Marking Fairness in Petri Nets

We study fairness with respect to markings in Petri nets, which means no infinite execution sequence such that in the sequence some marking occurs only finitely often but it is an element of the forward set of a marking M which occurs infinitely often. First we show the transition strong fairness implies the marking fairness although the transition fairness and the marking fairness are quite different matters. And we find some relationship between the marking fairness and the frozen tokens. Then we prove that it can be controlled locally to make marking fairness.