Optimal Inapproximability of Promise Equations over Finite Groups

Fuente: arXiv
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Main Authors: Butti, Silvia, Larrauri, Alberto, Živný, Stanislav
Format: Preprint
Published: 2024
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author Butti, Silvia
Larrauri, Alberto
Živný, Stanislav
author_facet Butti, Silvia
Larrauri, Alberto
Živný, Stanislav
contents A celebrated result of Hastad established that, for any constant $\varepsilon>0$, it is NP-hard to find an assignment satisfying a $(1/|G|+\varepsilon)$-fraction of the constraints of a given 3-LIN instance over an Abelian group $G$ even if one is promised that an assignment satisfying a $(1-\varepsilon)$-fraction of the constraints exists. Engebretsen, Holmerin, and Russell showed the same result for 3-LIN instances over any finite (not necessarily Abelian) group. In other words, for almost-satisfiable instances of 3-LIN the random assignment achieves an optimal approximation guarantee. We prove that the random assignment algorithm is still best possible under a stronger promise that the 3-LIN instance is almost satisfiable over an arbitrarily more restrictive group.
format Preprint
id arxiv_https___arxiv_org_abs_2411_01630
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optimal Inapproximability of Promise Equations over Finite Groups
Butti, Silvia
Larrauri, Alberto
Živný, Stanislav
Computational Complexity
Discrete Mathematics
A celebrated result of Hastad established that, for any constant $\varepsilon>0$, it is NP-hard to find an assignment satisfying a $(1/|G|+\varepsilon)$-fraction of the constraints of a given 3-LIN instance over an Abelian group $G$ even if one is promised that an assignment satisfying a $(1-\varepsilon)$-fraction of the constraints exists. Engebretsen, Holmerin, and Russell showed the same result for 3-LIN instances over any finite (not necessarily Abelian) group. In other words, for almost-satisfiable instances of 3-LIN the random assignment achieves an optimal approximation guarantee. We prove that the random assignment algorithm is still best possible under a stronger promise that the 3-LIN instance is almost satisfiable over an arbitrarily more restrictive group.
title Optimal Inapproximability of Promise Equations over Finite Groups
topic Computational Complexity
Discrete Mathematics
url https://arxiv.org/abs/2411.01630