English

Density Frankl-R\"{o}dl on the Sphere

Probability 2026-05-01 v4

Abstract

We establish a density variant of the Frankl-R\"{o}dl theorem on the sphere Sn1\mathbb{S}^{n-1}, which concerns avoiding pairs of vectors with a specific distance, or equivalently, a prescribed inner product. In particular, we establish lower bounds on the probability that a randomly chosen pair of such vectors lies entirely within a measurable subset ASn1A \subseteq \mathbb{S}^{n-1} of sufficiently large measure. Additionally, we prove a density version of spherical avoidance problems, which generalize from pairwise avoidance to broader configurations with prescribed pairwise inner products. Our framework encompasses a class of configurations we call inductive configurations, which include simplices with any prescribed inner product 1<r<1-1 < r < 1. As a consequence of our density statement, we show that all inductive configurations are sphere Ramsey.

Keywords

Cite

@article{arxiv.2505.09839,
  title  = {Density Frankl-R\"{o}dl on the Sphere},
  author = {Venkatesan Guruswami and Shilun Li},
  journal= {arXiv preprint arXiv:2505.09839},
  year   = {2026}
}
R2 v1 2026-06-28T23:33:46.409Z