Ah, but a cluster doesn't mean they all collaborated with each other. For example, take a look at the big one in the middle: 3 identical ones and one pretty clo

Ah, but a cluster doesn't mean they all collaborated with each other. For example, take a look at the big one in the middle: 3 identical ones and one pretty close, for a 4-person clique. Chances are that there are actually 3 connections instead of 6 - two collaborated, one shared with a friend, the other helped a friend by spelling out the pseudocode.