Identifying state coding conflicts in asynchronous system specifications using Petri net unfoldings

Abstract

State coding conflict detection is a fundamental part of synthesis of asynchronous concurrent systems from their specifications as Signal Transition Graphs (STGs), which are a special kind of labelled Petri nets. The paper develops a method for identifying state coding conflicts in STGs that is intended to work within a new synthesis framework based on Petri net unfolding. The latter offers potential advantages due to a partial order representation of highly concurrent behaviour as opposed to the more traditional construction of a state graph, known to suffer from combinatorial explosion. We develop a necessary condition for coding conflicts to exist, by using an approximate state covering approach. Being computationally easy, yet conservative, such a solution may produce fake conflicts. A technique for refining the latter, with extra computational cost, is provided. p b+ a-region of p Cube for p: C(p)= 1-a+ Marked Detection of fake conflicts Refinement of approximations C(p1) & C(p2) = ? Event-based properties State-based STG implementability properties Persistency Boundedness Consistency State coding conflicts Marked regions for places Approximation by cubes Check conflicts by cubes We are here Verification land STG unfolding Verification