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Main Authors: Ribeiro, Jose Vinicius, Goncalves, Rafael Figueira, Melquiades, Fabio Luiz, Junior, Sylvio Barbon
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.02684
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author Ribeiro, Jose Vinicius
Goncalves, Rafael Figueira
Melquiades, Fabio Luiz
Junior, Sylvio Barbon
author_facet Ribeiro, Jose Vinicius
Goncalves, Rafael Figueira
Melquiades, Fabio Luiz
Junior, Sylvio Barbon
contents Spectral-based machine learning models have been increasingly deployed in chemometrics and spectroscopy, where predictive accuracy is as important as explainability. Current employed eXplainable Artificial Intelligence (XAI) methods are largely adapted from tabular or generic multivariate domains, assigning relevance to isolated spectral variables rather than to the chemically meaningful spectral zones. Widely adopted tools such as SHapley Additive exPlanations (SHAP), Permutation Feature Importance (PFI), and Variable Importance in Projection scores (VIP) were not designed for the physical continuity and high collinearity of spectral data, and their variable-level outputs require post-hoc aggregation to recover zone-level information. This study introduces the Spectral Model eXplainer (SMX), a post-hoc, global, model-agnostic XAI framework that explains spectral classifiers through expert-informed spectral zones. SMX summarizes each zone via PCA, defines quantile-based logical predicates, estimates predicate relevance with perturbation in stochastic subsamples, and aggregates bag-wise rankings in a directed weighted graph summarized by Local Reaching Centrality. A key component is threshold spectrum reconstruction, which back-projects predicate boundaries to the original spectral domain in natural measurement units, enabling direct visual comparison with measured spectra. The method was evaluated on eight real spectral datasets (six based on X-ray Fluorescence--XRF and two based on Gamma-ray Spectrometry) and one synthetic benchmark with known gr
format Preprint
id arxiv_https___arxiv_org_abs_2605_02684
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Spectral Model eXplainer: a chemically-grounded explainability framework for spectral-based machine learning models
Ribeiro, Jose Vinicius
Goncalves, Rafael Figueira
Melquiades, Fabio Luiz
Junior, Sylvio Barbon
Machine Learning
Applied Physics
Spectral-based machine learning models have been increasingly deployed in chemometrics and spectroscopy, where predictive accuracy is as important as explainability. Current employed eXplainable Artificial Intelligence (XAI) methods are largely adapted from tabular or generic multivariate domains, assigning relevance to isolated spectral variables rather than to the chemically meaningful spectral zones. Widely adopted tools such as SHapley Additive exPlanations (SHAP), Permutation Feature Importance (PFI), and Variable Importance in Projection scores (VIP) were not designed for the physical continuity and high collinearity of spectral data, and their variable-level outputs require post-hoc aggregation to recover zone-level information. This study introduces the Spectral Model eXplainer (SMX), a post-hoc, global, model-agnostic XAI framework that explains spectral classifiers through expert-informed spectral zones. SMX summarizes each zone via PCA, defines quantile-based logical predicates, estimates predicate relevance with perturbation in stochastic subsamples, and aggregates bag-wise rankings in a directed weighted graph summarized by Local Reaching Centrality. A key component is threshold spectrum reconstruction, which back-projects predicate boundaries to the original spectral domain in natural measurement units, enabling direct visual comparison with measured spectra. The method was evaluated on eight real spectral datasets (six based on X-ray Fluorescence--XRF and two based on Gamma-ray Spectrometry) and one synthetic benchmark with known gr
title Spectral Model eXplainer: a chemically-grounded explainability framework for spectral-based machine learning models
topic Machine Learning
Applied Physics
url https://arxiv.org/abs/2605.02684