A convergence framework for energy minimisation of linear self-adjoint elliptic PDEs in nonlinear approximation spaces

Fuente: arXiv
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Autores principales: Magueresse, Alexandre, Badia, Santiago
Formato: Preprint
Publicado: 2025
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author Magueresse, Alexandre
Badia, Santiago
author_facet Magueresse, Alexandre
Badia, Santiago
contents Recent years have seen the emergence of nonlinear methods for solving partial differential equations (PDEs), such as physics-informed neural networks (PINNs). While these approaches often perform well in practice, their theoretical analysis remains limited, especially regarding convergence guarantees. This work develops a general optimisation framework for energy minimisation problems arising from linear self-adjoint elliptic PDEs, formulated over nonlinear but analytically tractable approximation spaces. The framework accommodates a natural split between linear and nonlinear parameters and supports hybrid optimisation strategies: linear variables are updated via linear solves or steepest descent, while nonlinear variables are handled using constrained projected descent. We establish both local and global convergence of the resulting algorithm under modular structural assumptions on the discrete energy functional, including differentiability, boundedness, regularity, and directional convexity. These assumptions are stated in an abstract form, allowing the framework to apply to a broad class of nonlinear approximation manifolds. In a companion paper [Magueresse, Badia (2025, arXiv:2508.17705)], we introduce a concrete instance of such a space based on overlapping free-knot tensor-product B-splines, which satisfies the required assumptions and enables geometrically adaptive solvers with rigorous convergence guarantees.
format Preprint
id arxiv_https___arxiv_org_abs_2508_17687
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A convergence framework for energy minimisation of linear self-adjoint elliptic PDEs in nonlinear approximation spaces
Magueresse, Alexandre
Badia, Santiago
Numerical Analysis
65N50, 65N12, 90C26
G.1.2; G.1.6; G.1.8
Recent years have seen the emergence of nonlinear methods for solving partial differential equations (PDEs), such as physics-informed neural networks (PINNs). While these approaches often perform well in practice, their theoretical analysis remains limited, especially regarding convergence guarantees. This work develops a general optimisation framework for energy minimisation problems arising from linear self-adjoint elliptic PDEs, formulated over nonlinear but analytically tractable approximation spaces. The framework accommodates a natural split between linear and nonlinear parameters and supports hybrid optimisation strategies: linear variables are updated via linear solves or steepest descent, while nonlinear variables are handled using constrained projected descent. We establish both local and global convergence of the resulting algorithm under modular structural assumptions on the discrete energy functional, including differentiability, boundedness, regularity, and directional convexity. These assumptions are stated in an abstract form, allowing the framework to apply to a broad class of nonlinear approximation manifolds. In a companion paper [Magueresse, Badia (2025, arXiv:2508.17705)], we introduce a concrete instance of such a space based on overlapping free-knot tensor-product B-splines, which satisfies the required assumptions and enables geometrically adaptive solvers with rigorous convergence guarantees.
title A convergence framework for energy minimisation of linear self-adjoint elliptic PDEs in nonlinear approximation spaces
topic Numerical Analysis
65N50, 65N12, 90C26
G.1.2; G.1.6; G.1.8
url https://arxiv.org/abs/2508.17687