I. Introduction
Petri nets are able to model, simulate and analyze discrete event dynamic systems with concurrency, asynchrony, uncertainty, and randomness. A stochastic Petri Net (SPN) is an extension of the Petri Net [1]–[3], where the time delay of transition is a random variable. And it can be used for system modeling and performance analysis. Traditional SPN performance indicators (such as the average number of tokens and transition utilization ratio) are obtained by processes including generating the reachable graph, solving the state equation, etc. However, this method is not always practical since it relies on the premise that the state equation has a unique solution, i.e., the state transition matrix is full rank. It is a challenge to analyze system performance when the state equation has no unique solution.