Congruence from the operator’s point of view: Syntactic requirements on modal characterizations

Maciej Gazda, Wan Fokkink*, Vittorio Massaro

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


A basic sanity property of a process semantics is that it constitutes a congruence with respect to standard process operators. This issue has been traditionally addressed by developing, for a specific process semantics, a syntactic format for operational semantics specifications. We suggest a novel, orthogonal approach, which focuses on a specific process operator and determines a class of congruence relations for this operator. To this end, we impose syntactic restrictions on Hennessy–Milner logic, so that a process semantics whose modal characterization satisfies those criteria is guaranteed to be a congruence with respect to the operator in question. We investigate alternative composition, action prefix, projection, encapsulation, renaming, and parallel composition with communication, in the context of both concrete and weak process semantics.

Original languageEnglish
Pages (from-to)329-351
Number of pages23
JournalActa Informatica
Issue number3-5
Early online date2 Dec 2019
Publication statusPublished - 1 Oct 2020


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