Efficient optimization of the Held–Karp lower bound

Given a weighted undirected graph $G=(V,E)$, the Held–Karp lower bound for the Traveling Salesman Problem (TSP) is obtained by selecting an arbitrary vertex $\bar{p} \in V$, by computing a minimum cost tree spanning $V \backslash \lbrace \bar{p}\rbrace $ and adding two minimum cost edges adjacent to...

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Bibliographic Details
Main Author: Righini, Giovanni
Format: Article
Language:English
Published: Université de Montpellier 2021-11-01
Series:Open Journal of Mathematical Optimization
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Online Access:https://ojmo.centre-mersenne.org/articles/10.5802/ojmo.11/
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Summary:Given a weighted undirected graph $G=(V,E)$, the Held–Karp lower bound for the Traveling Salesman Problem (TSP) is obtained by selecting an arbitrary vertex $\bar{p} \in V$, by computing a minimum cost tree spanning $V \backslash \lbrace \bar{p}\rbrace $ and adding two minimum cost edges adjacent to $\bar{p}$. In general, different selections of vertex $\bar{p}$ provide different lower bounds. In this paper it is shown that the selection of vertex $\bar{p}$ can be optimized, to obtain the largest possible Held–Karp lower bound, with the same worst-case computational time complexity required to compute a single minimum spanning tree. Although motivated by the optimization of the Held–Karp lower bound for the TSP, the algorithm solves a more general problem, allowing for the efficient pre-computation of alternative minimum spanning trees in weighted graphs where any vertex can be deleted.
ISSN:2777-5860