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June 2015 Robust and computationally feasible community detection in the presence of arbitrary outlier nodes
T. Tony Cai, Xiaodong Li
Ann. Statist. 43(3): 1027-1059 (June 2015). DOI: 10.1214/14-AOS1290


Community detection, which aims to cluster $N$ nodes in a given graph into $r$ distinct groups based on the observed undirected edges, is an important problem in network data analysis. In this paper, the popular stochastic block model (SBM) is extended to the generalized stochastic block model (GSBM) that allows for adversarial outlier nodes, which are connected with the other nodes in the graph in an arbitrary way. Under this model, we introduce a procedure using convex optimization followed by $k$-means algorithm with $k=r$.

Both theoretical and numerical properties of the method are analyzed. A theoretical guarantee is given for the procedure to accurately detect the communities with small misclassification rate under the setting where the number of clusters can grow with $N$. This theoretical result admits to the best-known result in the literature of computationally feasible community detection in SBM without outliers. Numerical results show that our method is both computationally fast and robust to different kinds of outliers, while some popular computationally fast community detection algorithms, such as spectral clustering applied to adjacency matrices or graph Laplacians, may fail to retrieve the major clusters due to a small portion of outliers. We apply a slight modification of our method to a political blogs data set, showing that our method is competent in practice and comparable to existing computationally feasible methods in the literature. To the best of the authors’ knowledge, our result is the first in the literature in terms of clustering communities with fast growing numbers under the GSBM where a portion of arbitrary outlier nodes exist.


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T. Tony Cai. Xiaodong Li. "Robust and computationally feasible community detection in the presence of arbitrary outlier nodes." Ann. Statist. 43 (3) 1027 - 1059, June 2015.


Received: 1 April 2014; Revised: 1 November 2014; Published: June 2015
First available in Project Euclid: 15 May 2015

zbMATH: 1328.62381
MathSciNet: MR3346696
Digital Object Identifier: 10.1214/14-AOS1290

Primary: 62H30 , 91C20

Keywords: $k$-means clustering , dual certificate , Robust community detection , SDP relaxation

Rights: Copyright © 2015 Institute of Mathematical Statistics


Vol.43 • No. 3 • June 2015
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