2023 employees in the office
Source: 2023 NZMO - New Zealand Maths Olympiad Round 1 p1
September 2, 2023
combinatorics
Problem Statement
There are 2023 employees in the office, each of them knowing exactly of the others. For any pair of employees they either both know each other or both don’t know each other. Prove that we can find employees each of them knowing all others.