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Main Authors: Pohoata, Cosmin, Yang, Kevin, Zhang, Shengtong
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.17149
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author Pohoata, Cosmin
Yang, Kevin
Zhang, Shengtong
author_facet Pohoata, Cosmin
Yang, Kevin
Zhang, Shengtong
contents We establish a theorem regarding the maximum size of an {\it{induced}} matching in the bipartite complement of the incidence graph of a set system $(X,\mathcal{F})$. We show that this quantity plus one provides an upper bound on the colorful Helly number of this set system, i.e. the minimum positive integer $N$ for which the following statement holds: if finite subfamilies $\mathcal{F}_1,\ldots, \mathcal{F}_{N} \subset \mathcal{F}$ are such that $\cap_{F \in \mathcal{F}_{i}} F = 0$ for every $i=1,\ldots,N$, then there exists $F_i \in \mathcal{F}_i$ such that $F_1 \cap \ldots \cap F_{N} = \emptyset$. We will also discuss some natural refinements of this result and applications.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17149
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Colorful Helly via induced matchings
Pohoata, Cosmin
Yang, Kevin
Zhang, Shengtong
Combinatorics
We establish a theorem regarding the maximum size of an {\it{induced}} matching in the bipartite complement of the incidence graph of a set system $(X,\mathcal{F})$. We show that this quantity plus one provides an upper bound on the colorful Helly number of this set system, i.e. the minimum positive integer $N$ for which the following statement holds: if finite subfamilies $\mathcal{F}_1,\ldots, \mathcal{F}_{N} \subset \mathcal{F}$ are such that $\cap_{F \in \mathcal{F}_{i}} F = 0$ for every $i=1,\ldots,N$, then there exists $F_i \in \mathcal{F}_i$ such that $F_1 \cap \ldots \cap F_{N} = \emptyset$. We will also discuss some natural refinements of this result and applications.
title Colorful Helly via induced matchings
topic Combinatorics
url https://arxiv.org/abs/2501.17149