A
Petri net (also known as a
place/transition net or
P/T net) is one of several
mathematical modeling languages for the description of
distributed systems. A Petri net is a directed
bipartite graph, in which the nodes represent transitions (i.e. events that may occur, signified by bars) and places (i.e. conditions, signified by circles). The directed arcs describe which places are pre- and/or postconditions for which transitions (signified by arrows). Some sources state that Petri nets were invented in August 1939 by
Carl Adam Petri — at the age of 13 — for the purpose of describing chemical processes.