3n+1 members in a club
Source: Kürschák 1987, problem 3
July 27, 2014
combinatorics unsolvedcombinatorics
Problem Statement
Any two members of a club with people plays ping-pong, tennis or chess with each other. Everyone has exactly partners who plays ping-pong, who play tennis and who play chess. Prove that we can choose three members of the club who play three different games amongst each other.