Basically, I looked at each player one by one, and assumed for the sake of argument that they were mafia. So I tried to figure out who their potential teammates would be, in that scenario. In your case, considering that you targeted FE and Pokechu, and Maven targeted you, then if you are mafia, it's unlikely that any of those three would be on your team. So that's what I mean by narrowing down the pool of potential teammates.
It's just a way of looking at each player, and seeing if I can use what I know about them to figure out who they might or might not be working with. If I can narrow down a person's potential allies enough, then it can help me figure out the likelihood of them being mafia or not.
I only did this after mistakenly posting the original list I had; if not for accidentally hitting the "post" button, I would probably have worked it into something like a chart of who I think could be allied with whom, since that would have better explained the point I was trying to make.
Obviously I exclude myself from all of this, because I know I'm in the clear.