Disjunctive fault prediction of decentralized discrete event systems: Verification, predictor design and K-copredictability

This paper deals with the problem of fault predictability of discrete event systems (DES) modeled by automata. The predictability property is approached in a disjunctive decentralized architecture, where the verdict that a fault will inevitably occur is given when at least one local agent is sure about its future occurrence. We adapt previous results on diagnosability verification to develop two new strategies to verify disjunctive fault predictability (called copredictability): the first one is based on a diagnoser-like test automaton, and the second one on by using verifiers. Necessary and sufficient conditions for a regular language to be copredictable are provided, and also a strategy for designing local fault predictor systems, to be used in online fault prediction. We also address the problem of verifying if all fault occurrences can be predicted at least K events prior to their occurrences (K-copredictability) and provide both a necessary and sufficient conditions for a regular language to be K-copredictable and an automaton-based test to verify if a regular language is K-copredictable.