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In this work, we develop and study an empirical projection operator scheme for solving nonparametric regression problems. This scheme is based on an approximate projection of the regression function over a suitable reproducing kernel…

Statistics Theory · Mathematics 2020-02-04 Bilel Bousselmi , Jean-François Dupuy , Abderrazek Karoui

The standard theoretical descriptions of the dynamics of open quantum systems rely on the assumption that the correlations with the environment can be neglected at some reference (initial) time. While being reasonable in specific instances,…

Quantum Physics · Physics 2021-11-22 Andrea Trevisan , Andrea Smirne , Nina Megier , Bassano Vacchini

A notion of curvature is introduced in multivariable operator theory and an analogue of the Gauss-Bonnet-Chern theorem is established for graded (contractive) Hilbert modules over the complex polynomial algebra in d variables, d=1,2,3,....…

Operator Algebras · Mathematics 2007-05-23 William Arveson

Strongly correlated electron systems require the development of new theoretical schemes in order to describe their unusual and unexpected properties. The usual perturbation schemes are inadequate and new concepts must be introduced. In our…

Strongly Correlated Electrons · Physics 2016-08-31 F. Mancini , A. Avella

We present a straightforward, noniterative projection scheme that can represent the electronic ground state of a periodic system on a finite atomic-orbital-like basis, up to a predictable number of electronic states and with controllable…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Luis A. Agapito , Andrea Ferretti , Arrigo Calzolari , Stefano Curtarolo , Marco Buongiorno Nardelli

In this note we describe how some objects from generalized geometry appear in the qualitative analysis and numerical simulation of mechanical systems. In particular we discuss double vector bundles and Dirac structures. It turns out that…

Numerical Analysis · Mathematics 2018-07-19 Vladimir Salnikov , Aziz Hamdouni

Coherent states possess a regularized path integral and gives a natural relation between classical variables and quantum operators. Recent work by Klauder and Whiting has included extended variables, that can be thought of as gauge fields,…

Quantum Physics · Physics 2008-02-03 M. C. Ashworth

The projectability of Poincar\'e-Cartan forms in a third-order jet bundle $J^3\pi$ onto a lower-order jet bundle is a consequence of the degenerate character of the corresponding Lagrangian. This fact is analyzed using the constraint…

Mathematical Physics · Physics 2017-12-29 Jordi Gaset , Narciso Román-Roy

This paper is devoted to self-adjoint cyclically compact operators on Hilbert--Kaplansky module over a ring of bounded measurable functions. The spectral theorem for such a class of operators are given. We apply this result to partial…

Operator Algebras · Mathematics 2015-02-10 Farrukh Mukhamedov , Karimbergen Kudaybergenov

In this chapter, the Hilbert space framework in the mathematical theory of composite materials is introduced for studying the properties of effective operators. The goal is to introduce some of the key concepts and fundamental theorems in…

Mathematical Physics · Physics 2025-12-11 Aaron Welters

Many machine learning approaches for decision making, such as reinforcement learning, rely on simulators or predictive models to forecast the time-evolution of quantities of interest, e.g., the state of an agent or the reward of a policy.…

Machine Learning · Computer Science 2024-01-17 Petar Bevanda , Max Beier , Armin Lederer , Stefan Sosnowski , Eyke Hüllermeier , Sandra Hirche

Gaussian processes (GPs) are ubiquitous tools for modeling and predicting continuous processes in physical and engineering sciences. This is partly due to the fact that one may employ a Gaussian process as an interpolator while facilitating…

Statistics Theory · Mathematics 2025-12-16 D. Andrew Brown , Peter Kiessler , John Nicholson

We consider linear ill-conditioned operator equations in a Hilbert space setting. Motivated by the aggregation method, we consider approximate solutions constructed from linear combinations of Tikhonov regularization, which amounts to…

Numerical Analysis · Mathematics 2023-06-07 Stefan Kindermann , Werner Zellinger

Quantum optimal control is an important technology that enables fast state preparation and gate design. In the absence of an analytic solution, most quantum optimal control methods rely on an iterative scheme to update the solution…

Quantum Physics · Physics 2022-10-27 Jieqiu Shao , Joshua Combes , John Hauser , Marco M. Nicotra

An approach is proposed which, given a family of linearly independent functions, constructs the appropriate biorthogonal set so as to represent the orthogonal projector operator onto the corresponding subspace. The procedure evolves…

Mathematical Physics · Physics 2007-05-23 laura Rebollo-Neira

A weighted composition operator on a reproducing kernel Hilbert space is given by a composition, followed by a multiplication. We study unitary and co-isometric weighted composition operators on unitarily invariant spaces on the Euclidean…

Functional Analysis · Mathematics 2025-12-23 Michael Hartz , Maximilian Tornes

This paper presents a novel Koopman composition operator representation framework for control systems in reproducing kernel Hilbert spaces (RKHSs) that is free of explicit dictionary or input parametrizations. By establishing fundamental…

Systems and Control · Electrical Eng. & Systems 2025-09-03 Petar Bevanda , Bas Driessen , Lucian Cristian Iacob , Stefan Sosnowski , Roland Tóth , Sandra Hirche

This paper presents the first results to combine two theoretically sound methods (spectral projection and multigrid methods) together to attack ill-conditioned linear systems. Our preliminary results show that the proposed algorithm applied…

Numerical Analysis · Mathematics 2016-02-18 Craig C. Douglas , Long Lee , Man-Chung Yeung

The discretization of least-squares problems for linear ill-posed operator equations in Hilbert spaces is considered. The main subject of this article concerns conditions for convergence of the associated discretized minimum-norm…

Numerical Analysis · Mathematics 2016-02-10 Stefan Kindermann

Convergence of a projected stochastic gradient algorithm is demonstrated for convex objective functionals with convex constraint sets in Hilbert spaces. In the convex case, the sequence of iterates ${u_n}$ converges weakly to a point in the…

Optimization and Control · Mathematics 2019-10-01 Caroline Geiersbach , Georg Pflug