On a Connection Between Small Set Expansions and Modularity Clustering   in Social Networks
  In this paper we explore a connection between two seemingly different problems from two different domains: the small-set expansion problem studied in unique games conjecture, and a popular community finding approach for social networks known as the modularity clustering approach. We show that a sub-exponential time algorithm for the small-set expansion problem leads to a sub-exponential time constant factor approximation for some hard input instances of the modularity clustering problem. 
Bhaskar DasGupta and Devendra Desai
cs.SI cs.CC physics.soc-ph