MathDB

7

Part of 2013 Ukraine Team Selection Test

Problems(1)

2013 users on social network, max friendship under conditions

Source: Ukraine TST 2013 p7

4/28/2020
20132013 users have registered on the social network "Graph". Some users are friends, and friendship in "Graph" is mutual. It is known that among network users there are no three, each of whom would be friends. Find the biggest one possible number of pairs of friends in "Graph".
combinatorics