TOT 339 1992 Autumn O J1 101 chess players in tournaments
Source:
June 10, 2024
combinatorics
Problem Statement
There are chess players who participated in several tournaments. There was no tournament in which all of them participated. Each pair of these players met exactly once during these tournaments. Prove that one of them participated in no less than tournaments. (Assume that each pair of participants in each tournament plays each other once in that tournament).(A Andjans, Riga)