Natural Riemannian gradient for learning functional tensor networks

Fuente: arXiv
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Autori principali: Klug, Nikolas, Ulbrich, Michael, Uschmajew, André, Willner, Marius
Natura: Preprint
Pubblicazione: 2026
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author Klug, Nikolas
Ulbrich, Michael
Uschmajew, André
Willner, Marius
author_facet Klug, Nikolas
Ulbrich, Michael
Uschmajew, André
Willner, Marius
contents We consider machine learning tasks with low-rank functional tree tensor networks (TTN) as the learning model. While in the case of least-squares regression, low-rank functional TTNs can be efficiently optimized using alternating optimization, this is not directly possible in other problems, such as multinomial logistic regression. We propose a natural Riemannian gradient descent type approach applicable to arbitrary losses which is based on the natural gradient by Amari. In particular, the search direction obtained by the natural gradient is independent of the choice of basis of the underlying functional tensor product space. Our framework applies to both the factorized and manifold-based approach for representing the functional TTN. For practical application, we propose a hierarchy of efficient approximations to the true natural Riemannian gradient for computing the updates in the parameter space. Numerical experiments confirm our theoretical findings on common classification datasets and show that using natural Riemannian gradient descent for learning considerably improves convergence behavior when compared to standard Riemannian gradient methods.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09263
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Natural Riemannian gradient for learning functional tensor networks
Klug, Nikolas
Ulbrich, Michael
Uschmajew, André
Willner, Marius
Optimization and Control
Machine Learning
Numerical Analysis
We consider machine learning tasks with low-rank functional tree tensor networks (TTN) as the learning model. While in the case of least-squares regression, low-rank functional TTNs can be efficiently optimized using alternating optimization, this is not directly possible in other problems, such as multinomial logistic regression. We propose a natural Riemannian gradient descent type approach applicable to arbitrary losses which is based on the natural gradient by Amari. In particular, the search direction obtained by the natural gradient is independent of the choice of basis of the underlying functional tensor product space. Our framework applies to both the factorized and manifold-based approach for representing the functional TTN. For practical application, we propose a hierarchy of efficient approximations to the true natural Riemannian gradient for computing the updates in the parameter space. Numerical experiments confirm our theoretical findings on common classification datasets and show that using natural Riemannian gradient descent for learning considerably improves convergence behavior when compared to standard Riemannian gradient methods.
title Natural Riemannian gradient for learning functional tensor networks
topic Optimization and Control
Machine Learning
Numerical Analysis
url https://arxiv.org/abs/2604.09263