Discrete Event Modelling and Simulation
By: Hans Vangheluwe
For a class of formalisms labelled discrete-event, system models are described at an abstraction level where the time base is continuous, but during a bounded time-span, only a finite number of relevant events occurs. These events can cause the state of the system to change. In between events, the state of the system does not change. This is unlike continuous models in which the state of the system may change continuously over time.
Discrete-event formalisms are clearly at a high level of abstraction. This abstraction is often appropriate for realistic representation of a system's behaviour. Furthermore, as in between events, the state of the system does not change, a discrete-event simulator need not explicitly represent the state of the system at non-event times. This allows for highly efficient simulation as compared to continuous simulation, where in principle, state information must be represented at each point in continuous time.
Link to material: http://www.cs.mcgill.ca/~hv/classes/MS/discreteEvent.pdf