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چکیده
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Facility location of two producers with preference of customers is discussed in this paper. Because of the di erences between two producers in terms of their in uence on the market, the problem was formulated as a bi-level integer mathematical programming model with binary variables. It was considered that both leader and follower had some facilities at rst and would open new facilities, which might lead to changes in the allocation of facilities and customers. To solve the problem, two metaheuristic algorithms based on Genetic Algorithm (GA) and a hybrid of GA and Ant Colony Optimization (ACO) were proposed. In the rst section of each algorithm, the location of facilities for two producers was determined; in the second section, each customer selects a facility. Upper bound of the competitive facility location problem was determined by solving the upper-level problem as an integer linear programming model without considering the follower's decision. To evaluate the eciency of the proposed algorithms, the enumeration technique was employed to nd an optimal solution. Computational results demonstrated that all of the developed algorithms were capable of achieving an optimal solution to small-sized problems and a high-quality solution within a reasonable computational time to medium- and large-scale problems.
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