High dimensional analysis reveals conservative sharpening and a stochastic edge of stability

Fuente: arXiv
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Autores principales: Agarwala, Atish, Pennington, Jeffrey
Formato: Preprint
Publicado: 2024
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author Agarwala, Atish
Pennington, Jeffrey
author_facet Agarwala, Atish
Pennington, Jeffrey
contents Recent empirical and theoretical work has shown that the dynamics of the large eigenvalues of the training loss Hessian have some remarkably robust features across models and datasets in the full batch regime. There is often an early period of progressive sharpening where the large eigenvalues increase, followed by stabilization at a predictable value known as the edge of stability. Previous work showed that in the stochastic setting, the eigenvalues increase more slowly - a phenomenon we call conservative sharpening. We provide a theoretical analysis of a simple high-dimensional model which shows the origin of this slowdown. We also show that there is an alternative stochastic edge of stability which arises at small batch size that is sensitive to the trace of the Neural Tangent Kernel rather than the large Hessian eigenvalues. We conduct an experimental study which highlights the qualitative differences from the full batch phenomenology, and suggests that controlling the stochastic edge of stability can help optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2404_19261
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle High dimensional analysis reveals conservative sharpening and a stochastic edge of stability
Agarwala, Atish
Pennington, Jeffrey
Machine Learning
Optimization and Control
Statistics Theory
Data Analysis, Statistics and Probability
Recent empirical and theoretical work has shown that the dynamics of the large eigenvalues of the training loss Hessian have some remarkably robust features across models and datasets in the full batch regime. There is often an early period of progressive sharpening where the large eigenvalues increase, followed by stabilization at a predictable value known as the edge of stability. Previous work showed that in the stochastic setting, the eigenvalues increase more slowly - a phenomenon we call conservative sharpening. We provide a theoretical analysis of a simple high-dimensional model which shows the origin of this slowdown. We also show that there is an alternative stochastic edge of stability which arises at small batch size that is sensitive to the trace of the Neural Tangent Kernel rather than the large Hessian eigenvalues. We conduct an experimental study which highlights the qualitative differences from the full batch phenomenology, and suggests that controlling the stochastic edge of stability can help optimization.
title High dimensional analysis reveals conservative sharpening and a stochastic edge of stability
topic Machine Learning
Optimization and Control
Statistics Theory
Data Analysis, Statistics and Probability
url https://arxiv.org/abs/2404.19261