Learning to Normalize on the SPD Manifold under Bures-Wasserstein Geometry

Fuente: arXiv
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Main Authors: Wang, Rui, Jin, Shaocheng, Chen, Ziheng, Luo, Xiaoqing, Wu, Xiao-Jun
Format: Preprint
Published: 2025
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_version_ 1866909560654004224
author Wang, Rui
Jin, Shaocheng
Chen, Ziheng
Luo, Xiaoqing
Wu, Xiao-Jun
author_facet Wang, Rui
Jin, Shaocheng
Chen, Ziheng
Luo, Xiaoqing
Wu, Xiao-Jun
contents Covariance matrices have proven highly effective across many scientific fields. Since these matrices lie within the Symmetric Positive Definite (SPD) manifold - a Riemannian space with intrinsic non-Euclidean geometry, the primary challenge in representation learning is to respect this underlying geometric structure. Drawing inspiration from the success of Euclidean deep learning, researchers have developed neural networks on the SPD manifolds for more faithful covariance embedding learning. A notable advancement in this area is the implementation of Riemannian batch normalization (RBN), which has been shown to improve the performance of SPD network models. Nonetheless, the Riemannian metric beneath the existing RBN might fail to effectively deal with the ill-conditioned SPD matrices (ICSM), undermining the effectiveness of RBN. In contrast, the Bures-Wasserstein metric (BWM) demonstrates superior performance for ill-conditioning. In addition, the recently introduced Generalized BWM (GBWM) parameterizes the vanilla BWM via an SPD matrix, allowing for a more nuanced representation of vibrant geometries of the SPD manifold. Therefore, we propose a novel RBN algorithm based on the GBW geometry, incorporating a learnable metric parameter. Moreover, the deformation of GBWM by matrix power is also introduced to further enhance the representational capacity of GBWM-based RBN. Experimental results on different datasets validate the effectiveness of our proposed method.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00660
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Learning to Normalize on the SPD Manifold under Bures-Wasserstein Geometry
Wang, Rui
Jin, Shaocheng
Chen, Ziheng
Luo, Xiaoqing
Wu, Xiao-Jun
Machine Learning
Covariance matrices have proven highly effective across many scientific fields. Since these matrices lie within the Symmetric Positive Definite (SPD) manifold - a Riemannian space with intrinsic non-Euclidean geometry, the primary challenge in representation learning is to respect this underlying geometric structure. Drawing inspiration from the success of Euclidean deep learning, researchers have developed neural networks on the SPD manifolds for more faithful covariance embedding learning. A notable advancement in this area is the implementation of Riemannian batch normalization (RBN), which has been shown to improve the performance of SPD network models. Nonetheless, the Riemannian metric beneath the existing RBN might fail to effectively deal with the ill-conditioned SPD matrices (ICSM), undermining the effectiveness of RBN. In contrast, the Bures-Wasserstein metric (BWM) demonstrates superior performance for ill-conditioning. In addition, the recently introduced Generalized BWM (GBWM) parameterizes the vanilla BWM via an SPD matrix, allowing for a more nuanced representation of vibrant geometries of the SPD manifold. Therefore, we propose a novel RBN algorithm based on the GBW geometry, incorporating a learnable metric parameter. Moreover, the deformation of GBWM by matrix power is also introduced to further enhance the representational capacity of GBWM-based RBN. Experimental results on different datasets validate the effectiveness of our proposed method.
title Learning to Normalize on the SPD Manifold under Bures-Wasserstein Geometry
topic Machine Learning
url https://arxiv.org/abs/2504.00660