Relative entropy minimization over Hilbert spaces via Robbins-Monro

One way of getting insight into non-Gaussian measures is to first obtain good Gaussian approximations. These best fit Gaussians can then provide a sense of the mean and variance of the distribution of interest. They can also be used to accelerate sampling algorithms. This begs the question of how on...

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Main Authors: Gideon Simpson, Daniel Watkins
Format: Article
Language:English
Published: AIMS Press 2019-03-01
Series:AIMS Mathematics
Subjects:
Online Access:https://www.aimspress.com/article/10.3934/math.2019.3.359/fulltext.html
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author Gideon Simpson
Daniel Watkins
author_facet Gideon Simpson
Daniel Watkins
author_sort Gideon Simpson
collection DOAJ
description One way of getting insight into non-Gaussian measures is to first obtain good Gaussian approximations. These best fit Gaussians can then provide a sense of the mean and variance of the distribution of interest. They can also be used to accelerate sampling algorithms. This begs the question of how one should measure optimality, and how to then obtain this optimal approximation. Here, we consider the problem of minimizing the distance between a family of Gaussians and the target measure with respect to relative entropy, or Kullback-Leibler divergence. As we are interested in applications in the infinite dimensional setting, it is desirable to have convergent algorithms that are well posed on abstract Hilbert spaces. We examine this minimization problem by seeking roots of the first variation of relative entropy, taken with respect to the mean of the Gaussian, leaving the covariance fixed. We prove the convergence of Robbins-Monro type root finding algorithms in this context, highlighting the assumptions necessary for convergence to relative entropy minimizers. Numerical examples are included to illustrate the algorithms.
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spelling doaj.art-f06fb259fc6941e08c9f879a8f392aa12022-12-21T18:44:18ZengAIMS PressAIMS Mathematics2473-69882019-03-014335938310.3934/math.2019.3.359Relative entropy minimization over Hilbert spaces via Robbins-MonroGideon Simpson0Daniel Watkins11 Department of Mathematics, Drexel University, Philadelphia, PA 19104, USA2 Department of Ocean, Earth, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USAOne way of getting insight into non-Gaussian measures is to first obtain good Gaussian approximations. These best fit Gaussians can then provide a sense of the mean and variance of the distribution of interest. They can also be used to accelerate sampling algorithms. This begs the question of how one should measure optimality, and how to then obtain this optimal approximation. Here, we consider the problem of minimizing the distance between a family of Gaussians and the target measure with respect to relative entropy, or Kullback-Leibler divergence. As we are interested in applications in the infinite dimensional setting, it is desirable to have convergent algorithms that are well posed on abstract Hilbert spaces. We examine this minimization problem by seeking roots of the first variation of relative entropy, taken with respect to the mean of the Gaussian, leaving the covariance fixed. We prove the convergence of Robbins-Monro type root finding algorithms in this context, highlighting the assumptions necessary for convergence to relative entropy minimizers. Numerical examples are included to illustrate the algorithms.https://www.aimspress.com/article/10.3934/math.2019.3.359/fulltext.htmlRobbins-Monrorelative entropyHilbert space
spellingShingle Gideon Simpson
Daniel Watkins
Relative entropy minimization over Hilbert spaces via Robbins-Monro
AIMS Mathematics
Robbins-Monro
relative entropy
Hilbert space
title Relative entropy minimization over Hilbert spaces via Robbins-Monro
title_full Relative entropy minimization over Hilbert spaces via Robbins-Monro
title_fullStr Relative entropy minimization over Hilbert spaces via Robbins-Monro
title_full_unstemmed Relative entropy minimization over Hilbert spaces via Robbins-Monro
title_short Relative entropy minimization over Hilbert spaces via Robbins-Monro
title_sort relative entropy minimization over hilbert spaces via robbins monro
topic Robbins-Monro
relative entropy
Hilbert space
url https://www.aimspress.com/article/10.3934/math.2019.3.359/fulltext.html
work_keys_str_mv AT gideonsimpson relativeentropyminimizationoverhilbertspacesviarobbinsmonro
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