00:01
So we have a computer network of seven computers.
00:05
So i'll just draw them as little dots.
00:12
We've got one, two, three, four, five, six, and seven.
00:18
I'll just call them by the numbers.
00:20
So this is computer number one, computer number two, et cetera, et cetera.
00:23
So we want to show that there are at least two computers in the network that are directly connected to the same number of computers.
00:29
So i'm going to call n .i the number of computers that computer i is linked to.
00:50
Then it says in the question that every computer is directly connected to at least one of the computers.
00:56
So we know that ni is bigger than are equal to one for all i...