Guaranteed inf-sup bounds and existence verification for semilinear elliptic problems via nonconforming finite elements

Fuente: arXiv
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Main Author: Gräßle, Benedikt
Format: Preprint
Published: 2026
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author Gräßle, Benedikt
author_facet Gräßle, Benedikt
contents A Newton--Kantorovich-type argument enables the a posteriori existence verification of a unique regular root near a computed approximation, purely from computable data. This framework allows for non-selfadjoint problems and extends the existing verification theory to nonconforming discretisations. A key ingredient is a guaranteed lower bound on the continuous inf-sup constant from a quasi-optimal nonconforming discretisation that enables a novel a priori error estimator. All quantities are obtained by post-processing a single discretisation; convergence rates are proved. The theory is applied to a fourth-order formulation of the stationary two-dimensional Navier--Stokes equations and illustrated by numerical experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21887
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Guaranteed inf-sup bounds and existence verification for semilinear elliptic problems via nonconforming finite elements
Gräßle, Benedikt
Numerical Analysis
65N30, 65N12, 65N50
A Newton--Kantorovich-type argument enables the a posteriori existence verification of a unique regular root near a computed approximation, purely from computable data. This framework allows for non-selfadjoint problems and extends the existing verification theory to nonconforming discretisations. A key ingredient is a guaranteed lower bound on the continuous inf-sup constant from a quasi-optimal nonconforming discretisation that enables a novel a priori error estimator. All quantities are obtained by post-processing a single discretisation; convergence rates are proved. The theory is applied to a fourth-order formulation of the stationary two-dimensional Navier--Stokes equations and illustrated by numerical experiments.
title Guaranteed inf-sup bounds and existence verification for semilinear elliptic problems via nonconforming finite elements
topic Numerical Analysis
65N30, 65N12, 65N50
url https://arxiv.org/abs/2604.21887