New aspect of solving the Fuzzy Hierarchical decision-making problem in Bilevel

In several essays, Zhang , Lu and Dillon to solve the Fuzzy bilevel linear programming problem have used two ideas which can not be true in general. One is that the ranking method of fuzzy numbers which is used, is not always true, and the other one is that for solving one Fuzzy number linear programming problem, they turn it into a biobjective problem for an arbitrary λ-cut which itself is a more difficult problem and moreover it is contradictory to the nature of the interval linear programming problem. In this essay, based on the interval linear programming problem, a method of obtaining an approximate fuzzy number for the optimal objective function value of Fuzzy bilevel linear programming problem is presented

Keywords:

Hierarchical optimization , Interval numbers , Bilevel programming