Comparison of Different Topologies for Island-Based Multi-Colony Ant Algorithms for the Minimum Weight Vertex Cover Problem

The aim of this paper is compare the effect of using different topologies or connections between separate colonies in island based parallel implementations of the Ant Colony Optimization applied to the Minimum Weight Vertex Cover Problem. We investigated the sequential Ant Colony Optimization algorithms applied to the Minimum Weight Vertex Cover Problem before. Parallelization of population based algorithms using the island model is of great importance because it often gives super linear increase in performance. We observe the behavior of different parallel algorithms corresponding to several topologies and communication rules like fully connected, replace worst, ring and independent parallel runs. We also propose a variation of the algorithm corresponding to the ring topology that maintains the diversity of the search, but still moves to areas with better solutions and gives slightly better results even on a single processor with threads. Key-Words: Ant colony optimization, Minimum weight vertex cover problem, Parallel computing, Combinatorial optimization, Evolutionary computing