A note on lenses in arrangements of pairwise intersecting circles in the plane

Fuente: arXiv
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Main Author: Pinchasi, Rom
Format: Preprint
Published: 2024
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author Pinchasi, Rom
author_facet Pinchasi, Rom
contents Let $\F$ be a family of $n$ pairwise intersecting circles in the plane. We show that the number of lenses, that is convex digons, in the arrangement induced by $\F$ is at most $2n-2$. This bound is tight. Furthermore, if no two circles in $\F$ touch, then the geometric graph $G$ on the set of centers of the circles in $\F$ whose edges correspond to the lenses generated by $\F$ does not contain pairs of avoiding edges. That is, $G$ does not contain pairs of edges that are opposite edges in a convex quadrilateral. Such graphs are known to have at most $2n-2$ edges.
format Preprint
id arxiv_https___arxiv_org_abs_2403_05270
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A note on lenses in arrangements of pairwise intersecting circles in the plane
Pinchasi, Rom
Combinatorics
Let $\F$ be a family of $n$ pairwise intersecting circles in the plane. We show that the number of lenses, that is convex digons, in the arrangement induced by $\F$ is at most $2n-2$. This bound is tight. Furthermore, if no two circles in $\F$ touch, then the geometric graph $G$ on the set of centers of the circles in $\F$ whose edges correspond to the lenses generated by $\F$ does not contain pairs of avoiding edges. That is, $G$ does not contain pairs of edges that are opposite edges in a convex quadrilateral. Such graphs are known to have at most $2n-2$ edges.
title A note on lenses in arrangements of pairwise intersecting circles in the plane
topic Combinatorics
url https://arxiv.org/abs/2403.05270