Fun combinatorial geo
Source: IMC 2022 Day 2 Problem 8
August 5, 2022
probability and statsexpected valuecombinatoricscombinatorial geometryIMC 2022
Problem Statement
Let be integers, and let be a circle. Let blue points and red points be
chosen uniformly and independently at random on the circle . Denote by the intersection of the
convex hull of the red points and the convex hull of the blue points. Let be the number of vertices
of the convex polygon (in particular, when is empty). Find the expected value of .