English

Distinct Angles in General Position

Computational Geometry 2022-06-14 v2 Combinatorics Metric Geometry

Abstract

The Erd\H{o}s distinct distance problem is a ubiquitous problem in discrete geometry. Somewhat less well known is Erd\H{o}s' distinct angle problem, the problem of finding the minimum number of distinct angles between nn non-collinear points in the plane. Recent work has introduced bounds on a wide array of variants of this problem, inspired by similar variants in the distance setting. In this short note, we improve the best known upper bound for the minimum number of distinct angles formed by nn points in general position from O(nlog2(7))O(n^{\log_2(7)}) to O(n2)O(n^2). Before this work, similar bounds relied on projections onto a generic plane from higher dimensional space. In this paper, we employ the geometric properties of a logarithmic spiral, sidestepping the need for a projection. We also apply this configuration to reduce the upper bound on the largest integer such that any set of nn points in general position has a subset of that size with all distinct angles. This bound is decreased from O(nlog2(7)/3)O(n^{\log_2(7)/3}) to O(n1/2)O(n^{1/2}).

Keywords

Cite

@article{arxiv.2206.04367,
  title  = {Distinct Angles in General Position},
  author = {Henry L. Fleischmann and Sergei V. Konyagin and Steven J. Miller and Eyvindur A. Palsson and Ethan Pesikoff and Charles Wolf},
  journal= {arXiv preprint arXiv:2206.04367},
  year   = {2022}
}

Comments

Former Corollary 4.1 upgraded to Theorem 1.2 with improved bounds

R2 v1 2026-06-24T11:44:41.100Z