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Pomsets with Boxes: Protection, Separation, and Locality in Concurrent Kleene Algebra

Authors Paul Brunet , David Pym

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  • 16 pages

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Author Details

Paul Brunet
  • University College London, UK
David Pym
  • University College London, UK


The authors are grateful to their colleagues at UCL and within IRIS project for their interest. We also thank the anonymous referees for their comments and suggestions.

Cite AsGet BibTex

Paul Brunet and David Pym. Pomsets with Boxes: Protection, Separation, and Locality in Concurrent Kleene Algebra. In 5th International Conference on Formal Structures for Computation and Deduction (FSCD 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 167, pp. 8:1-8:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2020)


Concurrent Kleene Algebra is an elegant tool for equational reasoning about concurrent programs. An important feature of concurrent programs that is missing from CKA is the ability to restrict legal interleavings. To remedy this we extend the standard model of CKA, namely pomsets, with a new feature, called boxes, which can specify that part of the system is protected from outside interference. We study the algebraic properties of this new model. Another drawback of CKA is that the language used for expressing properties of programs is the same as that which is used to express programs themselves. This is often too restrictive for practical purposes. We provide a logic, "pomset logic", that is an assertion language for specifying such properties, and which is interpreted on pomsets with boxes. In contrast with other approaches, this logic is not state-based, but rather characterizes the runtime behaviour of a program. We develop the basic metatheory for the relationship between pomset logic and CKA, including frame rules to support local reasoning, and illustrate this relationship with simple examples.

Subject Classification

ACM Subject Classification
  • Theory of computation → Logic and verification
  • Theory of computation → Semantics and reasoning
  • Theory of computation → Separation logic
  • Concurrent Kleene Algebra
  • Pomsets
  • Atomicity
  • Semantics
  • Separation
  • Local reasoning
  • Bunched logic
  • Frame rules


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