A polynomial verification algorithm for safe diagnosability of fuzzy discrete-event systems

In this paper, we investigate the verification issue for safe diagnosability of fuzzy discrete-event systems (FDESs). In order to guarantee that faults occurring in a safe diagnosable fuzzy system can be detected with a certain degree, and the detection may be completed before any unsafe behavior is executed, we construct a nondeterministic automaton, namely verifier, to check whether a certain forbidden operation is executed in the failed mode of fuzzy system. Then a necessary and sufficient condition for verifying the safe diagnosability of FDESs is proposed. It is illustrated that the verifier of an FDES can be constructed with a polynomial complexity, and the verification for its safe diagnosability can be realized within polynomial time.