On time-average limits in deterministic and stochastic petri nets

In this poster paper, we study performance of systems modeled by deterministic and stochastic Petri nets (DSPN). As a performance measure, we consider long-run average time spent in a set of markings. Even though this measure often appears in DSPN literature, its existence has never been considered. We provide a DSPN model of a simple communication protocol in which the long-run average time spent in a fixed marking is not well-defined due to a highly unstable behavior of the model. Further, we introduce a syntactical restriction on DSPN which preserves most of the modeling power yet guarantees existence of the long-run average.