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Local solutions for variational and quasi-variational inequalities are usually the best type of solutions that could practically be obtained when in case of lack of convexity or else when available numerical techniques are too limited for…

Optimization and Control · Mathematics 2024-05-16 Didier Aussel , Parin Chaipunya

We consider whether minimizers for total variation regularization of linear inverse problems belong to $L^\infty$ even if the measured data does not. We present a simple proof of boundedness of the minimizer for fixed regularization…

Optimization and Control · Mathematics 2023-06-28 Kristian Bredies , José A. Iglesias , Gwenael Mercier

We study the problem of super-resolution, where we recover the locations and weights of non-negative point sources from a few samples of their convolution with a Gaussian kernel. It has been shown that exact recovery is possible by…

Optimization and Control · Mathematics 2023-07-06 Stéphane Chrétien , Andrew Thompson , Bogdan Toader

The focus of this article is the approximation of functions which are analytic on a compact interval except at the endpoints. Typical numerical methods for approximating such functions depend upon the use of particular conformal maps from…

Numerical Analysis · Mathematics 2014-05-05 Ben Adcock , Mark Richardson

Consider a nonlinear ill-posed operator equation $F(u)=y$ where $F$ is defined on a Banach space $X$. In general, for solving this equation numerically, a finite dimensional approximation of $X$ and an approximation of $F$ are required.…

Numerical Analysis · Mathematics 2015-05-18 C. Poeschl , E. Resmerita , O. Scherzer

We present a powerful and easy-to-implement algorithm for solving constrained optimization problems that involve $L_1$/total-variation regularization terms, and both equality and inequality constraints. We discuss the relationship of our…

Optimization and Control · Mathematics 2015-05-22 Musa Maharramov , Stewart A. Levin

The problem of prediction in functional linear regression is conventionally addressed by reducing dimension via the standard principal component basis. In this paper we show that an alternative basis chosen through weighted least-squares,…

Methodology · Statistics 2009-02-20 Aurore Delaigle , Peter Hall , Tatiyana V. Apanasovich

Regularization plays a pivotal role when facing the challenge of solving ill-posed inverse problems, where the number of observations is smaller than the ambient dimension of the object to be estimated. A line of recent work has studied…

Optimization and Control · Mathematics 2014-07-03 Samuel Vaiter , Mohammad Golbabaee , Jalal M. Fadili , Gabriel Peyré

This paper is concerned with a novel regularisation technique for solving linear ill-posed operator equations in Hilbert spaces from data that is corrupted by white noise. We combine convex penalty functionals with extreme-value statistics…

Statistics Theory · Mathematics 2012-04-03 Klaus Frick , Philipp Marnitz , Axel Munk

This work combines three paradigms of image processing: i) the total variation approach to denoising, ii) the superior structure of hexagonal lattices, and iii) fast and exact graph cut optimization techniques. Although isotropic in theory,…

Optimization and Control · Mathematics 2012-04-18 Clemens Kirisits

This investigation is motivated by PDE-constrained optimization problems arising in connection with electrocardiograms (ECGs) and electroencephalography (EEG). Standard sparsity regularization does not necessarily produce adequate results…

Numerical Analysis · Mathematics 2023-05-25 Ole Løseth Elvetun , Bjørn Fredrik Nielsen

In this work we study weighted total least squares problems on infinite dimensional spaces. We show that in most cases this problem does not admit a solution (except in the trivial case) and then, we consider a regularization on the…

Functional Analysis · Mathematics 2021-05-26 Maximiliano Contino , Guillermina Fongi , Alejandra Maestripieri , Santiago Muro

We propose an efficient estimation technique for the automatic selection of locally-adaptive Total Variation regularisation parameters based on an hybrid strategy which combines a local maximum-likelihood approach estimating space-variant…

Optimization and Control · Mathematics 2020-05-20 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

This paper considers the use of total variation regularization in the recovery of approximately gradient sparse signals from their noisy discrete Fourier samples in the context of compressed sensing. It has been observed over the last…

Numerical Analysis · Mathematics 2014-07-22 Clarice Poon

For linear ill-posed problems with nontrivial null spaces, Tikhonov regularization and truncated singular value decomposition (TSVD) typically yield solutions that are close to the minimum norm solution. Such a bias is not always desirable,…

Numerical Analysis · Mathematics 2024-12-10 Ole Løseth Elvetun , Kim Knudsen , Bjørn Fredrik Nielsen

This thesis is devoted to exploring various fundamental issues within asymptotic safety. Firstly, we study the reconstruction problem and present two ways in which to solve it within the context of scalar field theory, by utilising a…

High Energy Physics - Theory · Physics 2018-12-19 Zoë H. Slade

In this paper, we first propose a concept of weighted pseudo-almost periodic functions on time scales and study some basic properties of weighted pseudo-almost periodic functions on time scales. Then, we establish some results about the…

Classical Analysis and ODEs · Mathematics 2016-07-28 Yongkun Li , Lili Zhao

We study the problem of super-resolution, where we recover the locations and weights of non-negative point sources from a few samples of their convolution with a Gaussian kernel. It has been recently shown that exact recovery is possible by…

Optimization and Control · Mathematics 2019-05-09 Stephane Chretien , Andrew Thompson , Bogdan Toader

In this paper, we consider an inverse space-dependent source problem for a time-fractional diffusion equation. To deal with the ill-posedness of the problem, we transform the problem into an optimal control problem with total variational…

Optimization and Control · Mathematics 2025-01-15 Bin Fan

Regularization is a critical technique for ensuring well-posedness in solving inverse problems with incomplete measurement data. Traditionally, the regularization term is designed based on prior knowledge of the unknown signal's…

Numerical Analysis · Mathematics 2024-12-16 Bosu Choi , Jihun Han , Yoonsang Lee