A Canonical Contraction for Safe Petri Nets

Abstract

Abstract. Under maximal semantics, the occurrence of an event a in a concurrent run of an occurrence net may imply the occurrence of other events, not causally related to a, in the same run. In recent works, we have formalized this phenomenon as the reveals relation, and used it to obtain a contraction of sets of events called facets in the context of occurrence nets. Here, we extend this idea to propose a canonical contraction of general safe Petri nets into pieces of partial-order behaviour which can be seen as "macro-transitions" since all their events must occur together in maximal semantics. On occurrence nets, our construction coincides with the facets abstraction. Our contraction preserves the maximal semantics in the sense that the maximal processes of the contracted net are in bijection with those of the original net.