Fairness, Simulations, and Inhibitor Arcs

An execution of a parallel system is fair if no activity that is capable of taking place is denied this capability for a very long time, or even forever. Depending on how this somewhat diffuse notion is formalised, different types of fairness can be distiguished, ranging from very strong notions of fairness to really weak ones. Several types of fairness properties will be examined. A Petri net class will be identified for which some notions of fairness collapse to a single one. Even more distinctions can be made in a Turing-powerful system model.