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Mathematics > Combinatorics

Title: Extensions of discrete Helly theorems for boxes

Abstract: We prove extensions of Halman's discrete Helly theorem for axis-parallel boxes in $\mathbb{R}^d$. Halman's theorem says that, given a set $S$ in $\mathbb{R}^d$, if $F$ is a finite family of axis-parallel boxes such that the intersection of any $2d$ contains a point of $S$, then the intersection of $F$ contains a point of $S$. We prove colorful, fractional, and quantitative versions of Halman's theorem. For the fractional versions, it is enough to check that many $(d+1)$-tuples of the family contain points of $S$. Among the colorful versions we include variants where the coloring condition is replaced by an arbitrary matroid. Our results generalize beyond axis-parallel boxes to $H$-convex sets.
Comments: 13 pages, 1 figure
Subjects: Combinatorics (math.CO)
MSC classes: 52A35
Cite as: arXiv:2404.14308 [math.CO]
  (or arXiv:2404.14308v1 [math.CO] for this version)

Submission history

From: Pablo Soberón [view email]
[v1] Mon, 22 Apr 2024 16:10:12 GMT (21kb,D)

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