In: Sangiorgi, D.; de Simone, R.: Lecture Notes in Computer Science, Vol. 1466: Proceedings 9th International Conference on Concurrency Theory (CONCUR'98), Nice, France, September 1998, pages 501-516. Springer-Verlag, 1998.
Abstract: Petri nets with read arcs are investigated with respect to their unfolding, where read arcs model reading without consuming, which is often more adequate than the destructive read-and-rewrite modeled with loops in ordinary nets. The paper redefines the concepts of a branching process and unfolding for nets with read arcs and proves that the set of reachable markings of a net is completely represented by its unfolding. The specific feature of branching processes of nets with read arcs is that the notion of a co-set is no longer based on the binary concurrency relation between the elements of the unfolding, contrary to ordinary nets. It is shown that the existing conditions that finite prefix construction can only be applied to a subset of nets with read arcs, the co called read-persistent nets. Although this class is restrictive, it is sufficiently practical due to its conformance to the notion of hazard-freedom in logic circuits. The latter appears to be one of the most promising applications of nets with read arcs.
Keywords: Petri nets, asynchronous systems, branching processes, concurrency semantics, net unfolding, read arcs.