Basic qualitative properties of Petri nets with multi-guarded transitions

In many discrete event dynamic systems, there exist tasks that can start performing before every input data is available. A common device exhibiting such a feature is the multiplexer: its output can be produced as soon as data is available in the selected channel without waiting for data in the other channels. The Petri net formalism can be easily extended to model this behavior by allowing a transition have several guards. Under this extension, a transition can fire as soon as the guard selected for the next firing is satisfied, what usually enhances the system performance with respect to the conventional ldquomono-guardedrdquo system. This paper explores how some fundamental qualitative properties are preserved or lost when a conventional system is transformed to a system with several guards. The main properties studied are reachability, boundedness, and liveness.