Marked graph

A marked graph is a Petri net in which every place has exactly one incoming arc, and exactly one outgoing arc. This means, that there can not be conflict, but there can be concurrency. Mathematically: . Marked graphs are used mostly to mathematically represent concurrently running operations, such as a multiprocessor machine's internal process state. This class of Petri nets gets the name from a popular way of representing them: as a graph where each place is an edge and each transition is a node.