Divide et Calibra: Multiclass Local Calibration via Vector Quantization

Fuente: arXiv
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Autores principales: Barbera, Cesare, Perini, Lorenzo, De Toni, Giovanni, Passerini, Andrea, Pugnana, Andrea
Formato: Preprint
Publicado: 2026
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author Barbera, Cesare
Perini, Lorenzo
De Toni, Giovanni
Passerini, Andrea
Pugnana, Andrea
author_facet Barbera, Cesare
Perini, Lorenzo
De Toni, Giovanni
Passerini, Andrea
Pugnana, Andrea
contents Accurate and well-calibrated Machine Learning (ML) models are mandatory in high-stakes settings, yet effective multiclass calibration remains challenging: global approaches assume calibration errors are homogeneous across the latent space, while local methods often rely on latent-space dimensionality reduction, which leads to information loss. To address these issues, we propose a compositional approach to multiclass calibration, where region-specific calibration maps are constructed from shared codeword-dependent factors. We instantiate this idea via Vector Quantization (VQ), which induces a structured partition of the representation space, and an indexed parameterization of Dirichlet concentrations that enables parameter sharing across regions. Our approach learns heterogeneous calibration maps that generalize well even to sparse regions of the latent space. Experiments on benchmark datasets show significant improvements in local calibration while maintaining competitive global calibration and predictive performance.
format Preprint
id arxiv_https___arxiv_org_abs_2605_21060
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Divide et Calibra: Multiclass Local Calibration via Vector Quantization
Barbera, Cesare
Perini, Lorenzo
De Toni, Giovanni
Passerini, Andrea
Pugnana, Andrea
Machine Learning
Artificial Intelligence
Accurate and well-calibrated Machine Learning (ML) models are mandatory in high-stakes settings, yet effective multiclass calibration remains challenging: global approaches assume calibration errors are homogeneous across the latent space, while local methods often rely on latent-space dimensionality reduction, which leads to information loss. To address these issues, we propose a compositional approach to multiclass calibration, where region-specific calibration maps are constructed from shared codeword-dependent factors. We instantiate this idea via Vector Quantization (VQ), which induces a structured partition of the representation space, and an indexed parameterization of Dirichlet concentrations that enables parameter sharing across regions. Our approach learns heterogeneous calibration maps that generalize well even to sparse regions of the latent space. Experiments on benchmark datasets show significant improvements in local calibration while maintaining competitive global calibration and predictive performance.
title Divide et Calibra: Multiclass Local Calibration via Vector Quantization
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.21060