Comments on “Maximally permissive supervisor synthesis based on a new constraint transformation method” [Automatica 48 (2012), 1097-1101]

This note shows by means of simple counterexamples that some key results presented by Luo et al. on the synthesis of maximally permissive supervisors based on the Uncontrollable Transition Gain Transformation method are incorrect. As a result, the transformation of inadmissible generalized mutual exclusion constraints for Petri nets is still an open issue.