Understanding Gradient Descent through the Training Jacobian

Fuente: arXiv
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Autores principales: Belrose, Nora, Scherlis, Adam
Formato: Preprint
Publicado: 2024
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author Belrose, Nora
Scherlis, Adam
author_facet Belrose, Nora
Scherlis, Adam
contents We examine the geometry of neural network training using the Jacobian of trained network parameters with respect to their initial values. Our analysis reveals low-dimensional structure in the training process which is dependent on the input data but largely independent of the labels. We find that the singular value spectrum of the Jacobian matrix consists of three distinctive regions: a "chaotic" region of values orders of magnitude greater than one, a large "bulk" region of values extremely close to one, and a "stable" region of values less than one. Along each bulk direction, the left and right singular vectors are nearly identical, indicating that perturbations to the initialization are carried through training almost unchanged. These perturbations have virtually no effect on the network's output in-distribution, yet do have an effect far out-of-distribution. While the Jacobian applies only locally around a single initialization, we find substantial overlap in bulk subspaces for different random seeds. Our code is available at https://github.com/EleutherAI/training-jacobian
format Preprint
id arxiv_https___arxiv_org_abs_2412_07003
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Understanding Gradient Descent through the Training Jacobian
Belrose, Nora
Scherlis, Adam
Machine Learning
We examine the geometry of neural network training using the Jacobian of trained network parameters with respect to their initial values. Our analysis reveals low-dimensional structure in the training process which is dependent on the input data but largely independent of the labels. We find that the singular value spectrum of the Jacobian matrix consists of three distinctive regions: a "chaotic" region of values orders of magnitude greater than one, a large "bulk" region of values extremely close to one, and a "stable" region of values less than one. Along each bulk direction, the left and right singular vectors are nearly identical, indicating that perturbations to the initialization are carried through training almost unchanged. These perturbations have virtually no effect on the network's output in-distribution, yet do have an effect far out-of-distribution. While the Jacobian applies only locally around a single initialization, we find substantial overlap in bulk subspaces for different random seeds. Our code is available at https://github.com/EleutherAI/training-jacobian
title Understanding Gradient Descent through the Training Jacobian
topic Machine Learning
url https://arxiv.org/abs/2412.07003