An Event Structure Semantics for Graph Grammars with Parallel Productions

We propose a truly concurrent semantics for graph grammars, based on event structures, that generalizes to arbitrary consuming grammars (i.e., such that each production deletes some items) the semantics presented in [4] for the subclass of safe grammars. Also, parallel derivations are explicitly considered, instead of sequential ones only as in [4]. The “domain” and the “event structure” of a grammar are introduced independently, and one main result shows that they are strongly related, since the domain is the domain of finite configurations of the event structure. Another important result provides an abstract characterization of when two (parallel) graph derivations should be considered as equivalent from a true-concurrency perspective.