,
Valentina Castiglioni
,
Anna Ingólfsdóttir
,
Bas Luttik
Creative Commons Attribution 4.0 International license
In this paper we investigate the equational theory of (the restriction, relabelling, and recursion free fragment of) CCS modulo rooted branching bisimilarity, which is a classic, bisimulation-based notion of equivalence that abstracts from internal computational steps in process behaviour. Firstly, we show that CCS is not finitely based modulo the considered congruence. As a key step of independent interest in the proof of that negative result, we prove that each CCS process has a unique parallel decomposition into indecomposable processes modulo branching bisimilarity. As a second main contribution, we show that, when the set of actions is finite, rooted branching bisimilarity has a finite equational basis over CCS enriched with the left merge and communication merge operators from ACP.
@InProceedings{aceto_et_al:LIPIcs.CONCUR.2022.6,
author = {Aceto, Luca and Castiglioni, Valentina and Ing\'{o}lfsd\'{o}ttir, Anna and Luttik, Bas},
title = {{On the Axiomatisation of Branching Bisimulation Congruence over CCS}},
booktitle = {33rd International Conference on Concurrency Theory (CONCUR 2022)},
pages = {6:1--6:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-246-4},
ISSN = {1868-8969},
year = {2022},
volume = {243},
editor = {Klin, Bartek and Lasota, S{\l}awomir and Muscholl, Anca},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2022.6},
URN = {urn:nbn:de:0030-drops-170692},
doi = {10.4230/LIPIcs.CONCUR.2022.6},
annote = {Keywords: Equational basis, Weak semantics, CCS, Parallel composition}
}