In 2004 I wrote with Ole Jensen a comprehensive technical report Bigraphs and mobile processes (revised). It describes a topographical model of distributed agents that can manipulate their own linkages and (nested) locations. It aims to model both man-made and natural systems, and draws inspiration from the pi calculus and the calculus of mobile ambients. The main technical advance is to generalise the behavioural theory of both these calculi.
Here are the slides for a lecture course on bigraphs. I gave it first in April 2005 at the Chinese Academy of Sciences, Beijing.
A shorter paper Transitions, link graphs and Petri nets , written with Jamey Leifer, concentrated upon link graphs which are essentially what is left of bigraphs when nesting of locations is forgotten. Link graphs are adequate to deliver a simple behavioural theory for condition/event Petri nets, as the paper explains.
A third paper, Axioms for bigraphical structure, axiomatises the static structure of bigraphs (i.e. their structural congruence).
In September 2004 I wrote a short report called Bigraphs whose names have multiple locality . This is a smooth generalisation of the binding bigraphs introduced in the comprehensive technical report; I hope it will ease the presentation of some dynamical systems (such as the lambda calculus) within the bigraphical framework.
Early in 2005 I wrote Pure bigraphs: structure and dynamics, which presents pure bigraphs alone (i.e. without binding). This simple version of the theory is seen to be rich enough to recover exactly the strong bisimilarity of finite CCS.
Here is a fuller listing of my recent papers (with co-authors) on bigraphs, indicating how they relate to each other.
In 1997 I wrote a paper called Turing, computing and communication for a celebration of the 60th anniversary of Alan Turing's paper on the entscheidungsproblem. I tried to identify elements of interaction in the sense that Turing identified elements of computation.
In June 2003 I gave a keynote lecture entitled Computing in space to the annual Conference on Computer-aided Radiology and Surgery. The message of the lecture was that the advent of pervasive computing, in medicine as elsewhere, creates not only great opportunities but also a great demand for rigour in the design and validation of distributed software.
In January 2003 I wrote a short essay called What's in a name?, to be published in a volume of papers written in honour of Roger Needham. It relates to his well-known paper on "Naming", which highlights the notion of a pure name. The paper explains what the pi-calculus allows you to do with pure names. It also considers whether these are all the things you should be able to do with them. As an illustration I use an example on directory lookup from Needham's paper.
At the IFIP World Computer Congress in Toulouse, August 2004, I gave a plenary lecture A scientific horizon for computing . I repeated it, slightly modified, at the Chinese Academy of Sciences at Beijing in April 2005. After an account of the UK Grand Challenges Exercise, I discussed one of the six current Grand Challenge proposals. Its theme is the "Global Ubiquitous Computer"; it aims to develop scalable engineering design principles, in close harmony with scientific concepts and theories to specify and analyse the designs.