Petri nets

A formal, graphical, executable technique for the specification and analysis of concurrent, discrete-event dynamic systems; a technique undergoing standardisation. More on Petri nets...

Discrete event dynamic system

a system which may change state over time, based on current state and state-transition rules, and where each state is separated from its neighbour by a step rather than a continuum of intermediate infinitesimal states. Often falling into this classification are information systems, operating systems, networking protocols, banking systems, business processes and telecommunications systems.