Given $2015$ points in the plane, show that if every four of them form a convex quadrilateral then the points are the vertices of a convex $2015-$sided polygon.
Source: India Postals 2015 Set 2
Tags: combinatorics, Convex hull
Given $2015$ points in the plane, show that if every four of them form a convex quadrilateral then the points are the vertices of a convex $2015-$sided polygon.