Simplex-to-Euclidean Bijection for Conjugate and Calibrated Multiclass Gaussian Process

Fuente: arXiv
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Main Authors: Williams, Bernardo, Tetali, Harsha Vardhan, Klami, Arto, Hartmann, Marcelo
Format: Preprint
Published: 2026
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author Williams, Bernardo
Tetali, Harsha Vardhan
Klami, Arto
Hartmann, Marcelo
author_facet Williams, Bernardo
Tetali, Harsha Vardhan
Klami, Arto
Hartmann, Marcelo
contents We propose a conjugate and calibrated Gaussian process (GP) model for multi-class classification by exploiting the geometry of the probability simplex. Our approach uses Aitchison geometry to map simplex-valued class probabilities to an unconstrained Euclidean representation, turning classification into a GP regression problem with fewer latent dimensions than standard multi-class GP classifiers. This yields conjugate inference and reliable predictive probabilities without relying on distributional approximations in the model construction. The method is compatible with standard sparse GP regression techniques, enabling scalable inference on larger datasets. Empirical results show well-calibrated and competitive performance across synthetic and real-world datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16621
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Simplex-to-Euclidean Bijection for Conjugate and Calibrated Multiclass Gaussian Process
Williams, Bernardo
Tetali, Harsha Vardhan
Klami, Arto
Hartmann, Marcelo
Machine Learning
We propose a conjugate and calibrated Gaussian process (GP) model for multi-class classification by exploiting the geometry of the probability simplex. Our approach uses Aitchison geometry to map simplex-valued class probabilities to an unconstrained Euclidean representation, turning classification into a GP regression problem with fewer latent dimensions than standard multi-class GP classifiers. This yields conjugate inference and reliable predictive probabilities without relying on distributional approximations in the model construction. The method is compatible with standard sparse GP regression techniques, enabling scalable inference on larger datasets. Empirical results show well-calibrated and competitive performance across synthetic and real-world datasets.
title Simplex-to-Euclidean Bijection for Conjugate and Calibrated Multiclass Gaussian Process
topic Machine Learning
url https://arxiv.org/abs/2603.16621