Lawrence E. Holloway A. S. Khare Yu Gong Computing bounds for forbidden State reachability functions for controlled Petri nets. 219-228 2004 34 IEEE Transactions on Systems, Man, and Cybernetics, Part A 2 http://doi.ieeecomputersociety.org/10.1109/TSMCA.2003.822279 db/journals/tsmc/tsmca34.html#HollowayKG04