arXiv Machine Learning

Fractional is Better: Learnable Derivative Orders in Neural Operator Learning

arXiv Machine Learning
Jun 25

A Zeroth-Order Deep Learning Method for Fully Nonlinear Parabolic Partial Differential Equations with Unknown Coefficients

arXiv:2606. 24999v1 Announce Type: new Abstract: High-dimensional partial differential equations (PDEs) with unknown coefficients arise widely in scientific machine learning, including continuous-time reinforcement learning, yet solving them efficiently in a data-driven way remains challenging.

By Yanwei Jia, Du Ouyang, Huy\^en Pham, Xun Yu Zhou
arXiv Machine Learning
Aug 14

Robust data-driven discovery of fractional differential equations via weak formulations and Pareto-based subset selection

arXiv:2608. 12879v1 Announce Type: new Abstract: Fractional partial differential equations describe nonlocal dynamics, but discovering them from noisy data is difficult because fractional differentiation amplifies high-frequency measurement noise and the derivative orders are unknown.

By Pongpisit Thanasutives, Yoshinobu Kawahara
arXiv Machine Learning
Oct 12

Low-Rank Kolmogorov-Arnold Generator Flows for Interpretable Operator Learning

The paper introduces KAFlow, a low‑rank Kolmogorov‑Arnold flow that learns the generator of physical operators as a compact symbol composed of univariate Kolmogorov‑Arnold functions. By fixing the gauge of these functions, integrating dynamics with exact exponential integrators, and automatically distilling closed‑form expressions, KAFlow achieves markedly lower out‑of‑distribution loss and higher precision on synthetic benchmarks, long‑horizon quantum dynamics, and variable‑order fractional operators. The method recovers operator coefficients to within 10⁻⁴ and discovers complex dispersion relations that sparse regression cannot capture.

By Minjong Cheon
arXiv Machine Learning
Sep 3

Learning Spectral-Like Mesh-Free Discretisations

The paper introduces Spectral-like Neural Discretisation (SpeND), a mesh‑free method that learns stencil weights via a neural network to approximate the modal response of a spectral operator across a specified band of wavenumbers. By projecting the network output onto the space of polynomial‑consistent weights, SpeND ensures exact consistency while minimizing dispersion and dissipation errors in a self‑supervised, physics‑agnostic manner. Experiments on disordered 2‑D node sets demonstrate that the learned fourth‑order operator matches the exact spectral response over a wider band than traditional LABFM or structured‑grid finite differences, and retains fourth‑order convergence upon refinement.

By Lucas Gerken Starepravo, Henry Broadley, Steven Lind, Jack R. C. King
arXiv Machine Learning
Oct 2

The limits of exactness: On the failure of automatic differentiation in physics-informed machine learning

The article discusses how automatic differentiation (AD) enables neural networks to compute derivatives of governing equations to machine precision, forming the backbone of physics-informed machine learning. However, the author argues that numerical exactness does not guarantee physical fidelity, as AD lacks awareness of the physical structure a solution must satisfy. The paper highlights that many physical constraints—such as convection directionality, diffusion, dispersion, conservation, thermodynamic consistency, symmetry, symplectic structure, positivity, monotonicity, and boundedness—are overlooked by AD, suggesting a need to rethink how PDE-driven neural surrogates are built.

By Ameya D. Jagtap
arXiv Machine Learning
Aug 27

StablePDENet: Enhancing Neural Operator Stability through Physics-Informed Residual-Sensitivity Regularization

The paper introduces StablePDENet, a physics-informed adversarial training framework that regularizes the residual sensitivity of neural operators to improve stability against input perturbations. The method formulates operator learning as a min–max optimization, where a physics-based projected‑gradient adversary generates perturbations and the outer objective combines the attacked physics loss with a normalized residual‑sensitivity penalty. Experiments on benchmark problems show that StablePDENet outperforms PI‑DeepONet and its adversarial variant in accuracy under adversarial attacks while maintaining competitive performance on clean data, and it also enhances generalization and highlights the distinction between model sensitivity and intrinsic operator ill‑conditioning.

By Chutian Huang, Chang Ma, Kaibo Wang, Yang Xiang