From Quasirandom graphs to Graph Limits and Graphlets
  We generalize the notion of quasirandom which concerns a class of equivalent properties that random graphs satisfy. We show that the convergence of a graph sequence under the spectral distance is equivalent to the convergence using the (normalized) cut distance. The resulting graph limit is called graphlets. We then consider several families of graphlets and, in particular, we characterize graphlets with low ranks for both dense and sparse graphs. 
Fan Chung
math.CO math.SP