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In this paper we show that a result of Gross and Kuelbs, used to study Gaussian measures on Banach spaces, makes it possible to construct an adjoint for operators on separable Banach spaces. This result is used to extend well known theorems…

Mathematical Physics · Physics 2007-05-23 T. L. Gill , S. Basu , W. W. Zachary , V. Steadman

It is a longstanding problem whether every contractible Banach algebra is necessarily finite-dimensional. In this note, we confirm this for Banach algebras acting on Banach spaces with the uniform approximation property. This generalizes a…

Functional Analysis · Mathematics 2011-10-31 Narutaka Ozawa

Given a Banach space $E$, we ask which closed subspaces may be realised as the kernel of a bounded operator $E \rightarrow E$. We prove some positive results which imply in particular that when $E$ is separable every closed subspace is a…

Functional Analysis · Mathematics 2018-11-30 Niels Jakob Laustsen , Jared T. White

We show that if $x$ is a strongly extreme point of a bounded closed convex subset of a Banach space and the identity has a geometrically and topologically good enough local approximation at $x$, then $x$ is already a denting point. It turns…

Functional Analysis · Mathematics 2019-08-15 Trond A. Abrahamsen , Petr Hájek , Olav Nygaard , Stanimir Troyanski

We prove an extrapolation of compactness theorem for operators on Banach function spaces satisfying certain convexity and concavity conditions. In particular, we show that the boundedness of an operator $T$ in the weighted Lebesgue scale…

Classical Analysis and ODEs · Mathematics 2024-05-31 Emiel Lorist , Zoe Nieraeth

The goal of this paper is to study band-dominated operators on Banach spaces with Schauder basis with respect to uniformly locally finite metric spaces as well as the Banach algebras generated by them: the so called uniform Roe algebras. We…

Functional Analysis · Mathematics 2020-03-27 Bruno de Mendonça Braga

We introduce a class of (tuples of commuting) unbounded operators on a Banach space, admitting smooth functional calculi, that contains all operators of Helffer-Sj\"ostrand type and is closed under the action of smooth proper mappings.…

Spectral Theory · Mathematics 2016-08-16 Mats Andersson , Håkan Samuelsson , Sebastian Sandberg

We give criteria for the membership of Hankel operators on the Hardy space on the disc in the Dixmier class, and establish estimates for their Dixmier trace. In contrast to the situation in the Bergman space setting, it turns out that there…

Complex Variables · Mathematics 2016-01-26 Miroslav Engliš , Genkai Zhang

In this article, the class of all Dunford-Pettis $ p $-convergent operators and $ p $-Dunford-Pettis relatively compact property on Banach spaces are investigated. Moreover, we give some conditions on Banach spaces $ X $ and $ Y $ such that…

Functional Analysis · Mathematics 2019-05-06 M. Alikhani

We show that if an infinite-dimensional Banach space X has a symmetric basis then there exists a bounded, linear operator R : X --> X such that the set A = {x in X : ||R^n(x)|| --> infinity} is non-empty and nowhere dense in X. Moreover, if…

Functional Analysis · Mathematics 2022-06-14 Petr Hajek , Richard J. Smith

We construct a Banach space satisfying that the nearest point map (also called proximity mapping or metric projection) onto any compact and convex subset is continuous but not uniformly continuous. The space we construct is locally…

Functional Analysis · Mathematics 2024-02-08 Rubén Medina , Andrés Quilis

The relationship between the operator approximation property and the strong operator approximation property has deep significance in the theory of operator algebras. The original definitions of Effros and Ruan, unlike the classical…

Functional Analysis · Mathematics 2007-05-23 Corran Webster

Let $\mathcal H$ be a complex infinite-dimensional separable Hilbert space, and let $\mathcal K(\mathcal H)$ be the $C^*$-algebra of compact linear operators in $\mathcal H$. Let $(E,\|\cdot\|_E)$ be a symmetric sequence space. If…

Functional Analysis · Mathematics 2019-07-17 B. Aminov , Vladimir Chilin

We present partial results to the following question: Does every infinite dimensional Banach space have an infinite dimensional subspace on which one can define an operator which is not a compact perturbation of a scalar multiplication?

Functional Analysis · Mathematics 2007-05-23 Th. Schlumprecht

This paper deals with the problem of when, given a collection $\mathcal C$ of weakly compact operators between separable Banach spaces, there exists a separable reflexive Banach space $Z$ with a Schauder basis so that every element in…

Functional Analysis · Mathematics 2019-09-18 Leandro Antunes , Kevin Beanland , Bruno de Mendonça Braga

The concept of adjusted sublevel set for a quasiconvex function was introduced in \cite{AuHa05} and the local existence of a norm-to-weak$^*$ upper semicontinuous base-valued submap of the normal operator associated to the adjusted sublevel…

Optimization and Control · Mathematics 2023-01-31 Marco Castellani , Massimiliano Giuli

We exhibit a general class of unbounded operators in Banach spaces which can be shown to have the single-valued extension property, and for which the local spectrum at suitable points can be determined. We show that a local spectral radius…

Spectral Theory · Mathematics 2023-05-31 Nils Byrial Andersen , Marcel de Jeu

We obtain exhaustive results and treat in a unified way the question of boundedness, compactness, and weak compactness of composition operators from the Bloch space into any space from a large family of conformally invariant spaces that…

Functional Analysis · Mathematics 2016-11-07 Manuel D. Contreras , Santiago Diaz-Madrigal , Dragan Vukotic

We prove that every lattice homomorphism acting on a Banach space $\mathcal{X}$ with the lattice structure given by an unconditional basis has a non-trivial closed invariant subspace. In fact, it has a non-trivial closed invariant ideal,…

Functional Analysis · Mathematics 2020-05-05 Eva A. Gallardo-Gutiérrez , Javier González-Doña , Pedro Tradacete

We study multiplication operators on the weighted Banach spaces of an infinite tree. We characterize the bounded and the compact operators, as well as determine the operator norm. In addition, we determine the spectrum of the bounded…

Functional Analysis · Mathematics 2022-07-27 Robert F. Allen , Isaac Sundberg