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15 - Best-of-Many Christofides and Variants

Published online by Cambridge University Press:  14 November 2024

Vera Traub
Affiliation:
University of Bonn
Jens Vygen
Affiliation:
University of Bonn
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Summary

An, Kleinberg, and Shmoys were the first to beat Christofides’ algorithm for Path TSP. Their algorithm, which they called Best-of-Many Christofides, is very natural: Since an LP solution can be written as convex combination of spanning trees, we can do parity correction on each of these trees and output the best of the resulting tours. It turns out that this yields a better guarantee than the 5/3 that Christofides’ algorithm yields.

In this chapter, we analyze this algorithm and study various follow-up works that have yielded better and better approximation ratios; some of them also apply to general T-tours. This includes a structured decomposition into spanning trees (by Gottschalk and Vygen), Best-of-Many Christofides with lonely edge deletion (by Sebő and van Zuylen), and Traub’s T-tour algorithm.

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Publisher: Cambridge University Press
Print publication year: 2024

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