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Re: [igraph] Definition of Modularity
From: |
Tamás Nepusz |
Subject: |
Re: [igraph] Definition of Modularity |
Date: |
Wed, 13 Feb 2013 22:46:39 +0100 |
> 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.