MathDB
n points on plane partitioned into m sets whose convex hulls have common point

Source: SRMC 2020 P4 - Silk Road

August 18, 2020
combinatorial geometrycombinatoricsConvex hull

Problem Statement

Prove that for any natural number m m there exists a natural number n n such that any n n distinct points on the plane can be partitioned into m m non-empty sets whose convex hulls have a common point. The convex hull of a finite set X X of points on the plane is the set of points lying inside or on the boundary of at least one convex polygon with vertices in X X , including degenerate ones, that is, the segment and the point are considered convex polygons. No three vertices of a convex polygon are collinear. The polygon contains its border.