Abide by the Law and Follow the Flow: Conservation Laws for Gradient Flows

Fuente: arXiv
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Hauptverfasser: Marcotte, Sibylle, Gribonval, Rémi, Peyré, Gabriel
Format: Preprint
Veröffentlicht: 2023
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author Marcotte, Sibylle
Gribonval, Rémi
Peyré, Gabriel
author_facet Marcotte, Sibylle
Gribonval, Rémi
Peyré, Gabriel
contents Understanding the geometric properties of gradient descent dynamics is a key ingredient in deciphering the recent success of very large machine learning models. A striking observation is that trained over-parameterized models retain some properties of the optimization initialization. This "implicit bias" is believed to be responsible for some favorable properties of the trained models and could explain their good generalization properties. The purpose of this article is threefold. First, we rigorously expose the definition and basic properties of "conservation laws", that define quantities conserved during gradient flows of a given model (e.g. of a ReLU network with a given architecture) with any training data and any loss. Then we explain how to find the maximal number of independent conservation laws by performing finite-dimensional algebraic manipulations on the Lie algebra generated by the Jacobian of the model. Finally, we provide algorithms to: a) compute a family of polynomial laws; b) compute the maximal number of (not necessarily polynomial) independent conservation laws. We provide showcase examples that we fully work out theoretically. Besides, applying the two algorithms confirms for a number of ReLU network architectures that all known laws are recovered by the algorithm, and that there are no other independent laws. Such computational tools pave the way to understanding desirable properties of optimization initialization in large machine learning models.
format Preprint
id arxiv_https___arxiv_org_abs_2307_00144
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Abide by the Law and Follow the Flow: Conservation Laws for Gradient Flows
Marcotte, Sibylle
Gribonval, Rémi
Peyré, Gabriel
Machine Learning
Optimization and Control
Understanding the geometric properties of gradient descent dynamics is a key ingredient in deciphering the recent success of very large machine learning models. A striking observation is that trained over-parameterized models retain some properties of the optimization initialization. This "implicit bias" is believed to be responsible for some favorable properties of the trained models and could explain their good generalization properties. The purpose of this article is threefold. First, we rigorously expose the definition and basic properties of "conservation laws", that define quantities conserved during gradient flows of a given model (e.g. of a ReLU network with a given architecture) with any training data and any loss. Then we explain how to find the maximal number of independent conservation laws by performing finite-dimensional algebraic manipulations on the Lie algebra generated by the Jacobian of the model. Finally, we provide algorithms to: a) compute a family of polynomial laws; b) compute the maximal number of (not necessarily polynomial) independent conservation laws. We provide showcase examples that we fully work out theoretically. Besides, applying the two algorithms confirms for a number of ReLU network architectures that all known laws are recovered by the algorithm, and that there are no other independent laws. Such computational tools pave the way to understanding desirable properties of optimization initialization in large machine learning models.
title Abide by the Law and Follow the Flow: Conservation Laws for Gradient Flows
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2307.00144