Two persons with the same number of acquaintance in a party

There are $n$ persons attending a party. Prove that there are two persons who have the same number of acquaintance among the people attending the party.

Answer

Answers can be viewed only if
  1. The questioner was satisfied and accepted the answer, or
  2. The answer was disputed, but the judge evaluated it as 100% correct.
View the answer
Erdos Erdos
4.6K
The answer is accepted.
Join Matchmaticians Affiliate Marketing Program to earn up to 50% commission on every question your affiliated users ask or answer.