On Liveness Enforcement of DSSP net systems

Deterministically Synchronized Sequential Process (DSSP) are modular Petri Net (PN) systems composed by a set of state machines PNs (called also agents) cooperating in a distributed way through asynchronous message passing. Messages can delay the normal execution of agents, but to not addition the resolution of conflicts. The modular structure of DSSP allows strong analytical results, (for example, the rank theorem provides necessary and sufficient condition for structural liveness). This paper considers a synthesis problem of liveness enforcing. For some particular structures of DSSP in which the rank theorem does not hold we provide a technique based on the pre-assignment of the buffers in order to ensure that the model becomes live.