Error bounds for particle gradient descent, and extensions of the log-Sobolev and Talagrand inequalities

Fuente: arXiv
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Auteurs principaux: Caprio, Rocco, Kuntz, Juan, Power, Samuel, Johansen, Adam M.
Format: Preprint
Publié: 2024
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author Caprio, Rocco
Kuntz, Juan
Power, Samuel
Johansen, Adam M.
author_facet Caprio, Rocco
Kuntz, Juan
Power, Samuel
Johansen, Adam M.
contents We prove non-asymptotic error bounds for particle gradient descent (PGD, Kuntz et al., 2023), a recently introduced algorithm for maximum likelihood estimation of large latent variable models obtained by discretizing a gradient flow of the free energy. We begin by showing that the flow converges exponentially fast to the free energy's minimizers for models satisfying a condition that generalizes both the log-Sobolev and the Polyak--Łojasiewicz inequalities (LSI and PŁI, respectively). We achieve this by extending a result well-known in the optimal transport literature (that the LSI implies the Talagrand inequality) and its counterpart in the optimization literature (that the PŁI implies the so-called quadratic growth condition), and applying the extension to our new setting. We also generalize the Bakry--Émery Theorem and show that the LSI/PŁI extension holds for models with strongly concave log-likelihoods. For such models, we further control PGD's discretization error and obtain the non-asymptotic error bounds. While we are motivated by the study of PGD, we believe that the inequalities and results we extend may be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2403_02004
institution arXiv
publishDate 2024
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spellingShingle Error bounds for particle gradient descent, and extensions of the log-Sobolev and Talagrand inequalities
Caprio, Rocco
Kuntz, Juan
Power, Samuel
Johansen, Adam M.
Machine Learning
Functional Analysis
Optimization and Control
Computation
We prove non-asymptotic error bounds for particle gradient descent (PGD, Kuntz et al., 2023), a recently introduced algorithm for maximum likelihood estimation of large latent variable models obtained by discretizing a gradient flow of the free energy. We begin by showing that the flow converges exponentially fast to the free energy's minimizers for models satisfying a condition that generalizes both the log-Sobolev and the Polyak--Łojasiewicz inequalities (LSI and PŁI, respectively). We achieve this by extending a result well-known in the optimal transport literature (that the LSI implies the Talagrand inequality) and its counterpart in the optimization literature (that the PŁI implies the so-called quadratic growth condition), and applying the extension to our new setting. We also generalize the Bakry--Émery Theorem and show that the LSI/PŁI extension holds for models with strongly concave log-likelihoods. For such models, we further control PGD's discretization error and obtain the non-asymptotic error bounds. While we are motivated by the study of PGD, we believe that the inequalities and results we extend may be of independent interest.
title Error bounds for particle gradient descent, and extensions of the log-Sobolev and Talagrand inequalities
topic Machine Learning
Functional Analysis
Optimization and Control
Computation
url https://arxiv.org/abs/2403.02004