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Main Authors: Muşat, Andreea-Alexandra, Boumal, Nicolas
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.02782
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author Muşat, Andreea-Alexandra
Boumal, Nicolas
author_facet Muşat, Andreea-Alexandra
Boumal, Nicolas
contents Optimization algorithms are unlikely to converge to strict saddle points. Proofs to that effect rely on the Center-Stable Manifold Theorem (CSMT), casting algorithms as dynamical systems: $x_{k+1} = g_k(x_k)$. In its standard form, the CSMT is limited to autonomous systems (the maps $g_k$ are all the same). To study algorithms such as gradient descent with non-constant step-size schedules, we need a non-autonomous CSMT. There are a few, but they are unable to handle, for example, vanishing step sizes. To cover such scenarios, we establish a new Center-Stable Set Theorem (CSST) for non-autonomous systems. We use it to prove saddle avoidance for gradient descent (Euclidean and Riemannian) and for the proximal point method, without assuming Lipschitz gradients or isolated saddles, and allowing vanishing step sizes.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02782
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A non-autonomous center-stable set theorem for saddle avoidance in optimization
Muşat, Andreea-Alexandra
Boumal, Nicolas
Optimization and Control
Numerical Analysis
Dynamical Systems
90C30 (Primary) 65K05, 37C75, 58K05 (Secondary)
Optimization algorithms are unlikely to converge to strict saddle points. Proofs to that effect rely on the Center-Stable Manifold Theorem (CSMT), casting algorithms as dynamical systems: $x_{k+1} = g_k(x_k)$. In its standard form, the CSMT is limited to autonomous systems (the maps $g_k$ are all the same). To study algorithms such as gradient descent with non-constant step-size schedules, we need a non-autonomous CSMT. There are a few, but they are unable to handle, for example, vanishing step sizes. To cover such scenarios, we establish a new Center-Stable Set Theorem (CSST) for non-autonomous systems. We use it to prove saddle avoidance for gradient descent (Euclidean and Riemannian) and for the proximal point method, without assuming Lipschitz gradients or isolated saddles, and allowing vanishing step sizes.
title A non-autonomous center-stable set theorem for saddle avoidance in optimization
topic Optimization and Control
Numerical Analysis
Dynamical Systems
90C30 (Primary) 65K05, 37C75, 58K05 (Secondary)
url https://arxiv.org/abs/2603.02782