Unique Solutions of Contractions, CCS, and their HOL Formalisation

Chun Tian
(Fondazione Bruno Kessler, Italy)
Davide Sangiorgi
(Università di Bologna and INRIA, Italy)

The unique solution of contractions is a proof technique for bisimilarity that overcomes certain syntactic constraints of Milner's "unique solution of equations" technique. The paper presents an overview of a rather comprehensive formalisation of the core of the theory of CCS in the HOL theorem prover (HOL4), with a focus towards the theory of unique solutions of contractions. (The formalisation consists of about 20,000 lines of proof scripts in Standard ML.) Some refinements of the theory itself are obtained. In particular we remove the constraints on summation, which must be weakly-guarded, by moving to rooted contraction, that is, the coarsest precongruence contained in the contraction preorder.

In Jorge A. Pérez and Simone Tini: Proceedings Combined 25th International Workshop on Expressiveness in Concurrency and 15th Workshop on Structural Operational Semantics (EXPRESS/SOS 2018), Beijing, China, September 3, 2018, Electronic Proceedings in Theoretical Computer Science 276, pp. 122–139.
Published: 24th August 2018.

ArXived at: http://dx.doi.org/10.4204/EPTCS.276.10 bibtex PDF
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