Extensional Petri net

Petri nets form a concurrent model for distributed and asynchronous systems. They are capable of modeling information flow in a closed system, but are generally not suitable for the study of compositionality. We address the issue of Petri net compositionality by introducing extensional Petri nets. In an extensional Petri net some places are external while others are internal. Every external place is labeled by a distinguished interface name. When composing two extensional Petri nets two places with a same label are coerced. An external place can be turned into an internal place by applying localization operator. The paper takes a look at bisimulation semantics and observational properties of the extensional Petri nets.