Comments on "Feedback control logic for forbidden-state problems of marked graphs: application to a real manufacturing system"

In the above paper (A. Ghaffari et al., IEEE Trans. Automat. Contr., vol. 48, pp. 18-29, Jan. 2003) an example was given for which it was claimed that there exists no optimal Petri net-based (monitor) controller. It is stated that by using another method it is possible to obtain an optimal PN-based (monitor) controller.