Petri Nets

Abstract

Petri nets and finite state machine (FSM) automata lack the full modeling and decision power that can be implemented with microprocessor based digital computers, which have the complete expressiveness of the Turing machine In terms of formal languages, Petri net languages include all regular languages, but not all context-sensitive (or even context-free) languages [Peterson, 1981]. Specifics regarding these details are discussed in section 2.5.1. It is logical to then ask why Petri nets are such a popular modeling paradigm for discrete event systems when they lack the full expressiveness of the Turing machine. A degree of modeling power is sacrificed in order to take advantage of the simple and direct graphical representation of Petri nets and, more importantly, the elegant and efficient mathematical representation that makes them easy to code and invites the use of many well known mathematical analytical tools. These reasons combined with the fact that many practical systems can be effectively modeled with PN languages make the Petri net an excellent choice for many DES modeling and control tasks.