Approximate source conditions in Tikhonov–Phillips regularization and consequences for inverse problems with multiplication operators

B Hofmann - Mathematical Methods in the Applied Sciences, 2006 - Wiley Online Library
The object of this paper is threefold. First, we investigate in a Hilbert space setting the utility
of approximate source conditions in the method of Tikhonov–Phillips regularization for linear …

Curious ill-posedness phenomena in the composition of non-compact linear operators in Hilbert spaces

S Kindermann, B Hofmann - Journal of Inverse and Ill-posed …, 2024 - degruyter.com
We consider the composition of operators with non-closed range in Hilbert spaces and how
the nature of ill-posedness is affected by their composition. Specifically, we study the …

The degree of ill-posedness of composite linear ill-posed problems with focus on the impact of the non-compact Hausdorff moment operator

B Hofmann, P Mathé - arXiv preprint arXiv:2111.01036, 2021 - arxiv.org
We consider compact composite linear operators in Hilbert space, where the composition is
given by some compact operator followed by some non-compact one possessing a non …

A unified concept of the degree of ill-posedness for compact and non-compact linear operators in Hilbert spaces under the auspices of the spectral theorem

F Werner, B Hofmann - arXiv preprint arXiv:2408.01148, 2024 - arxiv.org
Covering ill-posed problems with compact and non-compact operators regarding the degree
of ill-posedness is a never ending story written by many authors in the inverse problems …

Mathematical analysis of the 1D model and reconstruction schemes for magnetic particle imaging

W Erb, A Weinmann, M Ahlborg, C Brandt… - Inverse …, 2018 - iopscience.iop.org
Magnetic particle imaging (MPI) is a promising new in vivo medical imaging modality in
which distributions of super-paramagnetic nanoparticles are tracked based on their …

Curious ill-posedness phenomena in the composition of non-compact linear operators

S Kindermann, B Hofmann - arXiv preprint arXiv:2401.14701, 2024 - arxiv.org
We consider the composition of operators with non-closed range in Hilbert spaces and how
the nature of ill-posedness is affected by their composition. Specifically, we study the\mbox …

Approximate source conditions in Tikhonov regularization‐new analytical results and some numerical studies

B Hofmann, D Düvelmeyer… - … Modelling and Analysis, 2006 - Taylor & Francis
We present some new ideas and results for finding convergence rates in Tikhonov
regularization for ill‐posed linear inverse problems with compact and non‐compact forward …

Regularized differential evolution for a blind phase retrieval problem in ultrashort laser pulse characterization

D Gerth, E Escoto, G Steinmeyer… - Review of Scientific …, 2019 - pubs.aip.org
Obtaining the temporal shape of an ultrashort laser pulse using the method of dispersion
scan entails solving a nonlinear inverse problem, a challenging prospect on its own, yet still …

On the type of ill-posedness of generalized Hilbert matrices and related operators

S Kindermann - Numerical Functional Analysis and Optimization, 2024 - Taylor & Francis
We consider infinite-dimensional generalized Hilbert matrices of the form H i, j= didjxi+ xj,
where di are nonnegative weights and xi are pairwise distinct positive numbers. We state …

A note on numerical singular values of compositions with non-compact operators

D Gerth - arXiv preprint arXiv:2201.13185, 2022 - arxiv.org
Linear non-compact operators are difficult to study because they do not exist in the finite
dimensional world. Recently, Math\'{e} and Hofmann studied the singular values of the …