This paper is concerned with a class of fully fuzzy bilevel linear programming problems where all the coefficients and decision\nvariables of both objective functions and the constraints are fuzzy numbers. A new approach based on deviation degree measures\nand a ranking function method is proposed to solve these problems.We first introduce concepts of the feasible region and the fuzzy\noptimal solution of a fully fuzzy bilevel linear programming problem. In order to obtain a fuzzy optimal solution of the problem,\nwe apply deviation degree measures to deal with the fuzzy constraints and use a ranking function method of fuzzy numbers to rank\nthe upper and lower level fuzzy objective functions. Then the fully fuzzy bilevel linear programming problem can be transformed\ninto a deterministic bilevel programming problem. Considering the overall balance between improving objective function values\nand decreasing allowed deviation degrees, the computational procedure for finding a fuzzy optimal solution is proposed. Finally, a\nnumerical example is provided to illustrate the proposed approach.The results indicate that the proposed approach gives a better\noptimal solution in comparison with the existing method.
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