An analysis of the extended Christofides heuristic for the k-depot TSP

We study an extension of the classical traveling salesman problem (TSP) to a situation with k≥2 depots at each of which a distinct salesman is based. We show that a non-trivial extension of the well-known Christofides heuristic has a tight approximation ratio of 2−1/k, which improves on the known 2-approximation algorithm from the literature.