This paper presents a decision making system for semiconductor wafer fabrication facilities, or wafer fabs, with hard inter-operation temporal constraints. The decision making system is developed based on a multi-agent architecture that is composed of scheduling agents, workcell agents, machine agents, and product agents. The decision making problem is to allocate lots into each workcell to satisfy both logical and temporal constraints. A dynamic planning-based approach is adopted for the decision making mechanism so that the dynamic behaviors of the wafer fab such as aperiodic lot arrivals and reconfiguration can be taken into consideration. The scheduling agents compute quasi-optimal schedules through a bidding mechanism with the workcell agents. The proposed decision making mechanism uses a concept of temporal constraint sets to obtain a feasible schedule in polynomial steps. The computational complexity of the decision making mechanism is proven to be O(L^3\ud7L), where L is the number of operations of a lot and L is the cardinality of the temporal constraint set.
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