MathDB

183

Part of 1973 All Soviet Union Mathematical Olympiad

Problems(1)

ASU 183 All Soviet Union MO 1973 no 3 men have same no of acquaintances of N

Source:

7/4/2019
NN men are not acquainted each other. You need to introduce some of them to some of them in such a way, that no three men will have equal number of acquaintances. Prove that it is possible for all NN.
combinatorics