A non-face characterization of spheres on few vertices

Fuente: arXiv
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Main Authors: Huang, Shuai, Miller, Jasper, Rose-Levine, Daniel, Simon, Steven
Format: Preprint
Published: 2025
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author Huang, Shuai
Miller, Jasper
Rose-Levine, Daniel
Simon, Steven
author_facet Huang, Shuai
Miller, Jasper
Rose-Levine, Daniel
Simon, Steven
contents We prove a relatively simple combinatorial characterization of simplicial $d$-spheres on $d+4$ vertices. Our criteria are given in terms of the intersection patterns of a simplicial complex's family of minimal non-faces. Namely, let $Σ$ be a simplicial complex on $d+4$ vertices and let $\mathcal{F}$ be its family of minimal non-faces. Then $Σ$ is a $d$-sphere if and only if $|\mathcal{F}|=n\geq 3$ is odd and there is an ordering $A_0,\ldots, A_{n-1}$ of the minimal non-faces, indices taken modulo $n$, such that successive $A_i$ are disjoint and the alternating $\frac{(n-1)}{2}$-fold intersections $A_i\cap A_{i+2} \cap A_{i+4} \cap \cdots \cap A_{i+n-3}$ partition the vertex set.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06120
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A non-face characterization of spheres on few vertices
Huang, Shuai
Miller, Jasper
Rose-Levine, Daniel
Simon, Steven
Combinatorics
05E45, 52B35, 52B12
We prove a relatively simple combinatorial characterization of simplicial $d$-spheres on $d+4$ vertices. Our criteria are given in terms of the intersection patterns of a simplicial complex's family of minimal non-faces. Namely, let $Σ$ be a simplicial complex on $d+4$ vertices and let $\mathcal{F}$ be its family of minimal non-faces. Then $Σ$ is a $d$-sphere if and only if $|\mathcal{F}|=n\geq 3$ is odd and there is an ordering $A_0,\ldots, A_{n-1}$ of the minimal non-faces, indices taken modulo $n$, such that successive $A_i$ are disjoint and the alternating $\frac{(n-1)}{2}$-fold intersections $A_i\cap A_{i+2} \cap A_{i+4} \cap \cdots \cap A_{i+n-3}$ partition the vertex set.
title A non-face characterization of spheres on few vertices
topic Combinatorics
05E45, 52B35, 52B12
url https://arxiv.org/abs/2507.06120