Modelling systems with dynamic priorities

In this paper we discuss concurrent systems with dynamic priorities, i.e. we allow the priority relation to change as the system evolves. We identify two classes of such systems, state-controlled and event-controlled priority systems. We define their nonsequential semantics (in terms of step sequences) which reflects both the priority constraints and concurrency specification. It is then shown that for a given prioritised system it is possible to construct an equivalent non-prioritised one. The systems dealt with in this paper are safe Petri nets augmented with a priority specification.