On the relationship of CCS and CSP

  • Stephen D. Brookes
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 154)


This paper compares two models of concurrency, Milner's Calculus of Communicating Systems (CCS) and the failures model of Communicating Sequential Processes (CSP) developed by Hoare, Brookes and Roscoe. By adapting Milner's synchronisation trees to serve as notation for both CCS and CSP, we are able to define a representation mapping for CSP processes. We define an equivalence relation on synchronisation trees which corresponds precisely to the notion of failure equivalence. Milner's calculus is founded on a different notion, observation equivalence. We show how these two equivalences are related. Just as Milner's equivalence can be characterised as the smallest relation satisfying a set of axioms, we find a suitable set of axioms for the failures equivalence relation. This again makes explicit the differences between the two systems, as well as revealing that the semantic models underlying CCS and CSP are comparable.


Normal Form Proof System Parallel Composition Visible Action Communicate Sequential Process 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1983

Authors and Affiliations

  • Stephen D. Brookes
    • 1
  1. 1.Department of Computer ScienceCarnegie-Mellon UniversityPittsburgh

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