A Classification of Models for Concurrency

The difference between the models may be expressed in terms of the parameters according to which models are often classified. For instance, a distinction made explicitly in the theory of Petri nets, but sensible in a wider context, is that between so-called “system” models allowing an explicit representation of the (possibly repeating) states in a system, and “behaviour” models abstracting away from such information, which focus instead on the behaviour in terms of patterns of occurrences of actions over time. Prime examples of the first type are transition systems and Petri nets, and of the second type, trees, event structures and traces. Thus, we can distinguish among models according to whether they