Dual Charging for Half-Integral TSP

Fuente: arXiv
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Main Authors: Klein, Nathan, Taziki, Mehrshad
Format: Preprint
Published: 2025
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author Klein, Nathan
Taziki, Mehrshad
author_facet Klein, Nathan
Taziki, Mehrshad
contents We show that the max entropy algorithm is a randomized 1.49776 approximation for half-integral TSP, improving upon the previous known bound of 1.49993 from Karlin et al. This also improves upon the best-known approximation for half-integral TSP due to Gupta et al. Our improvement results from using the dual, instead of the primal, to analyze the expected cost of the matching. We believe this method of analysis could lead to a simpler proof that max entropy is a better-than-3/2 approximation in the general case. We also give a 1.4671 approximation for half integral LP solutions with no proper minimum cuts and an even number of vertices, improving upon the bound of Haddadan and Newman of 1.476. We then extend the analysis to the case when there are an odd number of vertices $n$ at the cost of an additional $O(1/n)$ factor.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17999
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dual Charging for Half-Integral TSP
Klein, Nathan
Taziki, Mehrshad
Data Structures and Algorithms
We show that the max entropy algorithm is a randomized 1.49776 approximation for half-integral TSP, improving upon the previous known bound of 1.49993 from Karlin et al. This also improves upon the best-known approximation for half-integral TSP due to Gupta et al. Our improvement results from using the dual, instead of the primal, to analyze the expected cost of the matching. We believe this method of analysis could lead to a simpler proof that max entropy is a better-than-3/2 approximation in the general case. We also give a 1.4671 approximation for half integral LP solutions with no proper minimum cuts and an even number of vertices, improving upon the bound of Haddadan and Newman of 1.476. We then extend the analysis to the case when there are an odd number of vertices $n$ at the cost of an additional $O(1/n)$ factor.
title Dual Charging for Half-Integral TSP
topic Data Structures and Algorithms
url https://arxiv.org/abs/2507.17999