English

The number of point-splitting circles

Combinatorics 2007-05-23 v1

Abstract

Let S be a set of 2n+1 points in the plane such that no three are collinear and no four are concyclic. A circle will be called point-splitting if it has 3 points of S on its circumference, n-1 points in its interior and n-1 in its exterior. We show the surprising property that S always has exactly n^2 point- splitting circles, and prove a more general result.

Keywords

Cite

@article{arxiv.math/0110209,
  title  = {The number of point-splitting circles},
  author = {Federico Ardila M},
  journal= {arXiv preprint arXiv:math/0110209},
  year   = {2007}
}

Comments

12 pages, 4 figures

R2 v1 2026-07-22T16:41:04.237Z