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  Barry Wellman

   S.D. Clark Professor of Sociology, FRSC               NetLab Director
   Department of Sociology                  725 Spadina Avenue, Room 388
   University of Toronto   Toronto Canada M5S 2J4   twitter:barrywellman             fax:+1-416-978-3963
   Updating history:

Role-based similarity in directed networks , arXiv

Abstract: The widespread relevance of increasingly complex networks 
requires methods to extract meaningful coarse-grained representations of 
such systems. For undirected graphs, standard community detection methods 
use criteria largely based on density of connections to provide such 
representations. We propose a method for grouping nodes in directed 
networks based on the role of the nodes in the network, understood in 
terms of patterns of incoming and outgoing flows. The role groupings are 
obtained through the clustering of a similarity matrix, formed by the 
distances between feature vectors that contain the number of in and out 
paths of all lengths for each node. Hence nodes operating in a similar 
flow environment are grouped together although they may not themselves be 
densely connected. Our method, which includes a scale factor that reveals 
robust groupings based on increasingly global structure, provides an 
alternative criterion to uncover structure in networks where there is an 
implicit flow transfer in the system. We illustrate its application to a 
variety of data from ecology, world trade and cellular metabolism.

* [27] Role-based similarity in directed networks, Kathryn Cooper, 
Mauricio Barahona, 2010/12/13, arXiv:1012.2726

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