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Main Authors: Freij-Hollanti, Ragnar, Lundström, Teemu, Mori, Aki
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.17541
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author Freij-Hollanti, Ragnar
Lundström, Teemu
Mori, Aki
author_facet Freij-Hollanti, Ragnar
Lundström, Teemu
Mori, Aki
contents We give an explicit combinatorial description of the two-dimensional faces of both the order polytope $\mathcal{O}(P)$ and the chain polytope $\mathcal{C}(P)$ of a partially ordered set $P$. Using these descriptions, we show that for any $P$, $\mathcal{C}(P)$ has equally many square faces, and at least as many triangular faces, as $\mathcal{O}(P)$ does. Moreover, the inequality is shown to be strict except when $\mathcal{O}(P)$ and $\mathcal{C}(P)$ are unimodularly equivalent. This proves the case $i=2$ of a conjecture by Hibi and Li.
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id arxiv_https___arxiv_org_abs_2509_17541
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Two-Dimensional Faces of Order and Chain Polytopes
Freij-Hollanti, Ragnar
Lundström, Teemu
Mori, Aki
Combinatorics
We give an explicit combinatorial description of the two-dimensional faces of both the order polytope $\mathcal{O}(P)$ and the chain polytope $\mathcal{C}(P)$ of a partially ordered set $P$. Using these descriptions, we show that for any $P$, $\mathcal{C}(P)$ has equally many square faces, and at least as many triangular faces, as $\mathcal{O}(P)$ does. Moreover, the inequality is shown to be strict except when $\mathcal{O}(P)$ and $\mathcal{C}(P)$ are unimodularly equivalent. This proves the case $i=2$ of a conjecture by Hibi and Li.
title Two-Dimensional Faces of Order and Chain Polytopes
topic Combinatorics
url https://arxiv.org/abs/2509.17541