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Bibliographic Details
Main Authors: Massion, Bastien, Makhlouf, Roy, Massart, Estelle
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2606.00344
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author Massion, Bastien
Makhlouf, Roy
Massart, Estelle
author_facet Massion, Bastien
Makhlouf, Roy
Massart, Estelle
contents Neural collapse is a structural property of the last-hidden-layer activations in neural network classification models, when trained beyond a zero classification error. In this work, we explore the role of label encoding in neural collapse by relying on the unrestricted feature model with mean squared error training loss. We demonstrate that, for one-hot encoded labels and balanced data, the uncentered mean features associated with each class transition from a simplex equiangular tight frame to an orthogonal frame when increasing the bias regularization coefficient associated with the final classifier. These structures are reminiscent of the orthogonal frame structure of one-hot encoded labels. For any arbitrary encoding, we also show that the final classifier's bias aims at centering the labels, compensating for the discrepancy between the global mean of the labels and the origin. We further discuss the role of the encoding in other neural collapse properties.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00344
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The role of class encoding in neural collapse
Massion, Bastien
Makhlouf, Roy
Massart, Estelle
Machine Learning
Neural collapse is a structural property of the last-hidden-layer activations in neural network classification models, when trained beyond a zero classification error. In this work, we explore the role of label encoding in neural collapse by relying on the unrestricted feature model with mean squared error training loss. We demonstrate that, for one-hot encoded labels and balanced data, the uncentered mean features associated with each class transition from a simplex equiangular tight frame to an orthogonal frame when increasing the bias regularization coefficient associated with the final classifier. These structures are reminiscent of the orthogonal frame structure of one-hot encoded labels. For any arbitrary encoding, we also show that the final classifier's bias aims at centering the labels, compensating for the discrepancy between the global mean of the labels and the origin. We further discuss the role of the encoding in other neural collapse properties.
title The role of class encoding in neural collapse
topic Machine Learning
url https://arxiv.org/abs/2606.00344