ABSTRACT
Historically, scientists and engineers have concentrated on studying and harnessing natural phenomena which are modeled by the laws of gravity, classical and nonclassical mechanics, physical chemistry, etc. In so doing, one typically deals with quantities such as the displacement, velocity, and acceleration of particles and rigid bodies, or the pressure, temperature, and flow rates of fluids and gases. These are continuous variables in the sense that they can take on any value as time itself continuously evolves. Based on this fact, a vast body of mathematical tools and techniques has been developed to model, analyze, and control these time-driven systems around us. But in the day-to-day life of our technological and increasingly computerdependent world, we notice two things: First, many of the quantities we deal with are discrete; and second, what drives many of the processes we use and depend on are instantaneous “events” such as pushing a button, or hitting a keyboard key. In fact, much of the technology we have invented and rely on is event-driven: Communication networks, manufacturing facilities, or the execution of a computer program are typical examples. This has motivated the development of a theory for Discrete Event Systems (DES) [8], mostly during the 1980s, leading to new modeling frame-
works, analysis techniques, design tools, testing methods, and systematic control and optimization procedures for this new generation of event-driven systems.
