Two nearly equal distances in $R^d$

P. Erdős, E. Makai, J. Pach

A point set $P\subset {\mathbb{R}}^d$ is {\it separated} if the minimum distance between any two points in $P$ is at least $1$. For $d\ne 4,5,$ we determine, for every $t_1,t_2 \ge…