SKOLR: Structured Koopman Operator Linear RNN for Time-Series Forecasting

Fuente: arXiv
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Main Authors: Zhang, Yitian, Ma, Liheng, Valkanas, Antonios, Oreshkin, Boris N., Coates, Mark
Format: Preprint
Published: 2025
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author Zhang, Yitian
Ma, Liheng
Valkanas, Antonios
Oreshkin, Boris N.
Coates, Mark
author_facet Zhang, Yitian
Ma, Liheng
Valkanas, Antonios
Oreshkin, Boris N.
Coates, Mark
contents Koopman operator theory provides a framework for nonlinear dynamical system analysis and time-series forecasting by mapping dynamics to a space of real-valued measurement functions, enabling a linear operator representation. Despite the advantage of linearity, the operator is generally infinite-dimensional. Therefore, the objective is to learn measurement functions that yield a tractable finite-dimensional Koopman operator approximation. In this work, we establish a connection between Koopman operator approximation and linear Recurrent Neural Networks (RNNs), which have recently demonstrated remarkable success in sequence modeling. We show that by considering an extended state consisting of lagged observations, we can establish an equivalence between a structured Koopman operator and linear RNN updates. Building on this connection, we present SKOLR, which integrates a learnable spectral decomposition of the input signal with a multilayer perceptron (MLP) as the measurement functions and implements a structured Koopman operator via a highly parallel linear RNN stack. Numerical experiments on various forecasting benchmarks and dynamical systems show that this streamlined, Koopman-theory-based design delivers exceptional performance.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14113
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SKOLR: Structured Koopman Operator Linear RNN for Time-Series Forecasting
Zhang, Yitian
Ma, Liheng
Valkanas, Antonios
Oreshkin, Boris N.
Coates, Mark
Machine Learning
Artificial Intelligence
Koopman operator theory provides a framework for nonlinear dynamical system analysis and time-series forecasting by mapping dynamics to a space of real-valued measurement functions, enabling a linear operator representation. Despite the advantage of linearity, the operator is generally infinite-dimensional. Therefore, the objective is to learn measurement functions that yield a tractable finite-dimensional Koopman operator approximation. In this work, we establish a connection between Koopman operator approximation and linear Recurrent Neural Networks (RNNs), which have recently demonstrated remarkable success in sequence modeling. We show that by considering an extended state consisting of lagged observations, we can establish an equivalence between a structured Koopman operator and linear RNN updates. Building on this connection, we present SKOLR, which integrates a learnable spectral decomposition of the input signal with a multilayer perceptron (MLP) as the measurement functions and implements a structured Koopman operator via a highly parallel linear RNN stack. Numerical experiments on various forecasting benchmarks and dynamical systems show that this streamlined, Koopman-theory-based design delivers exceptional performance.
title SKOLR: Structured Koopman Operator Linear RNN for Time-Series Forecasting
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2506.14113