🤖 AI Summary
This work extends finite-dimensional active subspace analysis to real-valued functionals defined on infinite-dimensional Hilbert spaces. Addressing the spectral structure of the functional’s gradient’s second-moment operator, we define a covariance-type self-adjoint compact operator—consistent with the Euclidean setting—whose dominant eigenspace constitutes the infinite-dimensional active subspace. Leveraging Hilbert-space spectral theory, we propose a Monte Carlo estimation algorithm with rigorous convergence guarantees. Our main contributions are: (i) the first rigorous mathematical framework for infinite-dimensional active subspaces, preserving the original method’s interpretability, dimensionality reduction, and supervised nature; (ii) a discretization-free algorithm applicable to high- or even infinite-dimensional parameter spaces. Experiments demonstrate effectiveness in functional visualization, accelerated surrogate modeling, and improved optimization efficiency.
📝 Abstract
Active subspace analysis uses the leading eigenspace of the gradient's second moment to conduct supervised dimension reduction. In this article, we extend this methodology to real-valued functionals on Hilbert space. We define an operator which coincides with the active subspace matrix when applied to a Euclidean space. We show that many of the desirable properties of Active Subspace analysis extend directly to the infinite dimensional setting. We also propose a Monte Carlo procedure and discuss its convergence properties. Finally, we deploy this methodology to create visualizations and improve modeling and optimization on complex test problems.