Improved Helly numbers of product sets

Fuente: arXiv
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Hauptverfasser: Arun, Srinivas, Dillon, Travis
Format: Preprint
Veröffentlicht: 2024
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author Arun, Srinivas
Dillon, Travis
author_facet Arun, Srinivas
Dillon, Travis
contents A finite family $\mathcal F$ of convex sets is $k$-intersecting in $S \subseteq \mathbb{R}^d$ if the intersection of every subset of $k$ convex sets in $\mathcal F$ contains a point in $S$. The Helly number of $S$ is the minimum $k$, if it exists, such that every $k$-intersecting family contains a point of $S$ in its intersection. In this paper, we improve bounds on the Helly number of product sets of the form $A^d$ for various sets $A \subseteq \mathbb{R}$, including the ``exponential grid'' $A = \{α^n : n \in \mathbb{N}\}$ and sets $A\subseteq \mathbb{Z}$ defined by congruence relations.
format Preprint
id arxiv_https___arxiv_org_abs_2409_07262
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Improved Helly numbers of product sets
Arun, Srinivas
Dillon, Travis
Combinatorics
Metric Geometry
A finite family $\mathcal F$ of convex sets is $k$-intersecting in $S \subseteq \mathbb{R}^d$ if the intersection of every subset of $k$ convex sets in $\mathcal F$ contains a point in $S$. The Helly number of $S$ is the minimum $k$, if it exists, such that every $k$-intersecting family contains a point of $S$ in its intersection. In this paper, we improve bounds on the Helly number of product sets of the form $A^d$ for various sets $A \subseteq \mathbb{R}$, including the ``exponential grid'' $A = \{α^n : n \in \mathbb{N}\}$ and sets $A\subseteq \mathbb{Z}$ defined by congruence relations.
title Improved Helly numbers of product sets
topic Combinatorics
Metric Geometry
url https://arxiv.org/abs/2409.07262