On the existence of Petri net supervisors

The use of Petri net languages in supervisory control theory is discussed. It is shown that the trimming of an unbounded Petri net is not always possible. A class of Petri net languages, which may be generated by nonblocking generators, is defined. Necessary and sufficient conditions for the existence of a Petri net supervisor, under the hypothesis that the system's behavior and the legal behavior are both Petri net languages, are derived.<
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