Hybrid Iterative Neural Low-Regularity Integrator for Nonlinear Dispersive Equations

TL;DR

HIN-LRI combines classical numerical solvers with neural operators to improve accuracy and stability in solving nonlinear dispersive PDEs, especially with rough data.

Contribution

This work introduces a hybrid neural-integrator framework that learns residual errors on top of low-regularity integrators, enhancing stability and accuracy.

Findings

HIN-LRI outperforms traditional integrators and neural surrogates on dispersive benchmarks.

The method maintains stability under spatial refinement and out-of-distribution data.

Experiments show modest online computational overhead.

Abstract

We propose HIN-LRI, a hybrid framework that augments a classical numerical solver with a neural operator trained to correct the solver's structured truncation error. A base low-regularity integrator provides a consistent first-order approximation to nonlinear dispersive PDEs, while a lightweight neural network, operating on a low-dimensional latent manifold, learns the residual defect that analytical methods cannot close. An explicit time-step scaling on the neural correction ensures that its Lipschitz contribution remains $\mathcal{O}(\tau)$, yielding a Gronwall stability factor bounded uniformly in the step size and independent of the spatial resolution. The network is trained end-to-end through a solver-in-the-loop objective that unrolls the full iteration and penalises trajectory error in a Bourgain-type norm, aligning learning with multi-step solver dynamics rather than isolated one-step targets. Under stated assumptions, the global error satisfies $C(\varepsilon_{net}+\delta)\,\tau^\gamma\ln(1/\tau)$, where $\varepsilon_{net}$ measures the network approximation quality and $\delta$ the training shortfall. Experiments on three dispersive benchmarks with rough data show that HIN-LRI improves accuracy over analytical integrators, splitting methods, and neural PDE surrogates, with stable spatial refinement, effective out-of-distribution transfer, and modest online overhead.