1994, tcs::GlobermanH1996, scp::Harel1987, concur::HarelKV1997, lics::HarelRV1990, jacm::HirstH1994, cacm::Hoare1978, focs::MeyerF1971, focs::Kozen1976} } @Unpublished{BernasconiE0000, refkey={C2051}, title={Hilbert Function and Complexity Lower Boudns for Symmetric {Boolean} Functions}, author={Anna Bernasconi and Lavinia Egidi}, journal=iandcomp, note=Received # {December 4, 1998}, references={focs::AlonKV1996, sctc::Beigel1993, mst::KrauseW1995, stoc::Smolensky1987, focs::Smolensky1993} } @Unpublished{DrosteG0000, refkey={C2232}, title={The {Kleene-Sch\"utzenberger} Theorem for Formal Power Series in Partially Commuting Variables}, author={Manfred Droste and Paul Gastin}, journal=iandcomp, note=Received # {January 21, 1999}, references={tcs::AalbersbergR1988, tcs::Droste1995, icalp::DrosteG1997, ic::Schutzenberger1961} } @Unpublished{AlurMP0000, refkey={C2211}, title={Model-Checking of Correctness Conditions for Concurrent Objects}, author={Rajeev Alur and Ken McMillan and Doron Peled}, journal=iandcomp, note=Received # {May 11, 1999}, preliminary={lics::AlurMP1996}, references={mst::AalbersbergH1989, cacm::EswaranGLT1976, tcs::FleR1985, toplas::HerlihyW1990} } @Unpublished{GarrigueR0000, refkey={C2269}, title={Semi-Explicit First-Class Polymorphism for~{ML}}, author={Jacques Garrigue and Didier R\'emy}, journal=iandcomp, note=Received # {May 6, 1999}, preliminary={tacs::GarrigueR1997}, references={icfplca::AikenW1993, popl::DamasM1982, oopsla::EifrigST1995, toplas::LauferO1994, ic::OderskyL1996, popl::PierceT1998, , tacs::Remy1994, popl::RemyV1997, lics::Wells1994, ic::WrightF1994} } @Unpublished{Ohori0000, refkey={C2270}, title={Type-Directed Specialization of Polymorphism}, author={Atsushi Ohori}, journal=iandcomp, note=Received # {May 6, 1999}, preliminary={TACS::Ohori1997}, references={tcs::Alimohamed1995, tacs::BirkedalH1997, ic::Breazu-TannenCGS1991, tods::BunemanO1996, acmcs::CardelliW1985, icfp::CraryWM1998, popl::DamasM1982, toplas::HarperM1993, popl::HarperM1993, popl::HarperM1995, esop::Jones1992, tacs::Jones1994, tacs::Kahn1987, pldi::TarditiMCSHL1996} } @Unpublished{BirkedalH0000, refkey={C2267}, title={Relational Interpretations of Recursive Types in an Operational Setting}, author={Lars Birkedal and Robert Harper}, journal=iandcomp, note=Received # {May 6, 1999}, preliminary={TACS::BirkedalH1997}, references={jfp::HarperDM1993, ic::MasonST1995, ic::Pitts1996, tcs::Plotkin1975, tcs::Plotkin1977, pldi::Reppy1991, icalp::Reynolds1974, icalp::Scott1982, icfp::ShaoLM1998, ic::Statman1985, pldi::TarditiMCSHL1996} } @Unpublished{BruceCP0000, refkey={C2268}, title={Comparing Object Encodings}, author={Kim B. Bruce and Luca Cardelli and Benjamin C. Pierce}, journal=iandcomp, note=Received # {May 6, 1999}, preliminary={tacs::BruceCP1997}, references={toplas::AmadioC1993, ecoop::AbadiC1995, popl::AbadiCV1996, ecoop::BruceFP1997, ieeetse::BlacmHJLC1987, jfp::Bruce1994, ecoop::BruceSG1995, ic::Cardeli1988, popl::CookHC1990, mscs::CurienG1992, jfp::CardelliL1991, oopsla::CookP1989, acmcs::CardelliW1985, oopsla::DayGLM1995, tacs::FisherM1994, tcs::Ghelli1995, jfp::HofmannP1995, ecoop::Jacobs1996, popl::Mitchell1990, popl::MinamideMH1996, toplas::MitchellP1988, popl::MitchellP1985, ic::Pierce1994, tcs::PierceS1997:235, jfp::PierceT1993, mscs::Reichel1995:129} } @Unpublished{BonsangueK0000, refkey={C2266}, title={Towards an Infinitary Logic of