A Clustering Approach to Approximate the Timed Reachability Graph for a Class of Time Petri Nets.

Timed extended reachability graphs (TERG) of time Petri nets abstract the temporal specifications and represent the feasible trajectories under the earliest firing policy. One drawback of such graphs is the rapid increase in the number of states with respect to time specifications. For this reason, approximations of TERG that remove some states have been studied in recent works. In this article, we improve the approximation of a TERG. New objects—called vertices—are defined to manipulate the time constraints and algorithms are proposed to cluster nearby vertices. A metric based on the time constraints is defined for this purpose and a cluster TERG of reduced size is obtained. [ABSTRACT FROM AUTHOR]