English

The surface of a sufficiently large sphere has chromatic number at most 7

Combinatorics 2021-07-27 v1

Abstract

We present a method to assign, for any radius rr greater than about 12.44, one of seven colors to each point in R3\mathbb{R}^3 lying at distance rr from the origin, such that no two points at unit distance from each other are assigned the same color. The existence of such a construction contrasts with the recent demonstration that, for any positive value ε\varepsilon, if no two points assigned the same color lie at any distance in [1,1+ε][1,1+\varepsilon] (and with certain other restrictions that are also satisfied with our coloring), then eight colors are needed for any finite r18r\ge18, even though seven colors suffice in the plane when ε721\varepsilon \leq\frac{\sqrt{7}}{2} - 1.

Keywords

Cite

@article{arxiv.2107.11900,
  title  = {The surface of a sufficiently large sphere has chromatic number at most 7},
  author = {Tomas Sirgedas},
  journal= {arXiv preprint arXiv:2107.11900},
  year   = {2021}
}