MathDB

7

Part of 1997 Tuymaada Olympiad

Problems(1)

boys and girls visit the rink

Source: Tuymaada 1997 p7

4/28/2019
It is known that every student of the class for Sunday once visited the rink, and every boy met there with every girl. Prove that there was a point in time when all the boys, or all the girls of the class were simultaneously on the rink.
combinatorics