Gradient Descent Converges Linearly to Flatter Minima than Gradient Flow in Shallow Linear Networks

Fuente: arXiv
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Autori principali: Beneventano, Pierfrancesco, Woodworth, Blake
Natura: Preprint
Pubblicazione: 2025
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author Beneventano, Pierfrancesco
Woodworth, Blake
author_facet Beneventano, Pierfrancesco
Woodworth, Blake
contents We study the gradient descent (GD) dynamics of a depth-2 linear neural network with a single input and output. We show that GD converges at an explicit linear rate to a global minimum of the training loss, even with a large stepsize -- about $2/\textrm{sharpness}$. It still converges for even larger stepsizes, but may do so very slowly. We also characterize the solution to which GD converges, which has lower norm and sharpness than the gradient flow solution. Our analysis reveals a trade off between the speed of convergence and the magnitude of implicit regularization. This sheds light on the benefits of training at the ``Edge of Stability'', which induces additional regularization by delaying convergence and may have implications for training more complex models.
format Preprint
id arxiv_https___arxiv_org_abs_2501_09137
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gradient Descent Converges Linearly to Flatter Minima than Gradient Flow in Shallow Linear Networks
Beneventano, Pierfrancesco
Woodworth, Blake
Machine Learning
Optimization and Control
We study the gradient descent (GD) dynamics of a depth-2 linear neural network with a single input and output. We show that GD converges at an explicit linear rate to a global minimum of the training loss, even with a large stepsize -- about $2/\textrm{sharpness}$. It still converges for even larger stepsizes, but may do so very slowly. We also characterize the solution to which GD converges, which has lower norm and sharpness than the gradient flow solution. Our analysis reveals a trade off between the speed of convergence and the magnitude of implicit regularization. This sheds light on the benefits of training at the ``Edge of Stability'', which induces additional regularization by delaying convergence and may have implications for training more complex models.
title Gradient Descent Converges Linearly to Flatter Minima than Gradient Flow in Shallow Linear Networks
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2501.09137