Given a finite point set X in the plane, the degree of a pair {x,y}⊂X is the number of empty triangles t=conv{x,y,z}, where empty means t∩X={x,y,z}. Define degX as the maximal degree of a pair in X. Our main result is that if X is a random sample of n independent and uniform points from a fixed convex body, then degX≥cn/lnn in expectation.
@article{arxiv.1209.3928,
title = {Many empty triangles have a common edge},
author = {Imre Bárány and Jean-François Marckert and Matthias Reitzner},
journal= {arXiv preprint arXiv:1209.3928},
year = {2012}
}