Adaptive proximal gradient methods are universal without approximation

Fuente: arXiv
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Main Authors: Oikonomidis, Konstantinos A., Laude, Emanuel, Latafat, Puya, Themelis, Andreas, Patrinos, Panagiotis
Format: Preprint
Published: 2024
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author Oikonomidis, Konstantinos A.
Laude, Emanuel
Latafat, Puya
Themelis, Andreas
Patrinos, Panagiotis
author_facet Oikonomidis, Konstantinos A.
Laude, Emanuel
Latafat, Puya
Themelis, Andreas
Patrinos, Panagiotis
contents We show that adaptive proximal gradient methods for convex problems are not restricted to traditional Lipschitzian assumptions. Our analysis reveals that a class of linesearch-free methods is still convergent under mere local Hölder gradient continuity, covering in particular continuously differentiable semi-algebraic functions. To mitigate the lack of local Lipschitz continuity, popular approaches revolve around $\varepsilon$-oracles and/or linesearch procedures. In contrast, we exploit plain Hölder inequalities not entailing any approximation, all while retaining the linesearch-free nature of adaptive schemes. Furthermore, we prove full sequence convergence without prior knowledge of local Hölder constants nor of the order of Hölder continuity. Numerical experiments make comparisons with baseline methods on diverse tasks from machine learning covering both the locally and the globally Hölder setting.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06271
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Adaptive proximal gradient methods are universal without approximation
Oikonomidis, Konstantinos A.
Laude, Emanuel
Latafat, Puya
Themelis, Andreas
Patrinos, Panagiotis
Optimization and Control
Machine Learning
65K05, 90C06, 90C25, 90C30, 90C47
We show that adaptive proximal gradient methods for convex problems are not restricted to traditional Lipschitzian assumptions. Our analysis reveals that a class of linesearch-free methods is still convergent under mere local Hölder gradient continuity, covering in particular continuously differentiable semi-algebraic functions. To mitigate the lack of local Lipschitz continuity, popular approaches revolve around $\varepsilon$-oracles and/or linesearch procedures. In contrast, we exploit plain Hölder inequalities not entailing any approximation, all while retaining the linesearch-free nature of adaptive schemes. Furthermore, we prove full sequence convergence without prior knowledge of local Hölder constants nor of the order of Hölder continuity. Numerical experiments make comparisons with baseline methods on diverse tasks from machine learning covering both the locally and the globally Hölder setting.
title Adaptive proximal gradient methods are universal without approximation
topic Optimization and Control
Machine Learning
65K05, 90C06, 90C25, 90C30, 90C47
url https://arxiv.org/abs/2402.06271