English

Canonical theorems in geometric Ramsey theory

Combinatorics 2026-02-03 v2

Abstract

In Euclidean Ramsey Theory usually we are looking for monochromatic configurations in the Euclidean space, whose points are colored with a fixed number of colors. In the canonical version, the number of colors is arbitrary, and we are looking for an `unavoidable' set of colorings of a finite configuration, that is a set of colorings with the property that one of them always appears in any coloring of the space. This set definitely includes the monochromatic and the rainbow colorings. In the present paper, we prove the following two results of this type. First, for any acute triangle TT, and any coloring of R3\mathbb{R}^3, there is either a monochromatic or a rainbow copy of TT. Second, for every mm, there exists a sufficiently large nn such that in any coloring of Rn\mathbb{R}^n, there exists either a monochromatic or a rainbow mm-dimensional unit hypercube. In the maximum norm, \ell_{\infty}, we have a much stronger statement. For every finite MM, there exits an nn such that in any coloring of Rn\mathbb{R}_\infty^n, there is either a monochromatic or a rainbow isometric copy of MM.

Keywords

Cite

@article{arxiv.2404.11454,
  title  = {Canonical theorems in geometric Ramsey theory},
  author = {Panna Gehér and Arsenii Sagdeev and Géza Tóth},
  journal= {arXiv preprint arXiv:2404.11454},
  year   = {2026}
}

Comments

9 pages, 3 figures