Process Semantics of P/T-Nets with Inhibitor Arcs

In this paper, we define a process semantics of P/T-nets with inhibitor arcs (PTI-nets). For PTI-nets with bounded inhibiting places, we combine the existing approaches for ordinary P/T-nets and for elementary net systems with inhibitor arcs. To deal with unbounded inhibiting places, a new feature has to be added to the underlying occurrence nets. In either case we show how to construct a process from a step sequence and give a complete characterization of all processes which can be obtained in this way. Using these processes it is possible to express the causal relationships between events in a PTI-net behaviour.