Re: [igraph] Definition of Modularity

[Tamás Nepusz]

> Thank you for explaining this for me. But I am still confused about why 
> multiply 
> m at last using  Ki/2m * Kj/2m * 2.
Because the graph is undirected, so an edge generated from vertex i to vertex j 
(which has probability Ki/2m * Kj/2m) is equivalent to an edge generated from 
vertex j to vertex i (which also has probability Ki/2m * Kj/2m). Therefore, the 
probability of generating an edge between vertex i and vertex j is Ki/2m*Kj/2m 
+ Kj/2m*Ki/2m, which is Ki/2m * Kj/2m * 2 in the end.

-- 
T.