Abstract: Using the credibility method for interval numbers, the author gave the concepts of the feasible region and the optimal solution for the interval bilevel linear programming problem. By means of the optimal value interval methods of single level and bilevel programming as well as maxmin operator, the author constructed a deterministic equivalent model for the interval bilevel linear programming problem. A numerical example result show that the method is effective.

Key words: credibility, bilevel programming, interval bilevel programming, interval number