ABSTRACT
In a separate chapter, models for discrete-event systems (DES) were introduced and discussed. To briefly recap, the behavior of such systems is governed by discrete events occurring asynchronously over time and solely responsible for generating state transitions. In between event occurrences, the state of such systems is unaffected. Examples include computer and communication networks, automated manufacturing systems, air traffic control systems, command-control systems, advanced monitoring and control systems in automobiles or large buildings, intelligent transportation systems, distributed software systems, and so forth. DES are also referred to as event-driven systems to distinguish them from time-driven systems. In the latter, the state of the system generally changes as time changes: with every “tick” of an underlying clock the state is expected to change and differential (or difference) equations are the standard modeling framework one uses in such cases. In contrast, in an event-driven system state transitions are the result of combining asynchronous concurrent event processes. Modeling frameworks for DES include state automata and Petri nets, discussed elsewhere in the book.
