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Main Authors: Zhou, Yuhao, Xu, Jintao, Li, Bingrui, Bao, Chenglong, Ding, Chao, Zhu, Jun
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.04799
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author Zhou, Yuhao
Xu, Jintao
Li, Bingrui
Bao, Chenglong
Ding, Chao
Zhu, Jun
author_facet Zhou, Yuhao
Xu, Jintao
Li, Bingrui
Bao, Chenglong
Ding, Chao
Zhu, Jun
contents Finding an $ε$-stationary point of a nonconvex function with a Lipschitz continuous Hessian is a central problem in optimization. Regularized Newton methods are a classical tool and have been studied extensively, yet they still face a trade-off between global and local convergence. Whether a parameter-free algorithm of this type can simultaneously achieve optimal global complexity and quadratic local convergence remains an open question. To bridge this long-standing gap, we propose a new class of regularizers constructed from the current and previous gradients, and leverage the conjugate gradient approach with a negative curvature monitor to solve the regularized Newton equation. The proposed algorithm is adaptive, requiring no prior knowledge of the Hessian Lipschitz constant, and achieves a global complexity of $O(ε^{-3/2})$ in terms of the second-order oracle calls, and $\tilde{O}(ε^{-7/4})$ for Hessian-vector products, respectively. When the iterates converge to a point where the Hessian is positive definite, the method exhibits quadratic local convergence. Preliminary numerical results, including training the physics-informed neural networks, illustrate the competitiveness of our algorithm.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04799
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Regularized Newton Method for Nonconvex Optimization with Global and Local Complexity Guarantees
Zhou, Yuhao
Xu, Jintao
Li, Bingrui
Bao, Chenglong
Ding, Chao
Zhu, Jun
Optimization and Control
Machine Learning
Finding an $ε$-stationary point of a nonconvex function with a Lipschitz continuous Hessian is a central problem in optimization. Regularized Newton methods are a classical tool and have been studied extensively, yet they still face a trade-off between global and local convergence. Whether a parameter-free algorithm of this type can simultaneously achieve optimal global complexity and quadratic local convergence remains an open question. To bridge this long-standing gap, we propose a new class of regularizers constructed from the current and previous gradients, and leverage the conjugate gradient approach with a negative curvature monitor to solve the regularized Newton equation. The proposed algorithm is adaptive, requiring no prior knowledge of the Hessian Lipschitz constant, and achieves a global complexity of $O(ε^{-3/2})$ in terms of the second-order oracle calls, and $\tilde{O}(ε^{-7/4})$ for Hessian-vector products, respectively. When the iterates converge to a point where the Hessian is positive definite, the method exhibits quadratic local convergence. Preliminary numerical results, including training the physics-informed neural networks, illustrate the competitiveness of our algorithm.
title A Regularized Newton Method for Nonconvex Optimization with Global and Local Complexity Guarantees
topic Optimization and Control
Machine Learning
url https://arxiv.org/abs/2502.04799