D.N. Phan, H.A. Le Thi, T. Pham Dinh, Sparse Covariance Matrix Estimation by DCA-Based Algorithms.

Abstract: This letter proposes a novel approach using the l0-norm regularization for the sparse covariance matrix estimation (SCME) problem. The objective function of SCME problem is composed of a nonconvex part and the l0-term, which is discontinuous and difficult to tackle. Appropriate DC (difference of convex functions) approximations of l0-norm are used that result in approximation SCME problems that are still nonconvex. DC programming and DCA (DC algorithm), powerful tools in nonconvex programming framework, are investigated. Two DC formulations are proposed and corresponding DCA schemes developed. Two applications of the SCME problem that are considered are classification via sparse quadratic discriminant analysis and portfolio optimization. A careful empirical experiment is performed through simulated and real data sets to study the performance of the proposed algorithms. Numerical results showed their efficiency and their superiority compared with seven state-of-the-art methods. 

 

Citation: Duy Nhat Phan, Hoai An Le Thi, Tao Pham Dinh, Sparse Covariance Matrix Estimation by DCA-Based Algorithms. Neural Computation, Volume 29, Issue 11, pp. 3040-3077, November 2017.

 

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