An Efficient Testing for the Detection of Trajectories in Discrete-Event Systems Modelled by S-Nets

This paper addresses the problem of the detection of sequences of event executed in a Discrete-Event System modelled by Petri Nets. The nets are equipped with output symbols that an external observer is allowed to detect. To provide efficient solutions, the focus of this work is a subclass of nets called S-Systems. The construction of the Sequence-Detectability table leads to a necessary and sufficient condition for the characterization of the sequence detection in the case of safe nets. The safeness requirement is relaxed and its implication on the sequence detection is analyzed. Moreover, the utility of the sequence detectability in the analysis of the observability of the net is studied. An example illustrates the concepts and main results of this paper.