On determining the AND-OR hierarchy in workflow nets

This paper presents a notion of reduction where a WF net is transformed into a smaller net by iteratively contracting certain well-formed subnets into single nodes until no more of such contractions are possible. This reduction can reveal the hierarchical structure of a WF net, and since it preserves certain semantic properties such as soundness, can help with analysing and understanding why a WF net is sound or not. The reduction can also be used to verify if a WF net is an AND-OR net. This class of WF nets was introduced in earlier work, and arguably describes nets that follow good hierarchical design principles. It is shown that the reduction is confluent up to isomorphism, which means that despite the inherent non-determinism that comes from the choice of subnets that are contracted, the final result of the reduction is always the same up to the choice of the identity of the nodes. Based on this result, a polynomial-time algorithm is presented that computes this unique result of the reduction. Finally, it is shown how this algorithm can be used to verify if a WF net is an AND-OR net

General Refinement for High Level Petri Nets: in Proceedings of the 17th Conference on the Foundations of Software Technology and Theoretical Computer Science

The algebra of M-nets, a high level class of labelled Petri nets, was introduced in the Petri Box Calculus in order to cope with the size problem of the low level nets, especially if applied as semantical domain for parallel programming languages. A general, unrestricted refinement operator intended to represent the procedure call mechanism for concurrent calls is introduced into the M-net calculus. Its coherence with the low level refinements is exhibited, together with its main properties.SCOPUS: cp.kinfo:eu-repo/semantics/publishe