Convex optimization techniques for fitting sparse Gaussian graphical models

  • Authors:
  • Onureena Banerjee;Laurent El Ghaoui;Alexandre d'Aspremont;Georges Natsoulis

  • Affiliations:
  • UC Berkeley, Berkeley, CA;UC Berkeley, Berkeley, CA;Princeton University, Princeton, NJ;Iconix Pharmaceuticals, Mountain View, CA

  • Venue:
  • ICML '06 Proceedings of the 23rd international conference on Machine learning
  • Year:
  • 2006

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Abstract

We consider the problem of fitting a large-scale covariance matrix to multivariate Gaussian data in such a way that the inverse is sparse, thus providing model selection. Beginning with a dense empirical covariance matrix, we solve a maximum likelihood problem with an l1-norm penalty term added to encourage sparsity in the inverse. For models with tens of nodes, the resulting problem can be solved using standard interior-point algorithms for convex optimization, but these methods scale poorly with problem size. We present two new algorithms aimed at solving problems with a thousand nodes. The first, based on Nesterov's first-order algorithm, yields a rigorous complexity estimate for the problem, with a much better dependence on problem size than interior-point methods. Our second algorithm uses block coordinate descent, updating row/columns of the covariance matrix sequentially. Experiments with genomic data show that our method is able to uncover biologically interpretable connections among genes.