Exterior-Point Optimization for Sparse and Low-Rank Optimization

Many problems of substantial current interest in machine learning, statistics, and data science can be formulated as sparse and low-rank optimization problems. In this paper, we present the nonconvex exterior-point optimization solver (NExOS)—a first-order algorithm tailored to sparse and low-rank o...

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Published in:Journal of optimization theory and applications Vol. 202; no. 2; pp. 795 - 833
Main Authors: Das Gupta, Shuvomoy, Stellato, Bartolomeo, Van Parys, Bart P. G.
Format: Journal Article
Language:English
Published: New York Springer US 01.08.2024
Springer Nature B.V
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ISSN:0022-3239, 1573-2878
Online Access:Get full text
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Summary:Many problems of substantial current interest in machine learning, statistics, and data science can be formulated as sparse and low-rank optimization problems. In this paper, we present the nonconvex exterior-point optimization solver (NExOS)—a first-order algorithm tailored to sparse and low-rank optimization problems. We consider the problem of minimizing a convex function over a nonconvex constraint set, where the set can be decomposed as the intersection of a compact convex set and a nonconvex set involving sparse or low-rank constraints. Unlike the convex relaxation approaches, NExOS finds a locally optimal point of the original problem by solving a sequence of penalized problems with strictly decreasing penalty parameters by exploiting the nonconvex geometry. NExOS solves each penalized problem by applying a first-order algorithm, which converges linearly to a local minimum of the corresponding penalized formulation under regularity conditions. Furthermore, the local minima of the penalized problems converge to a local minimum of the original problem as the penalty parameter goes to zero. We then implement and test NExOS on many instances from a wide variety of sparse and low-rank optimization problems, empirically demonstrating that our algorithm outperforms specialized methods.
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ISSN:0022-3239
1573-2878
DOI:10.1007/s10957-024-02448-9