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In this paper we study the reflexivity of a unital strongly closed algebra of operators with complemented invariant subspace lattice on a Banach space. We prove that if such an algebra contains a complete Boolean algebra of projections of…

Functional Analysis · Mathematics 2013-06-11 Florence Merlevède , Costel Peligrad , Magda Peligrad

The concept of complementability is extended from bounded operators to densely defined operators on Hilbert spaces. By introducing appropriate projections and decomposition techniques, a framework is developed for analyzing…

Functional Analysis · Mathematics 2025-11-27 Sachin Manjunath Naik , P. Sam Johnson

In this paper, we consider the structure of maximally monotone operators in Banach space whose domains have nonempty interior and we present new and explicit structure formulas for such operators. Along the way, we provide new proofs of the…

Functional Analysis · Mathematics 2012-03-07 Jonathan M. Borwein , Liangjin Yao

We construct a family $(\mathcal{X}_\al)_{\al\le \omega_1}$ of reflexive Banach spaces with long transfinite bases but with no unconditional basic sequences. In our spaces $\mathcal{X}_\al$ every bounded operator $T$ is split into its…

Functional Analysis · Mathematics 2007-05-23 S. A. Argyros , J. Lopez-Abad , S. Todorcevic

We give a new proof of a characterization of the closeness of the range of a continuous linear operator and of the closeness of the sum of two closed vector subspaces of a Banach space. Then we state sufficient conditions for the closeness…

Functional Analysis · Mathematics 2015-10-06 Joël Blot , Philippe Cieutat

In this paper we present some spectral property for quotient bounded operators and locally bounded operators on locally convex spaces. We introduce the spectral radius of a quotient bounded operator and we show that the Gelfand formula for…

Functional Analysis · Mathematics 2007-05-23 Mirel Sorin Stoian

In this article we discuss the solvability of some class of fully nonlinear equations, and equations with p-Laplacian in more general conditions by using a new approach given in [1] for studying the nonlinear continuous operator. Moreover…

Analysis of PDEs · Mathematics 2012-08-14 Kamal N. Soltanov

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 give sufficient conditions on an asymptotic $\ell_p$ (for $1 < p < \infty$) Banach space which ensure the space admits an operator which is not a compact perturbation of a multiple of the identity. These conditions imply the existence of…

Functional Analysis · Mathematics 2009-08-11 Kevin Beanland

We characterize the spectrum of positive linear operators $T:X \to Y$, where $X$ and $Y$ are complex Banach function spaces with unit $1$, having finite rank and a partition of unity property. Then all the points in the spectrum are…

Classical Analysis and ODEs · Mathematics 2014-03-19 Johannes Nagler

We show that operators on a separable infinite dimensional Banach space $X$ of the form $I +S$, where $S$ is an operator with dense generalised kernel, must lie in the norm closure of the hypercyclic operators on $X$, in fact in the closure…

Functional Analysis · Mathematics 2014-10-28 James Boland

Let $\mathscr{X}$ be a complex Banach space and $\mathcal{L}(\mathscr{X})$ be the algebra of all bounded linear operators on $\mathscr{X}$. For a given elementary operator $\Phi$ of length $2$ on $\mathcal{L}(\mathscr{X})$, we determine…

Functional Analysis · Mathematics 2013-12-05 Nadia Boudi , Janko Bračič

We address a question by Henry Towsner about the possibility of representing linear operators between ultraproducts of Banach spaces by means of ultraproducts of nonlinear maps. We provide a bridge between these "accessible" operators and…

Functional Analysis · Mathematics 2025-01-03 Félix Cabello Sánchez

Some aspects of analysis on disconnected open subsets of the plane with connected fractal boundary are discussed.

Classical Analysis and ODEs · Mathematics 2007-10-02 Stephen Semmes

We construct a Hereditarily Indecomposable Banach space $\eqs_d$ with a Schauder basis \seq{e}{n} on which there exist strictly singular non-compact diagonal operators. Moreover, the space $\mc{L}_{\diag}(\eqs_d)$ of diagonal operators with…

Functional Analysis · Mathematics 2008-07-16 Spiros A. Argyros , Irene Deliyanni , Andreas G. Tolias

Several recent papers investigated unbounded convergences in Banach lattices. Combine all unbounded convergences, including unbounded order (norm, absolute weak, absolute weak*) convergence, we characterize L-weakly compact sets, L-weakly…

Functional Analysis · Mathematics 2021-04-06 Zhangjun Wang , Zili Chen , Jinxi Chen

We study Birkhoff-James orthogonality of bounded linear operators on complex Banach spaces and obtain a complete characterization of the same. By means of introducing new definitions, we illustrate that it is possible in the complex case,…

Functional Analysis · Mathematics 2024-07-30 Kallol Paul , Debmalya Sain , Arpita Mal , Kalidas Mandal

We analyse possibility to extend a quantum operation (sub-unital normal CP linear map on the algebra $B(H)$ of bounded operators on a separable Hilbert space $H$) to the space of all operators on $H$ relatively bounded w.r.t. a given…

Mathematical Physics · Physics 2020-11-16 M. E. Shirokov

The notion of decomposable operators acting between distinct $L^p$-direct integrals of Banach spaces is introduced. We show that these operators generalize the composition operator, in sense that a mapping is replaced by a binary relation.…

Functional Analysis · Mathematics 2024-11-26 Nikita Evseev , Alexander Menovschikov

We study the spectrum of spherically symmetric Dirac operators in three-dimensional space with potentials tending to infinity at infinity under weak regularity assumptions. We prove that purely absolutely continuous spectrum covers the…

Spectral Theory · Mathematics 2007-05-23 Karl Michael Schmidt , Osanobu Yamada