Petri-Net and Augmented-Petri-Net

A Petri-net is an abstract, formal model of information flow. The properties, concepts, and techniques of Petri-nets are developed in a search for natural, simple and powerful methods for describing and analyzing the flow of information and control in systems, particularly systems that may exhibit asynchronous and concurrent activities. The major use of Petri-nets has been the modelling of systems of events in which it is possible for some events to occur concurrently but there are constraints on the concurrence, precedence or frequency of these occurrences.

(sound bite)