How Muon's Spectral Design Benefits Generalization: A Study on Imbalanced Data

Fuente: arXiv
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Autores principales: Vasudeva, Bhavya, Deora, Puneesh, Zhao, Yize, Sharan, Vatsal, Thrampoulidis, Christos
Formato: Preprint
Publicado: 2025
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author Vasudeva, Bhavya
Deora, Puneesh
Zhao, Yize
Sharan, Vatsal
Thrampoulidis, Christos
author_facet Vasudeva, Bhavya
Deora, Puneesh
Zhao, Yize
Sharan, Vatsal
Thrampoulidis, Christos
contents The growing adoption of spectrum-aware matrix-valued optimizers such as Muon and Shampoo in deep learning motivates a systematic study of their generalization properties and, in particular, when they might outperform competitive algorithms. We approach this question by introducing appropriate simplifying abstractions as follows: First, we use imbalanced data as a testbed. Second, we study the canonical form of such optimizers, which is Spectral Gradient Descent (SpecGD) -- each update step is $UV^T$ where $UΣV^T$ is the truncated SVD of the gradient. Third, within this framework we identify a canonical setting for which we precisely quantify when SpecGD outperforms vanilla Euclidean GD. For a Gaussian mixture data model and both linear and bilinear models, we show that unlike GD, which prioritizes learning dominant principal components of the data first, SpecGD learns all principal components of the data at equal rates. We demonstrate how this translates to a growing gap in class balanced loss favoring SpecGD early in training and further show that the gap remains consistent even when the GD counterpart uses adaptive step-sizes via normalization. By extending the analysis to deep linear models, we show that depth amplifies these effects. We empirically verify our theoretical findings on a variety of imbalanced datasets. Our experiments compare practical variants of spectral methods, like Muon and Shampoo, against their Euclidean counterparts and Adam. The results validate our findings that these spectral optimizers achieve superior generalization by promoting a more balanced learning of the data's underlying components.
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id arxiv_https___arxiv_org_abs_2510_22980
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How Muon's Spectral Design Benefits Generalization: A Study on Imbalanced Data
Vasudeva, Bhavya
Deora, Puneesh
Zhao, Yize
Sharan, Vatsal
Thrampoulidis, Christos
Machine Learning
The growing adoption of spectrum-aware matrix-valued optimizers such as Muon and Shampoo in deep learning motivates a systematic study of their generalization properties and, in particular, when they might outperform competitive algorithms. We approach this question by introducing appropriate simplifying abstractions as follows: First, we use imbalanced data as a testbed. Second, we study the canonical form of such optimizers, which is Spectral Gradient Descent (SpecGD) -- each update step is $UV^T$ where $UΣV^T$ is the truncated SVD of the gradient. Third, within this framework we identify a canonical setting for which we precisely quantify when SpecGD outperforms vanilla Euclidean GD. For a Gaussian mixture data model and both linear and bilinear models, we show that unlike GD, which prioritizes learning dominant principal components of the data first, SpecGD learns all principal components of the data at equal rates. We demonstrate how this translates to a growing gap in class balanced loss favoring SpecGD early in training and further show that the gap remains consistent even when the GD counterpart uses adaptive step-sizes via normalization. By extending the analysis to deep linear models, we show that depth amplifies these effects. We empirically verify our theoretical findings on a variety of imbalanced datasets. Our experiments compare practical variants of spectral methods, like Muon and Shampoo, against their Euclidean counterparts and Adam. The results validate our findings that these spectral optimizers achieve superior generalization by promoting a more balanced learning of the data's underlying components.
title How Muon's Spectral Design Benefits Generalization: A Study on Imbalanced Data
topic Machine Learning
url https://arxiv.org/abs/2510.22980