Why the enemy of my enemy is my friend.

Mathematicians and information scientists from Cornell University developed a dynamic mathematical model, that can predict the development of social relationships within a network. The paradigm behind is, that relationships drive toward stability or balance. And as long as conflicting relationships within a network exist, the system is in-stabile and thus: in development. Testing the model for several initial situations, the outcome was always the same: either all parties within a network became friends or two opposing blocks with strong internal relationships emerged. Both states are stable in a mathematical sense. The model was tested on historic data and showed a surprising accuracy in the predicted final state. Not surprising is, that companies like Google, Yahoo and Microsoft co-financed the study.
The article is in German, and was published on Spiegel Online in January 2011. Though, nice top-level and easy to grasp introduction into the topic, and the links to the original study are provided.