On the volume of the elliptope and related metric polytopes

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Hauptverfasser: Avis, David, Devroye, Luc
Format: Preprint
Veröffentlicht: 2026
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author Avis, David
Devroye, Luc
author_facet Avis, David
Devroye, Luc
contents In this paper, we investigate the relationships between the volumes of four convex bodies: the cut polytope, metric polytope, rooted metric polytope, and elliptope, defined on graphs with $n$ vertices. The cut polytope is contained in each of the other three, which, for optimization purposes, provide polynomial-time relaxations. It is therefore of interest to see how tight these relaxations are. Worst-case ratio bounds are well known, but these are limited to objective functions with non-negative coefficients. Volume ratios, pioneered by Jon Lee with several co-authors, give global bounds and are the subject of this paper. For the rooted metric polytope over the complete graph, we show that its volume is much greater than that of the elliptope. For the metric polytope, for small values of $n$, we show that its volume is smaller than that of the elliptope; however, for large values, volume estimates suggest the converse is true. We also give exact formulae for the volume of the cut polytope for some families of sparse graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2604_16735
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the volume of the elliptope and related metric polytopes
Avis, David
Devroye, Luc
Discrete Mathematics
Computational Geometry
90-02
G.2
In this paper, we investigate the relationships between the volumes of four convex bodies: the cut polytope, metric polytope, rooted metric polytope, and elliptope, defined on graphs with $n$ vertices. The cut polytope is contained in each of the other three, which, for optimization purposes, provide polynomial-time relaxations. It is therefore of interest to see how tight these relaxations are. Worst-case ratio bounds are well known, but these are limited to objective functions with non-negative coefficients. Volume ratios, pioneered by Jon Lee with several co-authors, give global bounds and are the subject of this paper. For the rooted metric polytope over the complete graph, we show that its volume is much greater than that of the elliptope. For the metric polytope, for small values of $n$, we show that its volume is smaller than that of the elliptope; however, for large values, volume estimates suggest the converse is true. We also give exact formulae for the volume of the cut polytope for some families of sparse graphs.
title On the volume of the elliptope and related metric polytopes
topic Discrete Mathematics
Computational Geometry
90-02
G.2
url https://arxiv.org/abs/2604.16735