Finding One Local Optimum Is Easy -- but What About Two?

Fuente: arXiv
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Main Authors: Kobayashi, Yasuaki, Kurita, Kazuhiro, Yamaguchi, Yutaro
Format: Preprint
Published: 2025
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author Kobayashi, Yasuaki
Kurita, Kazuhiro
Yamaguchi, Yutaro
author_facet Kobayashi, Yasuaki
Kurita, Kazuhiro
Yamaguchi, Yutaro
contents The class PLS (Polynomial Local Search) captures the complexity of finding a solution that is locally optimal and has proven to be an important concept in the theory of local search. It has been shown that local search versions of various combinatorial optimization problems, such as Maximum Independent Set and Max Cut, are complete for this class. Such computational intractability typically arises in local search problems allowing arbitrary weights; in contrast, for unweighted problems, locally optimal solutions can be found in polynomial time under standard settings. In this paper, we pursue the complexity of local search problems from a different angle: We show that computing two locally optimal solutions is NP-hard for various natural unweighted local search problems, including Maximum Independent Set, Minimum Dominating Set, Max SAT, and Max Cut. We also discuss several tractable cases for finding two (or more) local optimal solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07524
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Finding One Local Optimum Is Easy -- but What About Two?
Kobayashi, Yasuaki
Kurita, Kazuhiro
Yamaguchi, Yutaro
Data Structures and Algorithms
Computational Complexity
The class PLS (Polynomial Local Search) captures the complexity of finding a solution that is locally optimal and has proven to be an important concept in the theory of local search. It has been shown that local search versions of various combinatorial optimization problems, such as Maximum Independent Set and Max Cut, are complete for this class. Such computational intractability typically arises in local search problems allowing arbitrary weights; in contrast, for unweighted problems, locally optimal solutions can be found in polynomial time under standard settings. In this paper, we pursue the complexity of local search problems from a different angle: We show that computing two locally optimal solutions is NP-hard for various natural unweighted local search problems, including Maximum Independent Set, Minimum Dominating Set, Max SAT, and Max Cut. We also discuss several tractable cases for finding two (or more) local optimal solutions.
title Finding One Local Optimum Is Easy -- but What About Two?
topic Data Structures and Algorithms
Computational Complexity
url https://arxiv.org/abs/2507.07524