Discrete-event simulation

In discrete event simulation, only the points in time at which the state of the system changes are represented. In other words, the system is modelled as a series of events, i.e. instants in time when a state-change occurs. Examples of events are "a customer arrives", "a customer starts receiving service" and "a machine is repaired". Each of these occurs at an instant in time.

A number of mechanisms have been proposed for carrying out discrete event simulation, amonth them are the event-based, activity-based, process-based and three-phase approaches. The three-phase approach is is used by a number of commercial simulation software packages, but from the user's point of view, the specifics of the underlying simulation method are generally hidden.

(from Simulation - The practice of model development and use by Stewart Robinson, Wiley 2004) --RTE 15:29, 11 July 2006 (UTC)