Planar point sets with forbidden $4$-point patterns and few distinct distances
Combinatorics
2024-09-04 v1
Abstract
We show that for any large , there exists a set of points in the plane with distinct distances, such that any four points in the set determine at least five distinct distances. This answers (in the negative) a question of Erd\H{o}s. The proof combines an analysis by Dumitrescu of forbidden four-point patterns with an algebraic construction of Thiele and Dumitrescu (to eliminate parallelograms), as well as a randomized transformation of that construction (to eliminate most other forbidden patterns).
Cite
@article{arxiv.2409.01343,
title = {Planar point sets with forbidden $4$-point patterns and few distinct distances},
author = {Terence Tao},
journal= {arXiv preprint arXiv:2409.01343},
year = {2024}
}
Comments
7 pages, no figures