Multi-objective fully fuzzy linear programming problems with triangular fuzzy numbers

For checking the optimality of the objective function, we introduce a lexicographic order relation to compare two arbitrary triangular fuzzy numbers. Based on the order relation, the multi-objective fully fuzzy linear programming problem is converted into a crisp multi-level multi-objective linear programming problem, which may be solved by using the Min operator step by step. A numerical example is given to illustrate the validity of the proposed method.