Shigemasa Takai

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Decentralized decision-making requires the interaction of various local decision-makers in order to arrive at a global decision. Limited sensing capabilities at each local site can create ambiguities in a decision-making process at each local site. We argue that such ambiguities are of differing gradations. We propose a framework for decentralized(More)
The task of decentralized decision-making involves interaction of a set of local decision-makers, each of which operates under limited sensing capabilities and is thus subjected to ambiguity during the process of decision-making. In our prior work, we made a key observation that such ambiguities are of differing gradations and presented a framework for(More)
For discrete event systems, we study the problem of predicting failures prior to their occurrence, also referred to as prognosis, in the inference-based decentralized framework where multiple decisionmakers interact to make the global prognostic decisions. We characterize the class of systems for which there are no missed detections (all failures can be(More)
A supervisor is said to be mutually nonblocking with respect to a pair of specifications if upon completing a task in any of the specifications, it can continue on to complete the task in the other specification, i.e., the two specifications do not block each other. The notion of mutually nonblocking supervisor was introduced in [4, 5]. In this paper we(More)
The reliable decentralized supervisory control of discrete event systems (DESs) with communication delays is investigated in this paper. For a system equipped with n local supervisors, we formalize the notion of k-reliable (1 ≤ k ≤ n) decentralized supervisor under communication delays, in which some local supervisors are allowed to fail and(More)
The task of decentralized decision-making involves interaction of a set of local decisionmakers, each of which operates under limited sensing capabilities and is thus subjected to ambiguity during the process of decision-making. In a prior work [2] we made an observation that such ambiguities are of differing gradations and presented a framework for(More)
We present fixed-point based characterization of several classes of co-observable languages that are of interest in the context of decentralized supervisory control of discrete event systems, including C&P∨D&A co-observable languages, C&P co-observable languages, and D&A co-observable languages [30]. We also provide formulae for computing super/sublanguages(More)