Hypercube geodesics with few colour changes
Combinatorics
2026-05-29 v3
Abstract
What is the maximum, over all 2-colourings of the edges of the -dimensional hypercube , of the minimal number of times a path between a vertex and its antipode changes colour? A conjecture of Norine, in a form due to Feder and Subi, states that this maximum should be 1. The previous best-known upper bound on the number of colour changes was due to Kirchweger, Peitl, Subercaseaux, and Szeider. We improve this bound and answer a question of Leader and Long by finding a geodesic path with at most colour changes. In fact, we show that this is the expected number of colour changes for a uniformly random start vertex. This is optimal (up to the constant) when the start vertex is chosen uniformly at random.
Keywords
Cite
@article{arxiv.2605.20184,
title = {Hypercube geodesics with few colour changes},
author = {Lawrence Hollom},
journal= {arXiv preprint arXiv:2605.20184},
year = {2026}
}
Comments
8 pages, 1 figure