A Comparison of Variational Bounds for the Information Bottleneck Functional

In this short note, we relate the variational bounds proposed in Alemi et al. (2017) and Fischer (2020) for the information bottleneck (IB) and the conditional entropy bottleneck (CEB) functional, respectively. Although the two functionals were shown to be equivalent, it was empirically observed tha...

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Main Authors: Bernhard C. Geiger, Ian S. Fischer
Format: Article
Language:English
Published: MDPI AG 2020-10-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/22/11/1229
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author Bernhard C. Geiger
Ian S. Fischer
author_facet Bernhard C. Geiger
Ian S. Fischer
author_sort Bernhard C. Geiger
collection DOAJ
description In this short note, we relate the variational bounds proposed in Alemi et al. (2017) and Fischer (2020) for the information bottleneck (IB) and the conditional entropy bottleneck (CEB) functional, respectively. Although the two functionals were shown to be equivalent, it was empirically observed that optimizing bounds on the CEB functional achieves better generalization performance and adversarial robustness than optimizing those on the IB functional. This work tries to shed light on this issue by showing that, in the most general setting, no ordering can be established between these variational bounds, while such an ordering can be enforced by restricting the feasible sets over which the optimizations take place. The absence of such an ordering in the general setup suggests that the variational bound on the CEB functional is either more amenable to optimization or a relevant cost function for optimization in its own regard, i.e., without justification from the IB or CEB functionals.
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spelling doaj.art-d380c722a5ec43aeb062966a846a443f2023-11-20T18:56:54ZengMDPI AGEntropy1099-43002020-10-012211122910.3390/e22111229A Comparison of Variational Bounds for the Information Bottleneck FunctionalBernhard C. Geiger0Ian S. Fischer1Know-Center GmbH, Inffeldgasse 13/6, 8010 Graz, AustriaGoogle Research, Mountain View, CA 94043, USAIn this short note, we relate the variational bounds proposed in Alemi et al. (2017) and Fischer (2020) for the information bottleneck (IB) and the conditional entropy bottleneck (CEB) functional, respectively. Although the two functionals were shown to be equivalent, it was empirically observed that optimizing bounds on the CEB functional achieves better generalization performance and adversarial robustness than optimizing those on the IB functional. This work tries to shed light on this issue by showing that, in the most general setting, no ordering can be established between these variational bounds, while such an ordering can be enforced by restricting the feasible sets over which the optimizations take place. The absence of such an ordering in the general setup suggests that the variational bound on the CEB functional is either more amenable to optimization or a relevant cost function for optimization in its own regard, i.e., without justification from the IB or CEB functionals.https://www.mdpi.com/1099-4300/22/11/1229information bottleneckdeep learningneural networks
spellingShingle Bernhard C. Geiger
Ian S. Fischer
A Comparison of Variational Bounds for the Information Bottleneck Functional
Entropy
information bottleneck
deep learning
neural networks
title A Comparison of Variational Bounds for the Information Bottleneck Functional
title_full A Comparison of Variational Bounds for the Information Bottleneck Functional
title_fullStr A Comparison of Variational Bounds for the Information Bottleneck Functional
title_full_unstemmed A Comparison of Variational Bounds for the Information Bottleneck Functional
title_short A Comparison of Variational Bounds for the Information Bottleneck Functional
title_sort comparison of variational bounds for the information bottleneck functional
topic information bottleneck
deep learning
neural networks
url https://www.mdpi.com/1099-4300/22/11/1229
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