English

Antipodal paths in covers of spheres

Algebraic Topology 2026-07-15 v1 Combinatorics

Abstract

In this note we show that if the sphere Sn\mathbb{S}^n is covered by kk open sets with n2k2n \geq 2k-2, then one of these sets contains a path with antipodal endpoints. This is best possible in the sense that the statement fails for n<2k2n < 2k-2. The result can be seen as a spherical analogue of a well-known conjecture of Norine on edge-colourings of the discrete hypercube.

Keywords

Cite

@article{arxiv.2607.13964,
  title  = {Antipodal paths in covers of spheres},
  author = {David Ellis and Maria-Romina Ivan and Imre Leader and John M. Mackay},
  journal= {arXiv preprint arXiv:2607.13964},
  year   = {2026}
}

Comments

3 pages. Comments (by email) welcome