A novel ant colony system with double pheromones for the generalized TSP

The Generalized Traveling Salesman Problem (GTSP) is an extension of the classical traveling salesman problem and has many interesting applications. The GTSP is known to be an NP-hard problem. In this paper we present a novel ant colony system with double pheromones for solving the GTSP. Meanwhile, to avoid locking into local minima, an effectively local searching technique and a novel mutation process are also introduced into this method according to the characteristic of the GTSP. Experimental results on numerous TSPlib instances show that the proposed method is significantly superior to the state-of-the-art methods.