On the Weight Dynamics of Deep Normalized Networks

Fuente: arXiv
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Main Authors: Mehmeti-Göpel, Christian H. X. Ali, Wand, Michael
Format: Preprint
Published: 2023
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author Mehmeti-Göpel, Christian H. X. Ali
Wand, Michael
author_facet Mehmeti-Göpel, Christian H. X. Ali
Wand, Michael
contents Recent studies have shown that high disparities in effective learning rates (ELRs) across layers in deep neural networks can negatively affect trainability. We formalize how these disparities evolve over time by modeling weight dynamics (evolution of expected gradient and weight norms) of networks with normalization layers, predicting the evolution of layer-wise ELR ratios. We prove that when training with any constant learning rate, ELR ratios converge to 1, despite initial gradient explosion. We identify a ``critical learning rate" beyond which ELR disparities widen, which only depends on current ELRs. To validate our findings, we devise a hyper-parameter-free warm-up method that successfully minimizes ELR spread quickly in theory and practice. Our experiments link ELR spread with trainability, a relationship that is most evident in very deep networks with significant gradient magnitude excursions.
format Preprint
id arxiv_https___arxiv_org_abs_2306_00700
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the Weight Dynamics of Deep Normalized Networks
Mehmeti-Göpel, Christian H. X. Ali
Wand, Michael
Machine Learning
Artificial Intelligence
Recent studies have shown that high disparities in effective learning rates (ELRs) across layers in deep neural networks can negatively affect trainability. We formalize how these disparities evolve over time by modeling weight dynamics (evolution of expected gradient and weight norms) of networks with normalization layers, predicting the evolution of layer-wise ELR ratios. We prove that when training with any constant learning rate, ELR ratios converge to 1, despite initial gradient explosion. We identify a ``critical learning rate" beyond which ELR disparities widen, which only depends on current ELRs. To validate our findings, we devise a hyper-parameter-free warm-up method that successfully minimizes ELR spread quickly in theory and practice. Our experiments link ELR spread with trainability, a relationship that is most evident in very deep networks with significant gradient magnitude excursions.
title On the Weight Dynamics of Deep Normalized Networks
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2306.00700