The Approximation Ratio of the 2-Opt Heuristic for the Metric Traveling Salesman Problem

09/26/2019

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by   Stefan Hougardy, et al.

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The 2-Opt heuristic is one of the simplest algorithms for finding good solutions to the metric Traveling Salesman Problem. It is the key ingredient to the well-known Lin-Kernighan algorithm and often used in practice. So far, only upper and lower bounds on the approximation ratio of the 2-Opt heuristic for the metric TSP were known. We prove that for the metric TSP with n cities, the approximation ratio of the 2-Opt heuristic is √(n/2) and that this bound is tight.