Non-Atomic Transition Firing in Contextual Nets

Chatain, T; Haar, S; Koutny, M; Schwoon, S

doi:10.1007/978-3-319-19488-2_6

Non-Atomic Transition Firing in Contextual Nets

Lookup NU author(s): Professor Maciej Koutny ORCiD

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Abstract

The ring rule for Petri nets assumes instantaneous and simultaneousconsumption and creation of tokens. In the context of ordinaryPetri nets, this poses no particular problem because of the system'sasynchronicity, even if token creation occurs later than token consumptionin the ring. With read arcs, the situation changes, and several differentchoices of semantics are possible. The step semantics introduced byJanicki and Koutny can be seen as imposing a two-phase ring scheme:rst, the presence of the required tokens is checked, then consumptionand production of tokens happens. Pursuing this approach further, wedevelop a more general framework based on explicitly splitting the phasesof ring, allowing to synthesize coherent steps. This turns out to denea more general non-atomic semantics, which has important potential forsafety as it allows to detect errors that were missed by the previous semantics.Then we study the characterization of partial-order processesfeasible under one or the other semantics.