Max-norm Ramsey Theory

Fuente: arXiv
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Main Authors: Frankl, Nóra, Kupavskii, Andrey, Sagdeev, Arsenii
Format: Preprint
Published: 2021
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author Frankl, Nóra
Kupavskii, Andrey
Sagdeev, Arsenii
author_facet Frankl, Nóra
Kupavskii, Andrey
Sagdeev, Arsenii
contents Given a metric space $\mathcal{M}$ that contains at least two points, the chromatic number $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ is defined as the minimum number of colours needed to colour all points of an $n$-dimensional space $\mathbb{R}^n_{\infty}$ with the max-norm such that no isometric copy of $\mathcal{M}$ is monochromatic. The last two authors have recently shown that the value $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ grows exponentially for all finite $\mathcal{M}$. In the present paper we refine this result by giving the exact value $χ_{\mathcal{M}}$ such that $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right) = (χ_{\mathcal{M}}+o(1))^n$ for all 'one-dimensional' $\mathcal{M}$ and for some of their Cartesian products. We also study this question for infinite $\mathcal{M}$. In particular, we construct an infinite $\mathcal{M}$ such that the chromatic number $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ tends to infinity as $n \rightarrow \infty$.
format Preprint
id arxiv_https___arxiv_org_abs_2111_08949
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Max-norm Ramsey Theory
Frankl, Nóra
Kupavskii, Andrey
Sagdeev, Arsenii
Combinatorics
05D10, 05C15, 52C10
Given a metric space $\mathcal{M}$ that contains at least two points, the chromatic number $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ is defined as the minimum number of colours needed to colour all points of an $n$-dimensional space $\mathbb{R}^n_{\infty}$ with the max-norm such that no isometric copy of $\mathcal{M}$ is monochromatic. The last two authors have recently shown that the value $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ grows exponentially for all finite $\mathcal{M}$. In the present paper we refine this result by giving the exact value $χ_{\mathcal{M}}$ such that $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right) = (χ_{\mathcal{M}}+o(1))^n$ for all 'one-dimensional' $\mathcal{M}$ and for some of their Cartesian products. We also study this question for infinite $\mathcal{M}$. In particular, we construct an infinite $\mathcal{M}$ such that the chromatic number $χ\left(\mathbb{R}^n_{\infty}, \mathcal{M} \right)$ tends to infinity as $n \rightarrow \infty$.
title Max-norm Ramsey Theory
topic Combinatorics
05D10, 05C15, 52C10
url https://arxiv.org/abs/2111.08949