Soft quasi-Newton: Guaranteed positive definiteness by relaxing the secant constraint

Fuente: arXiv
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Autores principales: Berglund, Erik, Zhang, Jiaojiao, Johansson, Mikael
Formato: Preprint
Publicado: 2024
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author Berglund, Erik
Zhang, Jiaojiao
Johansson, Mikael
author_facet Berglund, Erik
Zhang, Jiaojiao
Johansson, Mikael
contents We propose a novel algorithm, termed soft quasi-Newton (soft QN), for optimization in the presence of bounded noise. Traditional quasi-Newton algorithms are vulnerable to such perturbations. To develop a more robust quasi-Newton method, we replace the secant condition in the matrix optimization problem for the Hessian update with a penalty term in its objective and derive a closed-form update formula. A key feature of our approach is its ability to maintain positive definiteness of the Hessian inverse approximation. Furthermore, we establish the following properties of soft QN: it recovers the BFGS method under specific limits, it treats positive and negative curvature equally, and it is scale invariant. Collectively, these features enhance the efficacy of soft QN in noisy environments. For strongly convex objective functions and Hessian approximations obtained using soft QN, we develop an algorithm that exhibits linear convergence toward a neighborhood of the optimal solution, even if gradient and function evaluations are subject to bounded perturbations. Through numerical experiments, we demonstrate superior performance of soft QN compared to state-of-the-art methods in various scenarios.
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id arxiv_https___arxiv_org_abs_2403_02448
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Soft quasi-Newton: Guaranteed positive definiteness by relaxing the secant constraint
Berglund, Erik
Zhang, Jiaojiao
Johansson, Mikael
Optimization and Control
90C53
We propose a novel algorithm, termed soft quasi-Newton (soft QN), for optimization in the presence of bounded noise. Traditional quasi-Newton algorithms are vulnerable to such perturbations. To develop a more robust quasi-Newton method, we replace the secant condition in the matrix optimization problem for the Hessian update with a penalty term in its objective and derive a closed-form update formula. A key feature of our approach is its ability to maintain positive definiteness of the Hessian inverse approximation. Furthermore, we establish the following properties of soft QN: it recovers the BFGS method under specific limits, it treats positive and negative curvature equally, and it is scale invariant. Collectively, these features enhance the efficacy of soft QN in noisy environments. For strongly convex objective functions and Hessian approximations obtained using soft QN, we develop an algorithm that exhibits linear convergence toward a neighborhood of the optimal solution, even if gradient and function evaluations are subject to bounded perturbations. Through numerical experiments, we demonstrate superior performance of soft QN compared to state-of-the-art methods in various scenarios.
title Soft quasi-Newton: Guaranteed positive definiteness by relaxing the secant constraint
topic Optimization and Control
90C53
url https://arxiv.org/abs/2403.02448