Quentin Dubroff, Rutgers University

Abstract

The orchard problem asks for the maximum number of collinear triples in a finite set of points in the plane. Very recently, Green and Tao gave an upper bound on this old problem which exactly matches the known lower bound. I will construct the set which achieves this lower bound, and I'll mention some connections with number theory and algebraic geometry. I will also discuss the conjectured generalization of this problem to collinear k-tuples by Erdős, which is worth 100 dollars.