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In this paper, we study spaceability of subsets of generalized Orlicz and Lebesgue spaces associated to Banach function space. Also, we give some sufficient conditions for spaceability of subsets of a general Banach space which improves an…

Functional Analysis · Mathematics 2022-08-09 Alireza Bagheri Salec , Stefan Ivkovic , Seyyed Mohammad Tabatabaie

We study the typical behavior of bounded linear operators on infinite dimensional complex separable Hilbert spaces in the norm, strong-star, strong, weak polynomial and weak topologies. In particular, we investigate typical spectral…

Functional Analysis · Mathematics 2014-05-01 Tanja Eisner , Tamas Matrai

The numerical range of a bounded linear operator on a complex Banach space need not be convex unlike that on a Hilbert space. The aim of this paper is to study operators $T$ on $ \ell^2_p $ for which the numerical range is convex. We also…

Functional Analysis · Mathematics 2024-08-13 Kalidas Mandal , Aniket Bhanja , Santanu Bag , Kallol Paul

We consider various notions of equivalence in the space of bounded operators on a Hilbert space, in particular modulo finite rank, modulo Schatten $p$-class, and modulo compact. Using Hjorth's theory of turbulence, the latter two are shown…

Logic · Mathematics 2024-07-22 Iian B. Smythe

The purpose of this note is to show that, if $\mcB$ is a uniformly convex Banach, then the dual space $\mcB'$ has a "Hilbert space representation" (defined in the paper), that makes $\mcB$ much closer to a Hilbert space then previously…

Functional Analysis · Mathematics 2015-07-31 Tepper L. Gill , Marzett Golden

It has been very recently discovered that there are compact linear operators between Banach spaces which cannot be approximated by norm attaining operators. The aim of this expository paper is to give an overview of those examples and also…

Functional Analysis · Mathematics 2017-04-25 Miguel Martin

We consider similarity transformations of a perturbed linear operator $A-B$ in a complex Banach space $\mathcal{X}$, where the unperturbed operator $A$ is a generator of a Banach $L_1(\mathbb{R})$-module and the perturbation operator $B$ is…

Functional Analysis · Mathematics 2024-04-02 Anatoly G. Baskakov , Ilya A. Krishtal , Natalia B. Uskova

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

This paper extends topics in linear algebra and operator theory for linear transformations on complex vector spaces to those on bicomplex Hilbert and Banach spaces. For example, Definition 3 for the first time defines a bicomplex vector…

Functional Analysis · Mathematics 2023-05-23 William Johnston , Rebecca G. Wahl

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 establish a spectral characterization theorem for the operators on complex Hilbert spaces of arbitrary dimensions that attain their norm on every closed subspace. The class of these operators is not closed under addition. Nevertheless,…

Functional Analysis · Mathematics 2016-07-13 Satish K. Pandey , Vern I. Paulsen

Following several papers in the prior literature, we study the relationship between order bounded operators, topologically bounded operators and topologically continuous operators. Our main contribution is two folded: (i) we provide a set…

Functional Analysis · Mathematics 2018-04-12 Liang Hong

This paper deals with study of Birkhoff-James orthogonality of a linear operator to a subspace of operators defined between arbitrary Banach spaces. In case the domain space is reflexive and the subspace is finite dimensional we obtain a…

Functional Analysis · Mathematics 2019-12-10 Arpita Mal , Kallol Paul

We study uniform $\epsilon-$BPB approximations of bounded linear operators between Banach spaces from a geometric perspective. We show that for sufficiently small positive values of $\epsilon,$ many geometric properties like smoothness,…

Functional Analysis · Mathematics 2024-08-14 Debmalya Sain , Arpita Mal , Kalidas Mandal , Kallol Paul

We give a few observations on different types of bounded operators on a topological vector space X and their relations with compact operators on X. In particular, we investigate when these bounded operators coincide with compact operators.…

Functional Analysis · Mathematics 2015-08-25 Ljubisa D. R. Kocinac , Omid Zabeti

We introduce a class of linear bounded invertible operators on Banach spaces, called shift operators, which comprises weighted backward shifts and models finite products of weighted backward shifts and dissipative composition operators. We…

Dynamical Systems · Mathematics 2024-07-31 Maria Carvalho , Udayan B. Darji , Paulo Varandas

We show that there is an operator space notion of Lipschitz embeddability between operator spaces which is strictly weaker than its linear counterpart but which is still strong enough to impose linear restrictions on operator space…

Operator Algebras · Mathematics 2022-11-28 Bruno de Mendonça Braga , Javier Alejandro Chávez-Domínguez , Thomas Sinclair

On finite dimensional spaces, it is apparent that an operator is the product of two positive operators if and only if it is similar to a positive operator. Here, the class ${\mathcal L}^{+2}$ of bounded operators on separable infinite…

Functional Analysis · Mathematics 2021-01-27 Maximiliano Contino , Michael A. Dritschel , Alejandra Maestripieri , Stefania Marcantognini

A linear operator $U$ acting boundedly on an infinite-dimensional separable complex Hilbert space $H$ is universal if every linear bounded operator acting on $H$ is similar to a scalar multiple of a restriction of $U$ to one of its…

Functional Analysis · Mathematics 2024-06-05 Luciano Abadías , F. Javier González-Doña , Jesús Oliva-Maza

We study Birkhoff-James orthogonality and isosceles orthogonality of bounded linear operators between Hilbert spaces and Banach spaces. We explore Birkhoff-James orthogonality of bounded linear operators in light of a new notion introduced…

Functional Analysis · Mathematics 2020-04-28 Tamara Bottazzi , Cristian Conde , Debmalya Sain