Simplicial complexes with many facets are vertex decomposable

Fuente: arXiv
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Main Authors: Dochtermann, Anton, Nair, Ritika, Schweig, Jay, Van Tuyl, Adam, Woodroofe, Russ
Format: Preprint
Published: 2024
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_version_ 1866916507994292224
author Dochtermann, Anton
Nair, Ritika
Schweig, Jay
Van Tuyl, Adam
Woodroofe, Russ
author_facet Dochtermann, Anton
Nair, Ritika
Schweig, Jay
Van Tuyl, Adam
Woodroofe, Russ
contents Suppose $Δ$ is a pure simplicial complex on $n$ vertices having dimension $d$ and let $c = n-d-1$ be its codimension in the simplex. Terai and Yoshida proved that if the number of facets of $Δ$ is at least $\binom{n}{c}-2c+1$, then $Δ$ is Cohen-Macaulay. We improve this result by showing that these hypotheses imply the stronger condition that $Δ$ is vertex decomposable. We give examples to show that this bound is optimal, and that the conclusion cannot be strengthened to the class of matroids or shifted complexes. We explore an application to Simon's Conjecture and discuss connections to other results from the literature.
format Preprint
id arxiv_https___arxiv_org_abs_2403_07316
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Simplicial complexes with many facets are vertex decomposable
Dochtermann, Anton
Nair, Ritika
Schweig, Jay
Van Tuyl, Adam
Woodroofe, Russ
Combinatorics
Commutative Algebra
05E40, 05E45, 13F55
Suppose $Δ$ is a pure simplicial complex on $n$ vertices having dimension $d$ and let $c = n-d-1$ be its codimension in the simplex. Terai and Yoshida proved that if the number of facets of $Δ$ is at least $\binom{n}{c}-2c+1$, then $Δ$ is Cohen-Macaulay. We improve this result by showing that these hypotheses imply the stronger condition that $Δ$ is vertex decomposable. We give examples to show that this bound is optimal, and that the conclusion cannot be strengthened to the class of matroids or shifted complexes. We explore an application to Simon's Conjecture and discuss connections to other results from the literature.
title Simplicial complexes with many facets are vertex decomposable
topic Combinatorics
Commutative Algebra
05E40, 05E45, 13F55
url https://arxiv.org/abs/2403.07316