Minimaxity and Admissibility of Bayesian Neural Networks

Fuente: arXiv
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Main Authors: Coulson, Daniel Andrew, Wells, Martin T.
Format: Preprint
Published: 2026
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_version_ 1866913007662006272
author Coulson, Daniel Andrew
Wells, Martin T.
author_facet Coulson, Daniel Andrew
Wells, Martin T.
contents Bayesian neural networks (BNNs) offer a natural probabilistic formulation for inference in deep learning models. Despite their popularity, their optimality has received limited attention through the lens of statistical decision theory. In this paper, we study decision rules induced by deep, fully connected feedforward ReLU BNNs in the normal location model under quadratic loss. We show that, for fixed prior scales, the induced Bayes decision rule is not minimax. We then propose a hyperprior on the effective output variance of the BNN prior that yields a superharmonic square-root marginal density, establishing that the resulting decision rule is simultaneously admissible and minimax. We further extend these results from the quadratic loss setting to the predictive density estimation problem with Kullback--Leibler loss. Finally, we validate our theoretical findings numerically through simulation.
format Preprint
id arxiv_https___arxiv_org_abs_2604_04673
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Minimaxity and Admissibility of Bayesian Neural Networks
Coulson, Daniel Andrew
Wells, Martin T.
Statistics Theory
Machine Learning
Primary 62C10, 62C15, 62C20, 62M45, secondary 62A15, 62F15
Bayesian neural networks (BNNs) offer a natural probabilistic formulation for inference in deep learning models. Despite their popularity, their optimality has received limited attention through the lens of statistical decision theory. In this paper, we study decision rules induced by deep, fully connected feedforward ReLU BNNs in the normal location model under quadratic loss. We show that, for fixed prior scales, the induced Bayes decision rule is not minimax. We then propose a hyperprior on the effective output variance of the BNN prior that yields a superharmonic square-root marginal density, establishing that the resulting decision rule is simultaneously admissible and minimax. We further extend these results from the quadratic loss setting to the predictive density estimation problem with Kullback--Leibler loss. Finally, we validate our theoretical findings numerically through simulation.
title Minimaxity and Admissibility of Bayesian Neural Networks
topic Statistics Theory
Machine Learning
Primary 62C10, 62C15, 62C20, 62M45, secondary 62A15, 62F15
url https://arxiv.org/abs/2604.04673