On the convergence of proximal gradient methods for convex simple bilevel optimization

Fuente: arXiv
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Autores principales: Latafat, Puya, Themelis, Andreas, Villa, Silvia, Patrinos, Panagiotis
Formato: Preprint
Publicado: 2023
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author Latafat, Puya
Themelis, Andreas
Villa, Silvia
Patrinos, Panagiotis
author_facet Latafat, Puya
Themelis, Andreas
Villa, Silvia
Patrinos, Panagiotis
contents This paper studies proximal gradient iterations for solving simple bilevel optimization problems where both the upper and the lower level cost functions are split as the sum of differentiable and (possibly nonsmooth) proximable functions. We develop a novel convergence recipe for iteration varying stepsizes that relies on Barzilai-Borwein type local estimates for the differentiable terms. Leveraging the convergence recipe, under global Lipschitz gradient continuity, we establish convergence for a nonadaptive stepsize sequence, without requiring any strong convexity or linesearch. In the locally Lipschitz differentiable setting, we develop an adaptive linesearch method that introduces a systematic adaptive scheme enabling large and nonmonotonic stepsize sequences while being insensitive to the choice of hyperparameters and initialization. Numerical simulations are provided showcasing favorable convergence speed of our methods.
format Preprint
id arxiv_https___arxiv_org_abs_2305_03559
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the convergence of proximal gradient methods for convex simple bilevel optimization
Latafat, Puya
Themelis, Andreas
Villa, Silvia
Patrinos, Panagiotis
Optimization and Control
65K05, 90C06, 90C25, 90C30
This paper studies proximal gradient iterations for solving simple bilevel optimization problems where both the upper and the lower level cost functions are split as the sum of differentiable and (possibly nonsmooth) proximable functions. We develop a novel convergence recipe for iteration varying stepsizes that relies on Barzilai-Borwein type local estimates for the differentiable terms. Leveraging the convergence recipe, under global Lipschitz gradient continuity, we establish convergence for a nonadaptive stepsize sequence, without requiring any strong convexity or linesearch. In the locally Lipschitz differentiable setting, we develop an adaptive linesearch method that introduces a systematic adaptive scheme enabling large and nonmonotonic stepsize sequences while being insensitive to the choice of hyperparameters and initialization. Numerical simulations are provided showcasing favorable convergence speed of our methods.
title On the convergence of proximal gradient methods for convex simple bilevel optimization
topic Optimization and Control
65K05, 90C06, 90C25, 90C30
url https://arxiv.org/abs/2305.03559