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We describe a set of conformally covariant boundary operators associated to the Paneitz operator, in the sense that they give rise to a conformally covariant energy functional for the Paneitz operator on a compact Riemannian manifold with…

Differential Geometry · Mathematics 2015-09-29 Jeffrey S. Case

There has been a long-standing conjecture in Banach algebra that every amenable operator is similar to a normal operator. In this paper, we study the structure of amenable operators on Hilbert spaces. At first, we show that the conjecture…

Functional Analysis · Mathematics 2010-09-01 Luo Yi Shi , Yu Jing Wu , You Qing Ji

We consider Schr\"odinger operators on possibly noncompact Riemannian manifolds, acting on sections in vector bundles, with locally square integrable potentials whose negative part is in the underlying Kato class. Using path integral…

Mathematical Physics · Physics 2012-12-10 Batu Güneysu , Olaf Post

It is well known that, given an equivariant and continuous (in a suitable sense) family of selfadjoint operators in a Hilbert space over a minimal dynamical system, the spectrum of all operators from that family coincides. As shown recently…

Spectral Theory · Mathematics 2016-12-22 Siegfried Beckus , Daniel Lenz , Marko Lindner , Christian Seifert

A closed subspace of a Banach space $\cX$ is almost-invariant for a collection $\cS$ of bounded linear operators on $\cX$ if for each $T \in \cS$ there exists a finite-dimensional subspace $\cF_T$ of $\cX$ such that $T \cY \subseteq \cY +…

Functional Analysis · Mathematics 2012-04-23 Laurent W. Marcoux , Alexey I. Popov , Heydar Radjavi

First we give conditions on a Banach lattice $E$ so that an operator $T$ from $E$ to any Banach space is disjoint $p$-convergent if and only if $T$ is almost Dunford-Pettis. Then we study when adjoints of positive operators between Banach…

Functional Analysis · Mathematics 2023-09-22 Geraldo Botelho , Luis Alberto Garcia , Vinícius C. C. Miranda

In this paper, we investigate the spectrum of the self adjoint differential operator with operator coefficitent in a separable Hilbert space. We also derive asymptotic formulas for the sum of eigenvalues of this operator.

Spectral Theory · Mathematics 2019-09-10 Yonca Sezer , Özlem Bakşi

In the paper is considered two problems on extension of operators whose range space for the first problem (or domain space for the second one) belongs to the fixed class of finite equivalence, which is generated by a given Banach space $X$.…

Functional Analysis · Mathematics 2007-05-23 Eugene Tokarev

The first representation theorem establishes a correspondence between positive, self-adjoint operators and closed, positive forms on Hilbert spaces. The aim of this paper is to show that some of the results remain true if the underlying…

Functional Analysis · Mathematics 2007-05-23 Balint Farkas , Mate Matolcsi

The main aim of this book is to present recent results concerning inequalities for continuous functions of selfadjoint operators on complex Hilbert spaces. It is intended for use by both researchers in various fields of Linear Operator…

Functional Analysis · Mathematics 2012-03-09 Silvestru Sever Dragomir

We study best approximations to compact operators between Banach spaces and Hilbert spaces, from the point of view of Birkhoff-James orthogonality and semi-inner-products. As an application of the present study, some distance formulae are…

Functional Analysis · Mathematics 2021-04-30 Debmalya Sain

This is a series of 5 lectures around the common subject of the construction of self-adjoint extensions of symmetric operators and its applications to Quantum Physics. We will try to offer a brief account of some recent ideas in the theory…

Mathematical Physics · Physics 2015-02-19 A. Ibort , J. M. Perez-Pardo

In this work, we prove that linear bounded operators $T$ on a Banach space $X$ allowing spectral cuts along rectifiable Jordan curves meeting their spectrum are related to classes of operators admitting an unconventional functional…

Functional Analysis · Mathematics 2026-03-24 Eva A. Gallardo-Gutiérrez , F. Javier González-Doña

For a certain class of algebras $\cal A$ we give a method for constructing Banach spaces $X$ such that every operator on $X$ is close to an operator in $\cal A$. This is used to produce spaces with a small amount of structure. We present…

Functional Analysis · Mathematics 2008-09-01 W. T. Gowers , B. Maurey

We study extension theorems for Lipschitz-type operators acting on metric spaces and with values on spaces of integrable functions. Pointwise domination is not a natural feature of such spaces, and so almost everywhere inequalities and…

Functional Analysis · Mathematics 2019-10-02 W. V. Cavalcante , P. Rueda , E. A. Sánchez-Pérez

This paper is a sequel to [6]. In that paper we transferred the discussions in [1] and [13] concerning almost invariant half-spaces for operators on complex Banach spaces to the context of operators on Hilbert space, and we gave easier…

Functional Analysis · Mathematics 2017-10-30 Il Bong Jung , Eungil Ko , Carl Pearcy

We extend the concept of Lifshits--Krein spectral shift function associated with a pair of self-adjoint operators to the case of pairs of admissible operators that are similar to self-adjoint operators. Our main result is the following. Let…

Spectral Theory · Mathematics 2019-09-11 Sergio Albeverio , Konstantin A. Makarov , Alexander K. Motovilov

This paper introduces a new definition of $\alpha$-monotone operators in real 2-uniformly convex and smooth Banach spaces. Based on this new definition, we establish several novel structural and analytical properties of such operators,…

Functional Analysis · Mathematics 2025-10-15 Changchi Huang , Jigen Peng , Yuchao Tang

The non-Archimedean spectral theory and spectral integration is developed. The analog of the Stone theorem is proved. Applications are considered for algebras of operators.

Spectral Theory · Mathematics 2018-12-18 S. Ludkovsky , B. Diarra

Resolvents of quasi-linear operators and operator algebras in Banach spaces over the quaternion field are investigated. Spectral theory of unbounded nonlinear operators in quaternion Banach spaces is studied. Strongly continuous semigroups…

Operator Algebras · Mathematics 2018-12-18 S. V. Ludkovsky