Domains: Abramsky Logic for Transition Systems}, author={Marcello M. Bonsangue and Joost N. Kok}, journal=iandcomp, note=Received # {May 6, 1999}, preliminary={tacs::BonsangueK1997}, references={apal::Abramsky1991, ic::Abramsky1991, tcs::BonsangueJK1995, entcs::Bonsangue1997, ic::BakkerZ1982, jacm::HennessyM1985, icalp::Scott1982, icalp::Smyth1983} } @Unpublished{Comon0000, refkey={C2250}, title={Sequentiality, Monadic Second-Order Logic and Tree Automata}, author={Hubert Comon}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::Comon1995}, references={stacs::BogaertT1992, ic::ComonD1994, lics::DauchertHLT1988, lics::DauchetT1990, apal::Kennaway1989, jsymc::KlopM1991, sicomp::Oyamaguchi1993, sicomp::Seidl1990, lics::SekarR1990, mst::ThatcherW1968, lics::Toyama1992} } @Unpublished{DowekHK0000, refkey={C2249}, title={Higher Order Unification via Explicit Substitutions}, author={Gilles Dowek and Th{\'e}r{\`e}se Hardin and Claude Kirchner}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::DowekHK1995}, references={jfp::AbadiCCL1991, jsyml::Andrews1971, jsyml::Church1940, jacm::CurienHL1996, tcs::Dauchet1992, tcs::Dougherty1993, jlogc::Dowek1993, lics::DowekHK1995, tcs::Goldfarb1981, icalp::HintermeierKK1994, ic::Huet1973, tcs::Huet1975, toplas::MartelliM1982, jsymc::Miller1992, jsymc::SnyderG1989} } @Unpublished{Walukiewicz0000, refkey={C2248}, title={Completeness of {Kozen's} Axiomatisation of the Propositional {$\mu$}-Calculus}, author={Igo Walukiewicz}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::Walukiewicz1995}, references={jcss::HarelKP1982, mfcs::JaninW1995, concur::Kaivola1995, tcs::Kozen1983, tcs::NiwinskiW1996:99, tcs::StirlingW1991, ic::StreettE1989, lics::Walukiewicz1993} } @Unpublished{EtessamiI0000, refkey={C2247}, title={Tree Canonization and Transitive Closure}, author={Kousha Etessami and Neil Immerman}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::EtessamiI1995}, references={focs::AleliunasKLLR1979, jcss::BarringtonIS1990, sicomp::CookR1980, mfcs::DublishM1990, tcs::EtessamiI1995, sctc::Etessami1995, jcss::Immerman1982, sicomp::Immerman1987, sicomp::Immerman1988, sicomp::Immerman1989, stoc::Lindell1992, jsyml::Otto1996, jcss::Ruzzo1980} } @Unpublished{Kopylov0000, refkey={C2246}, title={Decidability of Linear Affine Logic}, author={A. P. Kopylov}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::Kopylov1995}, references={tcs::Girard1987, lics::Kanovich1992, tacs::Kanovich1994, focs::LincolnMSS1990} } @Unpublished{DoughertyS0000, refkey={C2245}, title={Equality between Functionals in the Presence of Coproducts}, author={Daniel J. Dougherty and Ramesh Subrahmanyam}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::DoughertyS1995}, references={icalp::CosmoK1993, cacm::DershowitzM1979, jacm::Huet1980, jsyml::Statman1982} } @Unpublished{Pfenning0000, refkey={C2244}, title={Structural Cut Elimination~{I}: Intuitionistic and Classical Logic}, author={Frank Pfenning}, journal=iandcomp, note=Received # {March 1, 1999}, preliminary={lics::Pfenning1995}, references={tcs::Abramsky1993, lics::Breazu-TannenKP1993, tcs::Gallier1993, tcs::Girard1987, apal::Girard1993, jacm::HarperHP1993, lics::Miller1994, apal::MillerNPS1991, lics::Nipkow1991} } @Unpublished{0000, refkey={}, title={}, author={}, journal=iandcomp, note=Received # {, 1999}, references={} } ========================================================================