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The logarithmic representation of infinitesimal generators is generalized to the cases when the evolution operator is unbounded. The generalized result is applicable to the representation of infinitesimal generators of unbounded evolution…

Functional Analysis · Mathematics 2023-01-11 Yoritaka Iwata

In this paper, we consider the pointwise convergence for a class of generalized Schr\"{o}dinger operators with suitable perturbations, and convergence rate for a class of generalized Schr\"{o}dinger operators with polynomial growth. We show…

Classical Analysis and ODEs · Mathematics 2021-08-31 Wenjuan Li , Huiju Wang

In this paper, subnormal operators, not necessarily bounded, are discussed as generalized observables. In order to describe not only the information about the probability distribution of the output data of their measurement but also a…

Quantum Physics · Physics 2009-11-06 Masahito Hayashi , Fuminori Sakaguchi

We consider the space of abstract Uryson operators firstly introduced in [9]. We obtain the formulas for band projections on the band generated by increasing set of a positive Uryson operators and on the band generated one-dimensional…

Functional Analysis · Mathematics 2013-09-25 M. A. Ben Amor , M. Pliev

Error estimation of difference operators on irregular nodes is discussed. We can obtain the similar estimates of the errors. However, the error estimate for the difference operators for the second derivatives becomes lower because of…

Numerical Analysis · Mathematics 2017-07-04 Hiroshi Isshiki , Takafumi Kawamura , Daisuke Kitazawa

The problem of construction of projection operators on eigen-subspaces of symmetry operators is considered. This problem arises in many approximate methods for solving time-independent and time-dependent quantum problems, and its solution…

Quantum Physics · Physics 2019-10-08 Artur F. Izmaylov

For a general class of non-negative functions defined on integral ideals of number fields, upper bounds are established for their average over the values of certain principal ideals that are associated to irreducible binary forms with…

Number Theory · Mathematics 2018-03-28 T. D. Browning , E. Sofos

Jordan operator algebras are norm-closed spaces of operators on a Hilbert space which are closed under the Jordan product. The discovery of the present paper is that there exists a huge and tractable theory of possibly nonselfadjoint Jordan…

Operator Algebras · Mathematics 2017-12-20 David P. Blecher , Zhenhua Wang

Operator splitting techniques have recently gained popularity in convex optimization problems arising in various control fields. Being fixed-point iterations of nonexpansive operators, such methods suffer many well known downsides, which…

Optimization and Control · Mathematics 2020-04-01 Andreas Themelis , Panagiotis Patrinos

Manifold optimization is ubiquitous in computational and applied mathematics, statistics, engineering, machine learning, physics, chemistry and etc. One of the main challenges usually is the non-convexity of the manifold constraints. By…

Optimization and Control · Mathematics 2019-06-14 Jiang Hu , Xin Liu , Zaiwen Wen , Yaxiang Yuan

Averaging certain class of quasiperiodic monotone operators can be simplified to the periodic homogenization setting by mapping the original quasiperiodic structure onto a periodic structure in a higher dimensional space using cut-and…

Analysis of PDEs · Mathematics 2023-06-21 Niklas Wellander , Sebastien Guenneau , Elena Cherkaev

We study weighted composition operators acting between Fock spaces. The following results are obtained: (1) Criteria for the boundedness and compactness; (2) Characterizations of compact differences and essential norm; (3) Complete…

Complex Variables · Mathematics 2017-04-13 Pham Trong Tien , Le Hai Khoi

Approximate learning machines have become popular in the era of small devices, including quantised, factorised, hashed, or otherwise compressed predictors, and the quest to explain and guarantee good generalisation abilities for such…

Machine Learning · Computer Science 2022-03-16 Andrew J. Turner , Ata Kabán

Many optimization algorithms$\unicode{x2013}$including gradient descent, proximal methods, and operator splitting techniques$\unicode{x2013}$can be formulated as fixed-point iterations (FPI) of continuous operators. When these operators are…

Optimization and Control · Mathematics 2025-11-03 Kira van Treek , Javier F. Peña , Juan C. Vera , Luis F. Zuluaga

In this paper, we investigate the algebras of consequence operators and finite consequence operators on a fixed language. Significant new collections of consequence operators are defined and shown to be complete and distributive…

Logic · Mathematics 2013-05-24 Robert A. Herrmann

The play operator minimalizes the total variation on intervals $[0,T], T> 0$, of functions approximating uniformly given regulated function with given accuracy and starting from a given point. In this article we link the play operator with…

Classical Analysis and ODEs · Mathematics 2017-06-26 R. Ghomrasni , R. Łochowski

We apply modern techniques of dyadic harmonic analysis to obtain sharp estimates for the Bergman projection in weighted Bergman spaces. Our main theorem focuses on the Bergman projection on the Hartogs triangle. The estimates of the…

Complex Variables · Mathematics 2020-08-05 Zhenghui Huo , Brett D. Wick

An acute look at \underbar{basic} facts concerning \underbar{unbounded} subnormal operators is taken here. These operators have the richest structure and are the most exciting among the whole family of beneficiaries of the normal ones.…

Functional Analysis · Mathematics 2009-07-01 F. H. Szafraniec

Proper splittings of operators are commonly used to study the convergence of iterative processes. In order to approximate solutions of operator equations, in this article we deal with proper splittings of closed range bounded linear…

Functional Analysis · Mathematics 2024-03-18 Guillermina Fongi , María Celeste Gonzalez

We give necessary and sufficient conditions for a bounded operator defined between complex Hilbert spaces to be absolutely norm attaining. We discuss structure of such operators in the case of self-adjoint and normal operators separately.…

Spectral Theory · Mathematics 2018-01-09 G. Ramesh , D. Venku Naidu