Abstract
Koopman operator theory provides a linear framework for analyzing nonlinear dynamical systems and has become a major tool for data-driven modeling. A central challenge, however, is that finite-dimensional approximations computed by methods such as extended dynamic mode decomposition (EDMD) require the dictionary to be specified a priori. Recent machine-learning approaches address this limitation by learning the dictionary from data, predominantly using artificial neural network (ANN) autoencoder architectures. Although kernel methods offer an alternative with greater interpretability and tractability for theoretical analysis, they have received little attention in this setting. We introduce extended dynamic mode decomposition with kernel-based dictionary learning (EDMD-kDL), a kernel-based method for learning finite-dimensional Koopman embeddings directly from data. The method combines ideas from collocation methods and bilevel optimization to simultaneously learn a kernel dictionary and the corresponding Koopman approximation. We evaluate EDMD-kDL against state-of-the-art ANN-based approaches on a range of numerical experiments, including global sea-surface-temperature forecasting and learning directly from video data. Across all tested settings, EDMD-kDL achieves performance comparable to or better than the ANN-based methods. Moreover, in contrast to standard kernel methods, the proposed approach is scalable to large datasets by design since the size of the required kernel matrices depends on the number of collocation points rather than the size of the training dataset.
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Publication details
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- Green open access
Cite this article
APA 7
N'konzi, J. P. N., Nüske, F., & Klus, S. (2026). Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders. https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders
MLA 9
N'konzi, Joel-Pascal Ntwali, et al. "Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders." https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders.
Chicago (author–date)
N'konzi, Joel-Pascal Ntwali, Feliks Nüske, and Stefan Klus. 2026. "Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders." https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders.
Harvard
N'konzi, J. P. N., Nüske, F. and Klus, S. (2026) 'Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders', Available at: https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders.
Vancouver
N'konzi JPN, Nüske F, Klus S. Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders. https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders
IEEE
J. P. N. N'konzi, F. Nüske, and S. Klus, "Bilevel optimization for data-driven learning of Koopman embeddings using kernel-based autoencoders," https://omanscience.com/en/articles/bilevel-optimization-for-data-driven-learning-of-koopman-embeddings-using-kernel-based-autoencoders.