MathDB
Combo geo with circles

Source: 239 MO 2024 S8

May 22, 2024
combinatoricsgeometry

Problem Statement

There are 2n2n points on the plane. No three of them lie on the same straight line and no four lie on the same circle. Prove that it is possible to split these points into nn pairs and cover each pair of points with a circle containing no other points.