Software-Based Synthesis of Maximally Permissive Liveness Enforcing Supervisory Policies for a Class of General Petri Nets

A Petri net (PN) N(m(0)) is live if all of its transitions are potentially fireable from every reachable marking. A PN that is not live can be made live by a liveness enforcing supervisory policy (LESP), which decides the set of transitions that are to be permitted at any given marking, such that the supervised-PN is live. We assume there are uncontrollable transitions that cannot be prevented by the LESP. An LESP is said to be maximally permissive, if the fact that it prevents the firing of a transition at a given marking, is sufficient to conclude that all other LESPs would prevent the firing of the same transition at the marking. If there is an LESP for a PN, there is a unique maximally permissive LESP. This paper is about the synthesis of the maximally permissive LESP for a class of PN models with the help of software tools. The paper concludes with a description of ongoing software development activities.