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Classes are Monday-Wednesday, 10:30-12noon, 320 Soda
Office hours: Mondays, 2-3pm, or by appointment
References: the main reference for the course will be
lecture notes. New
lecture notes will be distributed after each lecture. Meanwhile, you
can also
refer to older notes
About this course: Computational Complexity theory looks
at the computational resources (time, memory, communication, ...)
needed
to solve computational problems that we care about, and it is
especially
concerned with the distinction between "tractable" problems, that we
can
solve with reasonable amount of resources, and "intractable" problems,
that are beyond the power of existing, or conceivable, computers. It
also
looks at the trade-offs and relationships between different "modes" of
computation (what if we use randomness, what if we are happy with
approximate,
rather than exact, solutions, what if we are happy with a program that
works only for most possible inputs, rather than being universally
correct,
and so on).
This course will roughly be divided into two parts: we will
start with "basic" and "classical" material about time, space, P versus
NP, polynomial hierarchy and so on, including moderately modern
and
advanced material, such as the power
of randomized algorithm, the complexity of counting problems, the
average-case
complexity of problems, and interactive protocols. In the second part,
we will focus on more research oriented material, to be chosen among
PCP and
hardness of approximation; circuit, proof complexity, and communication
lower
bounds; and derandomization, average-case complexity and
extractors.
For reasons that are
only partially understood, a disproportionate number of the most
beautiful
results in Complexity theory in the 80s and 90s have been found by
Berkeley
graduate students. After taking this course, you will hopefully feel
upon
you the mission of continuing this tradition into the new decade.
Lecture 9 (9/29) Valiant-Vazirani (same notes as
last lecture)
Lecture 10 (10/4) #P and approximate counting [notes]
Lecture 11 (10/6) #P and approximate counting (same
notes as last lecture)
(see these notes on
probability if you had difficulty following today's proofs)