Abstract: Developed in this paper is a new strategy for avoiding forbidden states of resource allocation systems. The strategy is based on Petri nets and their structural analysis, with the Petri nets bounded and covered by initial marked P-invariants. This approach is first to orderly conduct off-line computations of some special states or markings, such as dead(lock) markings, bad markings, and dangerous markings, of the system's Petri net model, and then make on-line the system never reach a forbidden state such as dead(lock) markings and bad markings. The major advantage of the technique lies in the fact taht it is suitable for much larger resource allocation systems than the most existing ones and the supervisory control is maximally permissive. Meanwhile, the computation is successfully avoided for the whole reachability graph of the Petri net of the system.

Key words: petri nets, avoid forbidden state, resource allocation systems, dangerous marking