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So-called functional error estimators provide a valuable tool for reliably estimating the discretization error for a sum of two convex functions. We apply this concept to Tikhonov regularization for the solution of inverse problems for…

Numerical Analysis · Mathematics 2017-02-13 Christian Clason , Barbara Kaltenbacher , Daniel Wachsmuth

We prove partial regularity of stationary solutions and minimizers $u$ from a set $\Omega\subset \mathbb R^n$ to a Riemannian manifold $N$, for the functional $\int_\Omega F(x,u,|\nabla u|^2) dx$. The integrand $F$ is convex and satisfies…

Differential Geometry · Mathematics 2017-08-21 Zahra Sinaei

Fractional Tikhonov regularization methods have been recently proposed to reduce the oversmoothing property of the Tikhonov regularization in standard form, in order to preserve the details of the approximated solution. Their regularization…

Numerical Analysis · Mathematics 2020-09-07 Davide Bianchi , Alessandro Buccini , Marco Donatelli , Stefano Serra-Capizzano

The goal of this paper is to further develop an approach to inverse problems with imperfect forward operators that is based on partially ordered spaces. Studying the dual problem yields useful insights into the convergence of the…

Numerical Analysis · Mathematics 2019-01-30 Martin Burger , Yury Korolev , Julian Rasch

Regularizing a linear ill-posed operator equation can be achieved by manipulating the spectrum of the operator's pseudo-inverse. Tikhonov regularization and spectral cutoff are well-known techniques within this category. This paper…

Numerical Analysis · Mathematics 2026-02-11 Martin Sæbye Carøe , Mirza Karamehmedović , Pierre Maréchal

This paper is concerned with exponentially ill-posed operator equations with additive impulsive noise on the right hand side, i.e. the noise is large on a small part of the domain and small or zero outside. It is well known that Tikhonov…

Numerical Analysis · Mathematics 2016-03-18 Claudia König , Frank Werner , Thorsten Hohage

In the context of image processing, given a $k$-th order, homogeneous and linear differential operator with constant coefficients, we study a class of variational problems whose regularizing terms depend on the operator. Precisely, the…

Numerical Analysis · Mathematics 2022-11-15 Valerio Pagliari , Kostas Papafitsoros , Bogdan Raiţă , Andreas Vikelis

This paper deals with Tikhonov regularization for linear and nonlinear ill-posed operator equations with wavelet Besov norm penalties. We show order optimal rates of convergence for finitely smoothing operators and for the backwards heat…

Numerical Analysis · Mathematics 2019-04-03 Frederic Weidling , Benjamin Sprung , Thorsten Hohage

In this article we propose a novel nonstationary iterated Tikhonov (NIT) type method for obtaining stable approximate solutions to ill-posed operator equations modeled by linear operators acting between Hilbert spaces. Geometrical…

Numerical Analysis · Mathematics 2020-11-12 R. Boiger , A. Leitao , B. F. Svaiter

Tikhonov regularization is a common technique used when solving poorly behaved optimization problems. Often, and with good reason, this technique is applied by practitioners in an ad hoc fashion. In this note, we systematically illustrate…

Optimization and Control · Mathematics 2022-12-16 J. Adriazola

In a series of publications of the second author, including some with coauthors, globally strictly convex Tikhonov-like functionals were constructed for some nonlinear ill-posed problems. The main element of such a functional is the…

Analysis of PDEs · Mathematics 2016-08-10 Anatoly B. Bakushinskii , Michael V. Klibanov , Nikolaj A. Koshev

In this paper, we study a fractional-order variant of the asymptotical regularization method, called {\it Fractional Asymptotical Regularization (FAR)}, for solving linear ill-posed operator equations in a Hilbert space setting. We assign…

Numerical Analysis · Mathematics 2019-07-16 Ye Zhang , Bernd Hofmann

In this work, we propose Regularization-by-Equivariance (REV), a novel structure-adaptive regularization scheme for solving imaging inverse problems under incomplete measurements. This regularization scheme utilizes the equivariant…

Optimization and Control · Mathematics 2022-02-15 Junqi Tang

In this paper, we investigate an ill-posed Cauchy problem involving a stochastic parabolic equation. We first establish a Carleman estimate for this equation. Leveraging this estimate, we derive the conditional stability and convergence…

Numerical Analysis · Mathematics 2024-05-13 Fangfang Dou , Peimin Lü , Yu Wang

We present a family of non-local variational regularization methods for solving tomographic problems, where the solutions are functions with range in a closed subset of the Euclidean space, for example if the solution only attains values in…

Optimization and Control · Mathematics 2019-11-18 Melanie Melching , Otmar Scherzer

We study variational regularisation methods for inverse problems with imperfect forward operators whose errors can be modelled by order intervals in a partial order of a Banach lattice. We carry out analysis with respect to existence and…

Numerical Analysis · Mathematics 2020-12-25 Leon Bungert , Martin Burger , Yury Korolev , Carola-Bibiane Schoenlieb

The Tikhonov-Phillips method is widely used for regularizing ill-posed inverse problems mainly due to the simplicity of its formulation as an optimization problem. The use of different penalizers in the functionals associated to the…

Functional Analysis · Mathematics 2011-08-23 Gisela L. Mazzieri , Ruben D. Spies , Karina G. Temperini

In this paper we propose a new class of iterative regularization methods for solving ill-posed linear operator equations. The prototype of these iterative regularization methods is in the form of second order evolution equation with a…

Numerical Analysis · Mathematics 2020-06-24 Rongfang Gong , B. Hofmann , Ye Zhang

Consider an operator equation $F(u)=0$ in a real Hilbert space. Let us call this equation ill-posed if the operator $F'(u)$ is not boundedly invertible, and well-posed otherwise. If $F$ is monotone $C^2_{loc}(H)$ operator, then we construct…

Dynamical Systems · Mathematics 2016-09-07 A. G. Ramm

We consider regularization methods based on the coupling of Tikhonov regularization and projection strategies. From the resulting constraint regularization method we obtain level set methods in a straight forward way. Moreover, we show that…

Optimization and Control · Mathematics 2020-11-17 A. Leitao , O. Scherzer
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