Neumann, FrankSudholt, DirkWitt, Carsten2009-05-122009-05-122008-03http://hdl.handle.net/2003/26150http://dx.doi.org/10.17877/DE290R-8721Ant colony optimization (ACO) is a metaheuristic that produces good results for a wide range of combinatorial optimization problems. Often such successful applications use a combination of ACO and local search procedures that improve the solutions constructed by the ants. In this paper, we study this combination from a theoretical point of view and point out situations where introducing local search into an ACO algorithm enhances the optimization process significantly. On the other hand, we illustrate the drawback that such a combination might have by showing that this may prevent an ACO algorithm from obtaining optimal solutions.en004Text