The basic problem is that FB models the social graph with a rigid, undirected graph when in fact we live in multiple, constantly-evolving, weighted graphs of so

The basic problem is that FB models the social graph with a rigid, undirected graph when in fact we live in multiple, constantly-evolving, weighted graphs of social connections. The newsfeed-ranking algorithm, privacy controls, friend lists, and latest groups incarnation are all simply hacks to try to shoehorn it's flawed social schema into what we actually experience in the real world.