MathDB

2

Part of 1990 Rioplatense Mathematical Olympiad, Level 3

Problems(1)

no of people meeting odd number of others is even

Source: I - Rioplatense 1990 L3 P2

9/19/2022
Some of the people attending a meeting greet each other. Let nn be the number of people who greet an odd number of people. Prove that nn is even.
combinatoricsnumber theory