Conflict vs Causality in Event Structures

Daniele Gorla
(Dip. Informatica, Sapienza Univ. di Roma)
Ivano Salvo
(Dip. Informatica, Sapienza Univ. di Roma)
Adolfo Piperno
(Dip. Informatica, Sapienza Univ. di Roma)

Event structures are one of the best known models for concurrency. Many variants of the basic model and many possible notions of equivalence for them have been devised in the literature. In this paper, we study how the spectrum of equivalences for Labelled Prime Event Structures built by Van Glabbeek and Goltz changes if we consider two simplified notions of event structures: the first is obtained by removing the causality relation (Coherence Spaces) and the second by removing the conflict relation (Elementary Event Structures). As expected, in both cases the spectrum turns out to be simplified, since some notions of equivalence coincide in the simplified settings; actually, we prove that removing causality simplifies the spectrum considerably more than removing conflict. Furthermore, while the labeling of events and their cardinality play no role when removing causality, both the labeling function and the cardinality of the event set dramatically influence the spectrum of equivalences in the conflict-free setting.

In Jorge A. Pérez and Jurriaan Rot: Proceedings Combined 26th International Workshop on Expressiveness in Concurrency and 16th Workshop on Structural Operational Semantics (EXPRESS/SOS 2019), Amsterdam, The Netherlands, 26th August 2019, Electronic Proceedings in Theoretical Computer Science 300, pp. 86–101.
Published: 22nd August 2019.

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