Execution Strategies for Petri Net Simulations

Petri Nets can provide the means for modeling and analyzing asynchronous and concurrent operations. In some applications, such as the modeling and analysis of information processing and decision making organizations where different decisionmakers may use different protocols to perform their tasks, it is often necessary to use simulation to study the dynamic behavior of the system. However, when implementing a simulation system on a digital computer capable of handling large scale nets with complex protocols, the automation of the firing process poses problems because a computer executes instructions sequentially. A simulation system based on Predicate Transition nets has been designed which has imbedded in it as choices a number of rules for handling concurrency, confusion, and token colors. These rules may represent either the actual protocols, or ways of handling some model implementation problems. Several examples illustrate the effect of different rules on the execution of the net and on the final markings. Sponsored in part by NSF-SES84-190885. Prepared in cooperation with Meta Software Corp., Cambridge, MA.