Diplomatic Distance

[WillyNilly]

In the past, when another enemy cuts through an area I "lose contact" with a race. It becomes as if I never met them and must fight through an alien in order to reconnect. I wasn't sure the distance that was required to cause me to lose connection, but I didn't care.

I'm currently in a multi-player game where I'm slightly winning (shock beyond shock), but my two human opponents are aware of this and they current share a border of one system. I'm convienced they are sharing technology, research, et cetera and so I wish to sever their relationship. I could barge and take the one border system and perhaps spread them out a few extra systems, but I'm not sure how far apart I have to drive them. Obviously if it is too far apart (5 or so systems) I'd be better off just pummeling the weakest of the two opponents.

Does anyone know what the "Diplomatic Distance is?" Most computer players are defeated so I don't have to worry about their interference.

Thanks.