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Adaptive Fourier Decomposition-guided Neural Operator Design for Inverse PDE Problems
Proceedings of the 42nd Conference on Uncertainty in Artificial Intelligence, PMLR 337:6467-6491, 2026.
Abstract
Inverse problems, which are generally ill-posed, aim to identify the unknown parameters of a physical system from the observations of its output. A large class of inverse problems for partial differential equations (PDEs) are only well-defined as mappings from operators to functions. However, existing operator learning frameworks either do not explicitly account for the underlying operator space or solve the inverse problems in a {Hilbert} space. Meanwhile, it has been shown that a Banach space setting for the parameter space would be closer to reality for a wide range of problems. Driven by this, we introduce AFDONet-inv, a novel neural operator solver whose design is rigorously guided by adaptive {Fourier} decomposition (AFD) theory, to solve inverse problems for PDEs in a Banach space. Each component of AFDONet-inv’s architecture, including primal and dual nets, latent-to-RKBS (reproducing kernel Banach space) network, and dynamic convolutional kernel network (CKN), has a corresponding component in the AFD operation in Banach space. This way, AFDONet-inv is mathematically explainable and grounded in the AFD theory and possesses several desirable properties. Extensive experiments demonstrate that AFDONet-inv outperforms state-of-the-art inverse {PDE} solvers in terms of solution accuracy.