The Matching Ramsey Number of Hypergraphs, Revisited

Fuente: arXiv
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Main Authors: Shaebani, Saeed, Alishahi, Meysam
Format: Preprint
Published: 2021
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author Shaebani, Saeed
Alishahi, Meysam
author_facet Shaebani, Saeed
Alishahi, Meysam
contents Suppose that a hypergraph ${\mathcal H}$ and an arbitrary nonempty (finite or infinite) set of available colors are given. Each color $x$ is associated with a frequency $τ(x)$, where the set of all such frequencies is bounded. We define a new parameter called the {\it $τ$-matching chromatic number}, denoted by $χ_M(τ, {\mathcal H})$, as the least possible number of colors required to color the edges of ${\mathcal H}$ in such a way that the size of each nonempty monochromatic matching does not exceed the frequency of the corresponding color associated to its edges. The well-known and extensively well-studied chromatic number of general Kneser hypergraph $χ\left( {\rm KG}^r({\mathcal H}) \right)$ is a special case of $χ_M(τ, {\mathcal H})$ when all color frequencies are the fixed constant $r-1$. In this paper, we establish sharp lower bounds for the parameter $χ_M(τ, {\mathcal H})$, utilizing the concepts of the alternation number and the equitable colorability defect.
format Preprint
id arxiv_https___arxiv_org_abs_2101_04701
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle The Matching Ramsey Number of Hypergraphs, Revisited
Shaebani, Saeed
Alishahi, Meysam
Combinatorics
05C15
Suppose that a hypergraph ${\mathcal H}$ and an arbitrary nonempty (finite or infinite) set of available colors are given. Each color $x$ is associated with a frequency $τ(x)$, where the set of all such frequencies is bounded. We define a new parameter called the {\it $τ$-matching chromatic number}, denoted by $χ_M(τ, {\mathcal H})$, as the least possible number of colors required to color the edges of ${\mathcal H}$ in such a way that the size of each nonempty monochromatic matching does not exceed the frequency of the corresponding color associated to its edges. The well-known and extensively well-studied chromatic number of general Kneser hypergraph $χ\left( {\rm KG}^r({\mathcal H}) \right)$ is a special case of $χ_M(τ, {\mathcal H})$ when all color frequencies are the fixed constant $r-1$. In this paper, we establish sharp lower bounds for the parameter $χ_M(τ, {\mathcal H})$, utilizing the concepts of the alternation number and the equitable colorability defect.
title The Matching Ramsey Number of Hypergraphs, Revisited
topic Combinatorics
05C15
url https://arxiv.org/abs/2101.04701