English

A Sylvester-Gallai result for concurrent lines in the complex plane

Combinatorics 2020-09-30 v2

Abstract

We show that if a set of points in C2\mathbb{C}^2 lies on a family of mm concurrent lines, and if one of those lines contains more than m2m-2 points, then there is a line passing through exactly two points of the set. The bound m2m-2 in our result is optimal. Our main theorem resolves a conjecture of Frank de Zeeuw, and generalizes a result of Kelly and Nwankpa.

Keywords

Cite

@article{arxiv.2007.03601,
  title  = {A Sylvester-Gallai result for concurrent lines in the complex plane},
  author = {Alex Cohen},
  journal= {arXiv preprint arXiv:2007.03601},
  year   = {2020}
}

Comments

16 pages, 6 figures; several revisions added for overall clarity

R2 v1 2026-06-23T16:55:32.352Z