TRANSITION-SYSTEMS, EVENT STRUCTURES, AND UNFOLDINGS

A subclass of transition systems called elementary transition systems can be identified with the help of axioms based on a structural notion called regions. Elementary transition systems have been shown to be t he transition system model of a basic system model of net theory calle d elementary net systems. Here we show that by smoothly strengthening the regional axioms for elementary transition systems, one obtains a s ubclass called occurrence transition system. We then prove that occurr ence transition systems are the transition system model of yet another basic model of concurrency, namely, prime event structures. We then p ropose an operation of unfolding elementary transition systems into oc currence transition systems, We prove that it is ''correct'' in a stro ng categorical sense. (C) 1995 Academic Press, Inc.