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- Arash A. Amini, Martin J. Wainwright
- 2008 IEEE International Symposium on Information…
- 2008

In problem of sparse principal components analysis (SPCA), the goal is to use n i.i.d. samples to estimate the leading eigenvector(s) of a p times p covariance matrix, which are known a priori to be sparse, say with at most k non-zero entries. This paper studies SPCA in the high-dimensional regime, where the model dimension p, sparsity index k, and sample… (More)

We consider the problem of community detection in a network, that is, partitioning the nodes into groups that, in some sense, reveal the structure of the network. Many algorithms have been proposed for fitting network models with communities, but most of them do not scale well to large networks, and often fail on sparse networks. We present a fast… (More)

- Arash A. Amini, Elizaveta Levina
- ArXiv
- 2014

The stochastic block model (SBM) is a popular tool for community detection in networks, but fitting it by maximum likelihood (MLE) involves an infeasible optimization problem. We propose a new semi-definite programming (SDP) solution to the problem of fitting the SBM, derived as a relaxation of the MLE. Our relaxation is tighter than other recently proposed… (More)

- Aiyou Chen, Arash A. Amini, Peter J. Bickel, Elizaveta Levina
- ArXiv
- 2012

- Arash A. Amini, XuanLong Nguyen
- IEEE Transactions on Information Theory
- 2013

We propose a probabilistic formulation that enables sequential detection of multiple change points in a network setting. We present a class of sequential detection rules for certain functionals of change points (minimum among a subset), and prove their asymptotic optimality in terms of expected detection delay. Drawing from graphical model formalism, the… (More)

- Ravindra Hegadi, Arpana Kop, +4 authors T. E. Weymouth
- 2010

Deformable models provide a promising and vigorously researched model-based approach to computer-assisted medical image analysis. The widely recognized potency of deformable models stems from their ability to segment, match, and track images of anatomic structures by exploiting (bottom-up) constraints derived from the image data together with (top-down) a… (More)

- XuanLong Nguyen, Arash A. Amini, Ram Rajagopal
- 2012 IEEE International Symposium on Information…
- 2012

We propose a probabilistic formulation that enables sequential detection of multiple change points in a network setting. We present a class of sequential detection rules for functionals of change points, and prove their asymptotic optimality properties in terms of expected detection delay time. Drawing from graphical model formalism, the sequential… (More)

Principal component analysis (PCA) is a classical method for dimension-ality reduction based on extracting the dominant eigenvectors of the sample covariance matrix. However, PCA is well known to behave poorly in the " large p, small n " setting, in which the problem dimension p is comparable to or larger than the sample size n. This paper studies PCA in… (More)

We consider the sampling problem for functional PCA (fPCA), where the simplest example is the case of taking time samples of the underlying functional components. More generally, we model the sampling operation as a continuous linear map from H to R m , where the functional components to lie in some Hilbert subspace H of L 2 , such as a reproducing kernel… (More)