[igraph] overlapping community detection

[Sirinda Palahan]

Hi all,

I was wondering if there is any community detection algorithms that return overlapping communities where communities are just subgraphs and not cliques.
Most of overlapping community detection papers I have read so far define a community as a clique. But my networks don't contain any cliques.
I like the results I got from fast_greedy and would like to know if there is any extension of it that return overlapping clusters.
Any paper suggestion would be appreciated or a suggestion how I should modify the fast_greedy so each vertex can belong to more than one cluster.
thank you very much.

Sirinda