Equilibrated-flux residual certification for verified existence and outputs

Fuente: arXiv
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Main Author: Ishizaka, Hiroki
Format: Preprint
Published: 2026
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author Ishizaka, Hiroki
author_facet Ishizaka, Hiroki
contents We present a post-processing certification workflow for nonlinear elliptic boundary value problems that upgrades a standard finite element computation to a rigorous existence and output certificate. For a given approximate discrete state, we verify existence and local uniqueness of a weak solution in a computable neighbourhood via a Newton--Kantorovich argument based on three certified ingredients: a guaranteed dual-norm residual bound, a computable lower bound for the stability constant of the linearised operator, and a Lipschitz bound for the derivative on the verification ball. The residual bound is obtained by an equilibrated-flux reconstruction exploiting an explicit relation between nonconforming and mixed formulations, yielding $H(\mathrm{div})$-conforming fluxes without local mixed solves. The stability ingredient follows from a computable coercivity lower bound for the linearisation. An admissible verification radius is selected by a simple bracketing--bisection search, justified for an affine Lipschitz model. Once the verification ball is certified, we derive guaranteed enclosures for quantities of interest using computable variation bounds; an adjoint-based correction, in the spirit of goal-oriented error estimation, tightens these intervals while retaining full rigour. Numerical experiments for semilinear diffusion--reaction models show that the certificates are informative and that the adjoint enhancement substantially reduces enclosure widths.
format Preprint
id arxiv_https___arxiv_org_abs_2602_01636
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Equilibrated-flux residual certification for verified existence and outputs
Ishizaka, Hiroki
Numerical Analysis
We present a post-processing certification workflow for nonlinear elliptic boundary value problems that upgrades a standard finite element computation to a rigorous existence and output certificate. For a given approximate discrete state, we verify existence and local uniqueness of a weak solution in a computable neighbourhood via a Newton--Kantorovich argument based on three certified ingredients: a guaranteed dual-norm residual bound, a computable lower bound for the stability constant of the linearised operator, and a Lipschitz bound for the derivative on the verification ball. The residual bound is obtained by an equilibrated-flux reconstruction exploiting an explicit relation between nonconforming and mixed formulations, yielding $H(\mathrm{div})$-conforming fluxes without local mixed solves. The stability ingredient follows from a computable coercivity lower bound for the linearisation. An admissible verification radius is selected by a simple bracketing--bisection search, justified for an affine Lipschitz model. Once the verification ball is certified, we derive guaranteed enclosures for quantities of interest using computable variation bounds; an adjoint-based correction, in the spirit of goal-oriented error estimation, tightens these intervals while retaining full rigour. Numerical experiments for semilinear diffusion--reaction models show that the certificates are informative and that the adjoint enhancement substantially reduces enclosure widths.
title Equilibrated-flux residual certification for verified existence and outputs
topic Numerical Analysis
url https://arxiv.org/abs/2602.01636