Concurrency for graph grammars
in a Petri net shell

Graph grammars are a powerful model of concurrent and distributed systems which can be seen as a proper extension of Petri nets. Inspired by this correspondence we develop truly concurrent semantics for DPO graph grammars based on (deterministic) processes and on a Winskel's style unfolding construction, and we show that the two approaches can be reconciled. A basic role is played by the study of contextual and inhibitor nets, two extensions of ordinary nets which can be seen as intermediate models between graph grammars and ordinary Petri nets.