Effective Diversification of Ant-Based Search Using Colony Fission and Extinction

In ant colony optimization (ACO), to keep a balance between intensification and diversification of search is important. ASelite is one of the extensions of the original ant system (AS). In ASelite, elitist ants lay additional pheromone on the best found tour. By the intensification mechanism, ASelite can perform more rapid search for the optimal solution than conventional AS. On the other hand, however, this intensification of search causes the problem that ants are liable to fall into local optima. In this research, we aim to also improve the diversification of search while keeping the characteristic of ASelite. Therefore, we propose a new method using multiple colonies. In this method, multiple colonies search for the solution while doing colony fission and extinction. In addition, for the improvement of search performance by each single colony, we also propose the improved ASelite, ASelite with negative alpha. We applied the proposed methods to traveling salesman problems. Some experimental results show that search performance is improved and various solutions are acquired by the interaction of multiple colonies.