Adaptive Open-Loop Step-Sizes for Accelerated Convergence Rates of the Frank-Wolfe Algorithm

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Autori principali: Wirth, Elias, Peña, Javier, Pokutta, Sebastian
Natura: Preprint
Pubblicazione: 2025
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author Wirth, Elias
Peña, Javier
Pokutta, Sebastian
author_facet Wirth, Elias
Peña, Javier
Pokutta, Sebastian
contents Recent work has shown that in certain settings, the Frank-Wolfe algorithm (FW) with open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ for a fixed parameter $\ell \in \mathbb{N},\, \ell \geq 2$, attains a convergence rate faster than the traditional $O(t^{-1})$ rate. In particular, when a strong growth property holds, the convergence rate attainable with open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ is $O(t^{-\ell})$. In this setting there is no single value of the parameter $\ell$ that prevails as superior. This paper shows that FW with log-adaptive open-loop step-sizes $η_t = \frac{2+\log(t+1)}{t+2+\log(t+1)}$ attains a convergence rate that is at least as fast as that attainable with fixed-parameter open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ for any value of $\ell \in \mathbb{N},\,\ell\geq 2$. To establish our main convergence results, we extend our previous affine-invariant accelerated convergence results for FW to more general open-loop step-sizes of the form $η_t = g(t)/(t+g(t))$, where $g:\mathbb{N}\to\mathbb{R}_{\geq 0}$ is any non-decreasing function such that the sequence of step-sizes $(η_t)$ is non-increasing. This covers in particular the fixed-parameter case by choosing $g(t) = \ell$ and the log-adaptive case by choosing $g(t) = 2+ \log(t+1)$. To facilitate adoption of log-adaptive open-loop step-sizes, we have incorporated this rule into the {\tt FrankWolfe.jl} software package.
format Preprint
id arxiv_https___arxiv_org_abs_2505_09886
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Adaptive Open-Loop Step-Sizes for Accelerated Convergence Rates of the Frank-Wolfe Algorithm
Wirth, Elias
Peña, Javier
Pokutta, Sebastian
Optimization and Control
Recent work has shown that in certain settings, the Frank-Wolfe algorithm (FW) with open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ for a fixed parameter $\ell \in \mathbb{N},\, \ell \geq 2$, attains a convergence rate faster than the traditional $O(t^{-1})$ rate. In particular, when a strong growth property holds, the convergence rate attainable with open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ is $O(t^{-\ell})$. In this setting there is no single value of the parameter $\ell$ that prevails as superior. This paper shows that FW with log-adaptive open-loop step-sizes $η_t = \frac{2+\log(t+1)}{t+2+\log(t+1)}$ attains a convergence rate that is at least as fast as that attainable with fixed-parameter open-loop step-sizes $η_t = \frac{\ell}{t+\ell}$ for any value of $\ell \in \mathbb{N},\,\ell\geq 2$. To establish our main convergence results, we extend our previous affine-invariant accelerated convergence results for FW to more general open-loop step-sizes of the form $η_t = g(t)/(t+g(t))$, where $g:\mathbb{N}\to\mathbb{R}_{\geq 0}$ is any non-decreasing function such that the sequence of step-sizes $(η_t)$ is non-increasing. This covers in particular the fixed-parameter case by choosing $g(t) = \ell$ and the log-adaptive case by choosing $g(t) = 2+ \log(t+1)$. To facilitate adoption of log-adaptive open-loop step-sizes, we have incorporated this rule into the {\tt FrankWolfe.jl} software package.
title Adaptive Open-Loop Step-Sizes for Accelerated Convergence Rates of the Frank-Wolfe Algorithm
topic Optimization and Control
url https://arxiv.org/abs/2505.09886