English

High-dimensional tennis balls

Functional Analysis 2021-10-07 v2 Metric Geometry

Abstract

We show that there exist constants α,ϵ>0\alpha,\epsilon>0 such that for every positive integer nn there is a continuous odd function f:SmSnf:S^m\to S^n, with mαnm\geq \alpha n, such that the ϵ\epsilon-expansion of the image of ff does not contain a great circle. We also show how this result is connected to a conjecture of Vitali Milman about well-complemented almost Euclidean subspaces of spaces uniformly isomorphic to 2n\ell_2^n.

Keywords

Cite

@article{arxiv.1912.10679,
  title  = {High-dimensional tennis balls},
  author = {W. T. Gowers and K. Wyczesany},
  journal= {arXiv preprint arXiv:1912.10679},
  year   = {2021}
}

Comments

21 pages

R2 v1 2026-06-23T12:54:17.115Z