On the Convexity and Reliability of the Bethe Free Energy Approximation

Fuente: arXiv
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Main Authors: Leisenberger, Harald, Knoll, Christian, Pernkopf, Franz
Format: Preprint
Published: 2024
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author Leisenberger, Harald
Knoll, Christian
Pernkopf, Franz
author_facet Leisenberger, Harald
Knoll, Christian
Pernkopf, Franz
contents The Bethe free energy approximation provides an effective way for relaxing NP-hard problems of probabilistic inference. However, its accuracy depends on the model parameters and particularly degrades if a phase transition in the model occurs. In this work, we analyze when the Bethe approximation is reliable and how this can be verified. We argue and show by experiment that it is mostly accurate if it is convex on a submanifold of its domain, the 'Bethe box'. For verifying its convexity, we derive two sufficient conditions that are based on the definiteness properties of the Bethe Hessian matrix: the first uses the concept of diagonal dominance, and the second decomposes the Bethe Hessian matrix into a sum of sparse matrices and characterizes the definiteness properties of the individual matrices in that sum. These theoretical results provide a simple way to estimate the critical phase transition temperature of a model. As a practical contribution we propose $\texttt{BETHE-MIN}$, a projected quasi-Newton method to efficiently find a minimum of the Bethe free energy.
format Preprint
id arxiv_https___arxiv_org_abs_2405_15514
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Convexity and Reliability of the Bethe Free Energy Approximation
Leisenberger, Harald
Knoll, Christian
Pernkopf, Franz
Machine Learning
Artificial Intelligence
The Bethe free energy approximation provides an effective way for relaxing NP-hard problems of probabilistic inference. However, its accuracy depends on the model parameters and particularly degrades if a phase transition in the model occurs. In this work, we analyze when the Bethe approximation is reliable and how this can be verified. We argue and show by experiment that it is mostly accurate if it is convex on a submanifold of its domain, the 'Bethe box'. For verifying its convexity, we derive two sufficient conditions that are based on the definiteness properties of the Bethe Hessian matrix: the first uses the concept of diagonal dominance, and the second decomposes the Bethe Hessian matrix into a sum of sparse matrices and characterizes the definiteness properties of the individual matrices in that sum. These theoretical results provide a simple way to estimate the critical phase transition temperature of a model. As a practical contribution we propose $\texttt{BETHE-MIN}$, a projected quasi-Newton method to efficiently find a minimum of the Bethe free energy.
title On the Convexity and Reliability of the Bethe Free Energy Approximation
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2405.15514