Max Cut with Small-Dimensional SDP Solutions

Fuente: arXiv
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Autori principali: Chang, Hsien-Chih, Ghoshal, Suprovat, Lee, Euiwoong
Natura: Preprint
Pubblicazione: 2026
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author Chang, Hsien-Chih
Ghoshal, Suprovat
Lee, Euiwoong
author_facet Chang, Hsien-Chih
Ghoshal, Suprovat
Lee, Euiwoong
contents We study the Max-Cut semidefinite programming (SDP) relaxation in the regime where a near-optimal solution admits a low-dimensional realization. While the Goemans--Williamson hyperplane rounding achieves the worst-case optimal approximation ratio $α_{GW}\approx 0.87856$, it is natural to ask whether one can beat $α_{GW}$ when the SDP solution lives in $\mathbb{R}^d$ for a small dimension $d$. We answer this in the affirmative for every fixed $d$: there is a polynomial-time rounding algorithm that, given a $d$-dimensional feasible solution to the standard Max-Cut SDP strengthened with triangle inequalities, produces a cut of expected value at least $(α_{GW}+2^{-O(d)})$ times the SDP value. Our improvement is driven by a new geometric anti-concentration lemma for signs of low-dimensional Gaussian projections.
format Preprint
id arxiv_https___arxiv_org_abs_2604_13971
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Max Cut with Small-Dimensional SDP Solutions
Chang, Hsien-Chih
Ghoshal, Suprovat
Lee, Euiwoong
Data Structures and Algorithms
We study the Max-Cut semidefinite programming (SDP) relaxation in the regime where a near-optimal solution admits a low-dimensional realization. While the Goemans--Williamson hyperplane rounding achieves the worst-case optimal approximation ratio $α_{GW}\approx 0.87856$, it is natural to ask whether one can beat $α_{GW}$ when the SDP solution lives in $\mathbb{R}^d$ for a small dimension $d$. We answer this in the affirmative for every fixed $d$: there is a polynomial-time rounding algorithm that, given a $d$-dimensional feasible solution to the standard Max-Cut SDP strengthened with triangle inequalities, produces a cut of expected value at least $(α_{GW}+2^{-O(d)})$ times the SDP value. Our improvement is driven by a new geometric anti-concentration lemma for signs of low-dimensional Gaussian projections.
title Max Cut with Small-Dimensional SDP Solutions
topic Data Structures and Algorithms
url https://arxiv.org/abs/2604.13971