English

Everywhere unbalanced configurations

Combinatorics 2025-04-08 v2

Abstract

An old problem in discrete geometry, originating with Kupitz, asks whether there is a fixed natural number kk such that every finite set of points in the plane has a line through at least two of its points where the number of points on either side of this line differ by at most kk. We give a negative answer to a natural variant of this problem, showing that for every natural number kk there exists a finite set of points in the plane together with a pseudoline arrangement such that each pseudoline contains at least two points and there is a pseudoline through any pair of points where the number of points on either side of each pseudoline differ by at least kk. Moreover, we may find such a configuration with at most 22ck2^{2^{ck}} points, which, by a result of Pinchasi, is best possible up to the value of the constant cc.

Keywords

Cite

@article{arxiv.2308.02466,
  title  = {Everywhere unbalanced configurations},
  author = {David Conlon and Jeck Lim},
  journal= {arXiv preprint arXiv:2308.02466},
  year   = {2025}
}

Comments

28 pages, 24 figures

R2 v1 2026-06-28T11:48:19.267Z