Nonparametric Sparse Online Learning of the Koopman Operator

Fuente: arXiv
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Auteurs principaux: Hou, Boya, Sanjari, Sina, Dahlin, Nathan, Koppel, Alec, Bose, Subhonmesh
Format: Preprint
Publié: 2025
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author Hou, Boya
Sanjari, Sina
Dahlin, Nathan
Koppel, Alec
Bose, Subhonmesh
author_facet Hou, Boya
Sanjari, Sina
Dahlin, Nathan
Koppel, Alec
Bose, Subhonmesh
contents The Koopman operator provides a powerful framework for representing the dynamics of general nonlinear dynamical systems. Data-driven techniques to learn the Koopman operator typically assume that the chosen function space is closed under system dynamics. In this paper, we study the Koopman operator via its action on the reproducing kernel Hilbert space (RKHS), and explore the mis-specified scenario where the dynamics may escape the chosen function space. We relate the Koopman operator to the conditional mean embeddings (CME) operator and then present an operator stochastic approximation algorithm to learn the Koopman operator iteratively with control over the complexity of the representation. We provide both asymptotic and finite-time last-iterate guarantees of the online sparse learning algorithm with trajectory-based sampling with an analysis that is substantially more involved than that for finite-dimensional stochastic approximation. Numerical examples confirm the effectiveness of the proposed algorithm.
format Preprint
id arxiv_https___arxiv_org_abs_2501_16489
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Nonparametric Sparse Online Learning of the Koopman Operator
Hou, Boya
Sanjari, Sina
Dahlin, Nathan
Koppel, Alec
Bose, Subhonmesh
Machine Learning
Systems and Control
The Koopman operator provides a powerful framework for representing the dynamics of general nonlinear dynamical systems. Data-driven techniques to learn the Koopman operator typically assume that the chosen function space is closed under system dynamics. In this paper, we study the Koopman operator via its action on the reproducing kernel Hilbert space (RKHS), and explore the mis-specified scenario where the dynamics may escape the chosen function space. We relate the Koopman operator to the conditional mean embeddings (CME) operator and then present an operator stochastic approximation algorithm to learn the Koopman operator iteratively with control over the complexity of the representation. We provide both asymptotic and finite-time last-iterate guarantees of the online sparse learning algorithm with trajectory-based sampling with an analysis that is substantially more involved than that for finite-dimensional stochastic approximation. Numerical examples confirm the effectiveness of the proposed algorithm.
title Nonparametric Sparse Online Learning of the Koopman Operator
topic Machine Learning
Systems and Control
url https://arxiv.org/abs/2501.16489