ABSTRACT
Petri nets were the topic of Carl Adam Petri’s Ph.D. dissertation in 1963; today they are the accepted model for protocols and event-driven applications.
7.1 Definition and Notation Petri nets are a special form of directed graph: a bipartite directed graph. (A bipartite graph has two sets of nodes, V1 and V2, and a set of edges E, with the restriction that every edge has its initial node on one of the sets V1 , V2, and its terminal node in the other set.) In a Petri net, one of the sets is referred to as “places,” and the other is referred to as “transitions.” These sets are usually denoted as P and T, respectively. Places are inputs to and outputs of transitions; the input and output relationships are functions, and they are usually denoted as In and Out, as in the following definition.
Definition
