Prove that if any two people are either friends or strangers, then any group of 18 people contains either 4 mutual friends or 4 mutual strangers.
(In reply to re: No Subject
by Math Man)
Agreed, I got hung up on that bit as well. It's important to remember that the requirements for a quartet are significantly stricter than that for a trio. With a trio, only three relationships of matching status are needed (confined to three people, of course). But for a quartet, we have a total of *six* relationships that must match among the four people: 1 to 2, 1 to 3, 1 to 4, 2 to 3, 2 to 4, and 3 to 4.
Posted by Caleb
on 2012-08-07 10:58:20