Abstract
In this paper, based on two new fuzzy arithmetic operations (i.e. Multiplication and Division) and fuzzy ordering on symmetric trapezoidal fuzzy numbers, a new algorithm is proposed to find directly a lexicographic/preemptive fuzzy optimal solution of a fuzzy lexicographic multi-objective linear programming (FLMOLP) problem and a properly fuzzy efficient solution of a fuzzy multi-objective linear programming (FMOLP) problem. Also, in optimality conditions, it is shown that how the FLMOLP problem can be solved by employing the preceding computations if the degree of priority of the fuzzy objective functions is changed. It should be noted that this permutation of fuzzy objective functions is a kind of sensitivity analysis which it may be happen due to the change in the management strategy with the passing of time.