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Oxford has long been one of the main centres of concurrency research. The theory of concurrency is the study of how multiple, independently controlled threads of behaviour behave when running together and interacting with each other. We develop and analyse models of concurrency and their operational, denotational and other semantics, always with practical applications in mind. Historically, most of the work on concurrency at Oxford has centred on CSP (Communicating Sequential Processes). CSP is one of the original process algebras - mathematical notations for describing the patterns of communication and interaction between agents that interact via explicit (usually handshaken) message passing. CSP now has a rich mathematical theory and has been used in a wide range of applications, which have in turn been facilitated by the availability of a number of automated tools.

Current work on concurrency includes a number of topics related to computer security, techniques to help overcome the state explosion problem, and various efforts linking work on CSP to work in other formalisms.

Our key achievements include Roscoe's solution to the problem of modelling in CSP beyond possible divergence, the publication of Walker's book on the pi-calculus, and a $295K research grant from the US ONR on interoperability that led to the discovery of new models of concurrency fully abstract with respect to responsiveness.

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