Speed-up techniques for solving large-scale bTSP with the Two-Phase Pareto Local Search

We first present a method, called Two-Phase Pareto Local Search, to find a good approximation of the efficient set of the biobjective traveling salesman problem. In the first phase of the method, an initial population composed of an approximation of the extreme supported efficient solutions is generated. We use as second phase a Pareto Local Search method applied to all solutions of the initial population. We show that using the combination of these two techniques: good initial population generation and Pareto Local Search gives good results, without numerical parameters. As the computational time of the second phase grows exponentially according to the instances size, speed-up techniques are used to considerably reduce the computational time of the second phase. It makes it possible to find good approximation of the efficient set of large-scale biobjective traveling salesman problems, in a reasonable resolution time.