Abstract In [1], we proved that the inverse of the stiffness matrix of an h-version finite element
method (FEM) applied to scalar second order elliptic boundary value problems can be …

We consider the preconditioned conjugate gradient method (PCG) with optimal
preconditioner in the frame of the boundary element method for elliptic first-kind integral …

We consider fractional Sobolev spaces $ H^\theta $, $\theta\in (0, 1) $, on 2D domains and $
H^ 1$-conforming discretizations by globally continuous piecewise polynomials on a mesh …

We define and analyze (local) multilevel diagonal preconditioners for isogeometric
boundary elements on locally refined meshes in two dimensions. Hypersingular and weakly …

We consider fractional Sobolev spaces H θ, θ∈(0, 1), on 2D domains and H 1-conforming
discretizations by globally continuous piecewise polynomials on a mesh consisting of shape …

We consider fractional Sobolev spaces H θ (Γ), θ∈[0, 1] on a 2D surface Γ. We show that
functions in H θ (Γ) can be decomposed into contributions with local support in a stable way …

In this thesis, we prove that the inverse of a certain type of Gram matrix can be approximated
well from the class of hierarchical matrices. The entries of a Gram matrix are determined by a …

In our previous works, we proved that the inverse of the stiffness matrix of an $ h $-version
finite element method (FEM) applied to scalar second order elliptic boundary value …

The purpose of this paper is to discuss representations of high order $ C^ 0$ finite element
spaces on simplicial meshes in any dimension. When computing with high order piecewise …

We consider the discretization of the hypersingular integral operator by the hp-version of the
Galerkin boundary element method (hp-BEM) and propose a preconditioner based on the …