points in the plane
Source: Middle European Mathematical Olympiad 2013 T-4
May 17, 2014
combinatorics proposedcombinatorics
Problem Statement
Consider finitely many points in the plane with no three points on a line. All these points can be coloured red or green such that any triangle with vertices of the same colour contains at least one point of the other colour in its interior.
What is the maximal possible number of points with this property?