collaborators

5 papers

math.AP2026

Optimal trace norms for Helmholtz problems

Benedikt Gräßle

The natural energy norm for Helmholtz problems is weighted with the wavenumber modulus and induces weighted norms on the trace spaces by minimal ext…

math.AP2026

Dirichlet-to-Neumann operator for the Helmholtz problem with general wavenumbers on the -sphere

Benedikt Gräßle, Stefan A. Sauter

This paper considers the Helmholtz problem in the exterior of a ball with Dirichlet boundary conditions and radiation conditions imposed at infinity. The differential Helmholtz ope…

math.NA2026

BEM for variable coefficient second-order problems

Benedikt Gräßle, Stefan A. Sauter

A novel boundary element method (BEM) removes the classical dependence on explicit fundamental solutions and extends quasi-optimal BEM discretisations to strongly elliptic operator…

math.NA2026

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

Benedikt Gräßle

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 framew…

math.AP2025

Stable skeleton integral equations for general coefficient Helmholtz transmission problems

Benedikt Gräßle, Ralf Hiptmair, Stefan Sauter

A novel variational formulation of layer potentials and boundary integral operators generalizes their classical construction by Green's functions, which are not explicitly availabl…