DyKAF: Dynamical Kronecker Approximation of the Fisher Information Matrix for Gradient Preconditioning

Fuente: arXiv
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Main Authors: Yudin, Nikolay, Grishina, Ekaterina, Veprikov, Andrey, Beznosikov, Alexandr, Rakhuba, Maxim
Format: Preprint
Published: 2025
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author Yudin, Nikolay
Grishina, Ekaterina
Veprikov, Andrey
Beznosikov, Alexandr
Rakhuba, Maxim
author_facet Yudin, Nikolay
Grishina, Ekaterina
Veprikov, Andrey
Beznosikov, Alexandr
Rakhuba, Maxim
contents Recently, optimizers that explicitly treat weights as matrices, rather than flattened vectors, have demonstrated their effectiveness. This perspective naturally leads to structured approximations of the Fisher matrix as preconditioners, where the matrix view induces a Kronecker-factorized form that enables memory-efficient representation. However, constructing such approximations both efficiently and accurately remains an open challenge, since obtaining the optimal factorization is resource-intensive and practical methods therefore rely on heuristic design choices. In this work, we introduce a novel approach that leverages projector-splitting integrators to construct effective preconditioners. Our optimizer, DyKAF (Dynamical Kronecker Approximation of the Fisher Matrix), consistently improves the Fisher matrix approximation quality. Experiments on large language model pre-training and fine-tuning demonstrate that DyKAF outperforms existing optimizers across a range of evaluation metrics.
format Preprint
id arxiv_https___arxiv_org_abs_2511_06477
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle DyKAF: Dynamical Kronecker Approximation of the Fisher Information Matrix for Gradient Preconditioning
Yudin, Nikolay
Grishina, Ekaterina
Veprikov, Andrey
Beznosikov, Alexandr
Rakhuba, Maxim
Machine Learning
Numerical Analysis
Optimization and Control
68T07, 65F55, 15A18
Recently, optimizers that explicitly treat weights as matrices, rather than flattened vectors, have demonstrated their effectiveness. This perspective naturally leads to structured approximations of the Fisher matrix as preconditioners, where the matrix view induces a Kronecker-factorized form that enables memory-efficient representation. However, constructing such approximations both efficiently and accurately remains an open challenge, since obtaining the optimal factorization is resource-intensive and practical methods therefore rely on heuristic design choices. In this work, we introduce a novel approach that leverages projector-splitting integrators to construct effective preconditioners. Our optimizer, DyKAF (Dynamical Kronecker Approximation of the Fisher Matrix), consistently improves the Fisher matrix approximation quality. Experiments on large language model pre-training and fine-tuning demonstrate that DyKAF outperforms existing optimizers across a range of evaluation metrics.
title DyKAF: Dynamical Kronecker Approximation of the Fisher Information Matrix for Gradient Preconditioning
topic Machine Learning
Numerical Analysis
Optimization and Control
68T07, 65F55, 15A18
url https://arxiv.org/abs/2511.06477