English

Intersections of vertical lines with non-vertical lines

General Mathematics 2022-07-14 v1

Abstract

We answer negatively a question: if F\mathcal F is a family of n3n\geqslant 3 non-vertical, pairwise non-parallel lines on the plane and F=\bigcap \mathcal F=\emptyset, is there a vertical line LL such that LFL\cap\bigcup \mathcal F has exactly n1n-1 or n2n-2 points?

Cite

@article{arxiv.2207.06230,
  title  = {Intersections of vertical lines with non-vertical lines},
  author = {Mateusz Kula},
  journal= {arXiv preprint arXiv:2207.06230},
  year   = {2022}
}

Comments

I solved the problem while I was participating at the conference in B\k{e}dlewo. The problem is at the elementary level and can be applied to teach duality of points and lines

R2 v1 2026-06-25T00:52:58.097Z