Transitivity

If you get a call from a friend of a friend who needs to sleep on your couch for the night, should you do it? It depends on who the friend is and what the friend says about the person.

The same issues apply to friend-of-a-friend relationships in computer networks. Maybe the node in the middle is undependable so you don't trust any of its friends. Maybe the node in the middle is a mediocre judge of other nodes, and it gives a half hearted recommendation of some other node. How do you quantify this stuff?

In hopes of pinning down the concept somewhat, I wrote this chunky definition of transitivity in <Decent> MemeBag.