An interdiction/fortification location problem deals with finding the locations of resources and customer-facility assignments. Due to the special characteristics of the problem, the overall performance of the system depends on interdiction/fortification operations and the demand of customers. Therefore, the design of efficient systems is a remarkable issue to be considered. In this paper, a new point of view in the field of mathematical modeling of p-median systems in terms of fuzzy theory has been allocated and a bi-level programming is applied. It is assumed that the demand of customers and fortification/interdiction resources are imprecise. For solving this model, the bi-level problem is converted to a single level problem on using the Karush-Kuhn-Tucker (KKT) conditions. The single level model can be solved to optimality using CPLEX. Finally, a test problem is presented and the results are analyzed.
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