Spectral Bayesian Regression on the Sphere

Fuente: arXiv
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Autor principal: Durastanti, Claudio
Formato: Preprint
Publicado: 2026
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author Durastanti, Claudio
author_facet Durastanti, Claudio
contents We develop a fully intrinsic Bayesian framework for nonparametric regression on the unit sphere based on isotropic Gaussian field priors and the harmonic structure induced by the Laplace-Beltrami operator. Under uniform random design, the regression model admits an exact diagonalization in the spherical harmonic basis, yielding a Gaussian sequence representation with frequency-dependent multiplicities. Exploiting this structure, we derive closed-form posterior distributions, optimal spectral truncation schemes, and sharp posterior contraction rates under integrated squared loss. For Gaussian priors with polynomially decaying angular power spectra, including spherical Matérn priors, we establish posterior contraction rates over Sobolev classes, which are minimax-optimal under correct prior calibration. We further show that the posterior mean admits an exact variational characterization as a geometrically intrinsic penalized least-squares estimator, equivalent to a Laplace-Beltrami smoothing spline.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20528
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Spectral Bayesian Regression on the Sphere
Durastanti, Claudio
Statistics Theory
Probability
Machine Learning
62G08, 62G20, 60G15, 58J35, 42C10
We develop a fully intrinsic Bayesian framework for nonparametric regression on the unit sphere based on isotropic Gaussian field priors and the harmonic structure induced by the Laplace-Beltrami operator. Under uniform random design, the regression model admits an exact diagonalization in the spherical harmonic basis, yielding a Gaussian sequence representation with frequency-dependent multiplicities. Exploiting this structure, we derive closed-form posterior distributions, optimal spectral truncation schemes, and sharp posterior contraction rates under integrated squared loss. For Gaussian priors with polynomially decaying angular power spectra, including spherical Matérn priors, we establish posterior contraction rates over Sobolev classes, which are minimax-optimal under correct prior calibration. We further show that the posterior mean admits an exact variational characterization as a geometrically intrinsic penalized least-squares estimator, equivalent to a Laplace-Beltrami smoothing spline.
title Spectral Bayesian Regression on the Sphere
topic Statistics Theory
Probability
Machine Learning
62G08, 62G20, 60G15, 58J35, 42C10
url https://arxiv.org/abs/2601.20528