Low degree sum-of-squares bounds for the stability number: a copositive approach

Fuente: arXiv
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Auteurs principaux: Vargas, Luis Felipe, Vera, Juan C., Dickinson, Peter J. C.
Format: Preprint
Publié: 2025
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author Vargas, Luis Felipe
Vera, Juan C.
Dickinson, Peter J. C.
author_facet Vargas, Luis Felipe
Vera, Juan C.
Dickinson, Peter J. C.
contents The stability number of a graph $G$, denoted as $α(G)$, is the maximum size of an independent (stable) set in $G$. Semidefinite programming (SDP) methods, which originated from Lovász's theta number and expanded through lift-and-project hierarchies as well as sums of squares (SOS) relaxations, provide powerful tools for approximating $α(G)$. We build upon the copositive formulation of $α(G)$ and introduce a novel SDP-based hierarchy of inner approximations to the copositive cone COP$_n$, which is derived from structured SOS representations. This hierarchy preserves essential structural properties that are missing in existing approaches, offers an SDP feasibility formulation at each level despite its non-convexity, and converges finitely to $α(G)$. Our results include examples of graph families that require at least $α(G) - 1$ levels for related hierarchies, indicating the tightness of the de Klerk-Pasechnik conjecture. Notably, on those graph families, our hierarchy achieves $α(G)$ in a single step.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04949
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Low degree sum-of-squares bounds for the stability number: a copositive approach
Vargas, Luis Felipe
Vera, Juan C.
Dickinson, Peter J. C.
Optimization and Control
Combinatorics
The stability number of a graph $G$, denoted as $α(G)$, is the maximum size of an independent (stable) set in $G$. Semidefinite programming (SDP) methods, which originated from Lovász's theta number and expanded through lift-and-project hierarchies as well as sums of squares (SOS) relaxations, provide powerful tools for approximating $α(G)$. We build upon the copositive formulation of $α(G)$ and introduce a novel SDP-based hierarchy of inner approximations to the copositive cone COP$_n$, which is derived from structured SOS representations. This hierarchy preserves essential structural properties that are missing in existing approaches, offers an SDP feasibility formulation at each level despite its non-convexity, and converges finitely to $α(G)$. Our results include examples of graph families that require at least $α(G) - 1$ levels for related hierarchies, indicating the tightness of the de Klerk-Pasechnik conjecture. Notably, on those graph families, our hierarchy achieves $α(G)$ in a single step.
title Low degree sum-of-squares bounds for the stability number: a copositive approach
topic Optimization and Control
Combinatorics
url https://arxiv.org/abs/2509.04949