Some Remarks on “State Estimation and Fault Diagnosis of Labeled Time Petri Net Systems With Unobservable Transitions”

In this paper, we comment on the algorithm proposed in the paper mentioned in the title to define and construct a graph, called Modified State Class Graph (MSCG), which summarizes all possible evolutions of a Time Petri net. We first show that under the assumptions mentioned in such a paper, the proposed graph could be infinite. Then, we underline the requirement of revising the notation and adding some information on certain edges of the graph. Finally, we remark that the current version of the algorithm does not consider all possible evolutions of the net system. In the final part of the manuscript, we propose a revised algorithm for the definition and construction of the MSCG that overcomes all such limitations.