I am interested in the combinatorial properties of social networks as graphs. People have looked at things such as the distribution of the degrees, the clustering coefficient and the compressibility of these graphs. One basic question is: Are these graphs typically good expander graphs?
Has anyone checked, say, the facebook graph's spectral gap? Or the spectral gap of other large real-world networks? I am hoping that someone can point me in the right direction to learn about this topic.