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We propose, analyze, and test new iterative solvers for large-scale systems of linear algebraic equations arising from the finite element discretization of reduced optimality systems defining the finite element approximations to the…

Numerical Analysis · Mathematics 2023-12-20 Ulrich Langer , Richard Löscher , Olaf Steinbach , Huidong Yang

This work is concerned with linear inverse problems where a distributed parameter is known a priori to only take on values from a given discrete set. This property can be promoted in Tikhonov regularization with the aid of a suitable convex…

Optimization and Control · Mathematics 2018-04-19 Christian Clason , Thi Bich Tram Do

We consider the task of image reconstruction while simultaneously decomposing the reconstructed image into components with different features. A commonly used tool for this is a variational approach with an infimal convolution of…

Numerical Analysis · Mathematics 2025-04-16 Tobias Wolf , Derek Driggs , Kostas Papafitsoros , Elena Resmerita , Carola-Bibiane Schönlieb

In this contribution, we are concerned with model order reduction in the context of iterative regularization methods for the solution of inverse problems arising from parameter identification in elliptic partial differential equations. Such…

Numerical Analysis · Mathematics 2024-10-14 Michael Kartmann , Tim Keil , Mario Ohlberger , Stefan Volkwein , Barbara Kaltenbacher

We study multi-parameter regularization (multiple penalties) for solving linear inverse problems to promote simultaneously distinct features of the sought-for objects. We revisit a balancing principle for choosing regularization parameters…

Numerical Analysis · Mathematics 2013-06-26 Kazufumi Ito , Bangti Jin , Tomoya Takeuchi

We consider an $\ell_1$-regularized inverse problem where both the forward and regularization operators have a Kronecker product structure. By leveraging this structure, a joint decomposition can be obtained using generalized singular value…

Numerical Analysis · Mathematics 2024-09-04 Brian Sweeney , Malena I. Español , Rosemary Renaut

We study the application of the Augmented Lagrangian Method to the solution of linear ill-posed problems. Previously, linear convergence rates with respect to the Bregman distance have been derived under the classical assumption of a…

Numerical Analysis · Mathematics 2015-06-04 Klaus Frick , Markus Grasmair

The convergence rates results in $\ell^1$-regularization when the sparsity assumption is narrowly missed, presented by Burger et al. (2013 Inverse Problems 29 025013), are based on a crucial condition which requires that all basis elements…

Numerical Analysis · Mathematics 2015-08-05 Stephan W. Anzengruber , Bernd Hofmann , Ronny Ramlau

In this work we present a novel optimization strategy for image reconstruction tasks under analysis-based image regularization, which promotes sparse and/or low-rank solutions in some learned transform domain. We parameterize such…

Computer Vision and Pattern Recognition · Computer Science 2023-08-11 Iaroslav Koshelev , Stamatios Lefkimmiatis

Two new hybrid algorithms are proposed for large-scale linear discrete ill-posed problems in general-form regularization. They are both based on Krylov subspace inner-outer iterative algorithms. At each iteration, they need to solve a…

Numerical Analysis · Mathematics 2024-09-02 Yanfei Yang

A computational method is introduced for choosing the regularization parameter for total variation (TV) regularization. The approach is based on computing reconstructions at a few different resolutions and various values of regularization…

Regularization is used in many different areas of optimization when solutions are sought which not only minimize a given function, but also possess a certain degree of regularity. Popular applications are image denoising, sparse regression…

Optimization and Control · Mathematics 2021-11-15 Bennet Gebken , Katharina Bieker , Sebastian Peitz

Algorithms for automatically selecting a scalar or locally varying regularization parameter for total variation models with an $L^{\tau}$-data fidelity term, $\tau\in \{1,2\}$, are presented. The automated selection of the regularization…

Numerical Analysis · Mathematics 2017-01-02 Andreas Langer

Connected with the rise of interest in inverse problems is the development and analysis of regularization methods, which are a necessity due to the ill-posedness of inverse problems. Tikhonov-type regularization methods are very popular in…

Numerical Analysis · Mathematics 2021-03-16 Abinash Nayak

In this paper we propose a quantum algorithm to determine the Tikhonov regularization parameter and solve the ill-conditioned linear equations, for example, arising from the finite element discretization of linear or nonlinear inverse…

Quantum Physics · Physics 2018-12-27 Changpeng Shao , Hua Xiang

We address the image restoration problem under Poisson noise corruption. The Kullback-Leibler divergence, which is typically adopted in the variational framework as data fidelity term in this case, is coupled with the second-order Total…

Numerical Analysis · Mathematics 2022-05-27 Daniela di Serafino , Monica Pragliola

In high-dimensional and/or non-parametric regression problems, regularization (or penalization) is used to control model complexity and induce desired structure. Each penalty has a weight parameter that indicates how strongly the structure…

Machine Learning · Statistics 2017-03-30 Jean Feng , Noah Simon

We propose the use of $\ell_1$ regularization in a wavelet basis for the solution of linearized seismic tomography problems $Am=d$, allowing for the possibility of sharp discontinuities superimposed on a smoothly varying background. An…

Geophysics · Physics 2009-11-13 Ignace Loris , Guust Nolet , Ingrid Daubechies , F. A. Dahlen

This paper is devoted to the understanding of regularisation process in the shape optimization approach to the so-called Dirichlet inverse obstacle problem for elliptic operators. More precisely, we study two different regularisations of…

Optimization and Control · Mathematics 2024-04-05 Fabien Caubet , Marc Dambrine , Jérémi Dardé

It is now well understood that $\ell_1$ minimization algorithm is able to recover sparse signals from incomplete measurements [2], [1], [3] and sharp recoverable sparsity thresholds have also been obtained for the $\ell_1$ minimization…

Probability · Mathematics 2009-04-07 Weiyu Xu , M. Amin Khajehnejad , Salman Avestimehr , Babak Hassibi
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