Cuboids are canonically Ramsey

Fuente: arXiv
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Main Author: Shaw, Benedict Randall
Format: Preprint
Published: 2026
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author Shaw, Benedict Randall
author_facet Shaw, Benedict Randall
contents We say a set of points $C\subset \mathbb{R}^n$ is canonically Ramsey if there is some set of points $S\subset \mathbb{R}^{n'}$ such that any colouring of $S$, with any number of colours, admits either a monochromatic or rainbow copy of $C$ -- that is to say, some set of points congruent to $C$ either all receive the same colour, or all receive different colours. Mao, Ozeki, and Wang introduced this notion, proving that 30-60-90 triangles are canonically Ramsey, since when various other canonically Ramsey configurations have been identified (by Gehér, Sagdeev, and Tóth, and others). Fang, Ge, Shu, Xu, Xu, and Yang showed that all triangles and rectangles are canonically Ramsey, and asked whether all cuboids are canonically Ramsey. Here cuboids are sets of the form $\{0,b_1\}\times\dots\times\{0,b_s\}$, and in particular may have dimension greater than three. We resolve this question, proving that all cuboids are canonically Ramsey.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02189
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cuboids are canonically Ramsey
Shaw, Benedict Randall
Combinatorics
05D10
We say a set of points $C\subset \mathbb{R}^n$ is canonically Ramsey if there is some set of points $S\subset \mathbb{R}^{n'}$ such that any colouring of $S$, with any number of colours, admits either a monochromatic or rainbow copy of $C$ -- that is to say, some set of points congruent to $C$ either all receive the same colour, or all receive different colours. Mao, Ozeki, and Wang introduced this notion, proving that 30-60-90 triangles are canonically Ramsey, since when various other canonically Ramsey configurations have been identified (by Gehér, Sagdeev, and Tóth, and others). Fang, Ge, Shu, Xu, Xu, and Yang showed that all triangles and rectangles are canonically Ramsey, and asked whether all cuboids are canonically Ramsey. Here cuboids are sets of the form $\{0,b_1\}\times\dots\times\{0,b_s\}$, and in particular may have dimension greater than three. We resolve this question, proving that all cuboids are canonically Ramsey.
title Cuboids are canonically Ramsey
topic Combinatorics
05D10
url https://arxiv.org/abs/2603.02189