Introduction to the Modelling, Control and Optimization of Discrete Event Systems

Abstract

The theory of Discrete Event Systems (DES) is a research area of current vitality. The development of this theory is largely stimulated by discovering general principles which are (or are hoped to be) useful to a wide range of application domains. In particular, technological and/or ‘man-made’ manufacturing systems, communication networks, transportation systems, and logistic systems, all fall within the class of DES. There are two key features that characterize these systems. First, their dynamics are event-driven as opposed to time-driven, i.e., the behavior of a DES is governed only by occurrences of different types of events over time rather than by ticks of a clock. Unlike conventional time-driven systems, the fact that time evolves in between event occurrences has no visible effect on the system. Second, at least some of the natural variables required to describe a DES are discrete. Examples of events include the pushing of a button or an unpredictable computer failure. Examples of discrete variables involved in modelling a DES are descriptors of the state of a resource (e.g., UP, DOWN, BUSY, IDLE) or (integer-valued) counters for the number of users waiting to be served by a resource. Some authors use the acronym DEDS, for a discrete event dynamic system, rather than DES, to emphasize the fact that the behavior of such systems can, and usually will, change as time proceeds.