Petri Nets and Reliable Real-Time Systems

The zero-test problem is a well-known limitation of Petri nets, and unfortunately it appears very frequently when reliable real-time systems are concerned. If the Petri net is bounded (it is generally the case when actual systems are specified), the zero-test problem can be solved by the introduction of complementary places. Nevertheless this solution presents three major drawbacks: the specification becomes little readable,the net can rarely be reduced,the information given by the linear invariants does not take into account the elementary loops and therefore the zero-tests.