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We give a characterization of the operators on the injective tensor product $E \hat{\otimes}_\varepsilon X$ for any separable Banach space $E$ and any (non-separable) Banach space $X$ with few operators, in the sense that any operator $T: X…

Functional Analysis · Mathematics 2025-09-23 Antonio Acuaviva

In this article, concepts of well- and ill-posedness for linear operators in Hilbert and Banach spaces are discussed. While these concepts are well understood in Hilbert spaces, this is not the case in Banach spaces, as there are several…

Functional Analysis · Mathematics 2025-05-20 Bernd Hofmann , Stefan Kindermann

We find that the perfect distinguishability of two quantum operations by a parallel scheme depends only on an operator subspace generated from their Choi-Kraus operators. We further show that any operator subspace can be obtained from two…

Quantum Physics · Physics 2017-01-31 Runyao Duan , Cheng Guo , Chi-Kwong Li , Yinan Li

We consider 1-complemented subspaces (ranges of contractive projections) of vector-valued spaces $\ell_p(X)$, where $X$ is a Banach space with a 1-unconditional basis and $p \in (1,2)\cup (2,\infty)$. If the norm of $X$ is twice…

Functional Analysis · Mathematics 2007-05-23 Bas Lemmens , Beata Randrianantoanina , Onno van Gaans

We introduce the notions of almost Lipschitz embeddability and nearly isometric embeddability. We prove that for $p\in [1,\infty]$, every proper subset of $L_p$ is almost Lipschitzly embeddable into a Banach space $X$ if and only if $X$…

Metric Geometry · Mathematics 2017-09-27 Florent Baudier , Gilles Lancien

Generalizing Pisier's idea, we introduce a Hilbertian matrix cross normed space associated with a pair of symmetric normed ideals. When the two ideals coincide, we show that our construction gives an operator space if and only if the ideal…

Operator Algebras · Mathematics 2007-05-23 Takahiro Ohta

We consider the standard quantum logic ${\mathcal L}(H)$ associated to a complex Hilbert space $H$, i.e. the lattice of closed subspaces of $H$ together with the orthogonal complementation. The orthogonality and compatibility relations are…

Functional Analysis · Mathematics 2017-02-13 Mark Pankov

This paper is focused on some properties of paramonotone operators on Banach spaces and their application to certain feasibility problems for convex sets in a Hilbert space and convex systems in the Euclidean space. In particular, it shows…

Optimization and Control · Mathematics 2023-07-04 J. Camacho , M. J. Cánovas , J. E. Martínez-Legaz , J. Parra

We study two subspace systems in a separable infinite-dimensional Hilbert space up to (bounded) isomorphism. One of the main result of this paper is the following: Isomorphism classes of two subspace systems given by graphs of bounded…

Functional Analysis · Mathematics 2018-10-15 Masatoshi Enomoto , Yasuo Watatani

In this paper, first we study surjective isometries (not necessarily linear) between completely regular subspaces $A$ and $B$ of $C_0(X,E)$ and $C_0(Y,F)$ where $X$ and $Y$ are locally compact Hausdorff spaces and $E$ and $F$ are normed…

Functional Analysis · Mathematics 2020-03-04 Mojtaba Mojahedi , Fereshteh Sady

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

In this brief note we describe relations between the well known notion of a relatively bounded operator and the operator E-norms considered in [arXiv:1806.05668]. We show that the set of all $\sqrt{G}$-bounded operators equipped with the…

Functional Analysis · Mathematics 2018-11-27 M. E. Shirokov

First, we solve a crucial problem under which conditions increasing uniform K-monotonicity is equivalent to lower locally uniform K-monotonicity. Next, we investigate properties of substochastic operators on $L^1+L^\infty$ with…

Functional Analysis · Mathematics 2024-06-13 Maciej Ciesielski , Grzegorz Lewicki

Let $H_1$ and $H_2$ be complex Hilbert spaces and $T:H_1\rightarrow H_2$ be a bounded linear operator. We say $T$ to be norm attaining, if there exists $x\in H_1$ with $\|x\|=1$ such that $\|Tx\|=\|T\|$. If for every closed subspace $M$ of…

Functional Analysis · Mathematics 2022-04-13 G. Ramesh , Shanola S. Sequeira

We give sufficient conditions on a Banach space $X$ which ensure that $\ell_{\infty}$ embeds in $\mathcal{L}(X)$, the space of all operators on $X$. We say that a basic sequence $(e_n)$ is quasisubsymmetric if for any two increasing…

Functional Analysis · Mathematics 2007-05-23 G. Androulakis , K. Beanland , S. J. Dilworth , F. Sanacory

In this paper we study shorted operators relative to two different subspaces, for bounded operators on infinite dimensional Hilbert spaces. We define two notions of complementability in the sense of Ando for operators, and study the…

Functional Analysis · Mathematics 2007-05-23 Jorge Antezana , Gustavo Corach , Demetrio Stojanoff

An operator $T$ on a Banach space is said to be of chain $N$ if there exist non-scalar operators $S_1,...,S_{N-1}$ and a non-zero compact $K$ such that $$T \leftrightarrow S_1 \leftrightarrow S_2 \leftrightarrow ...\leftrightarrow S_{N-1}…

Functional Analysis · Mathematics 2025-07-22 Tomasz Szczepanski

We investigate the interplay among three key properties of bounded linear operators between Banach spaces: the Bhatia-\v{S}emrl property, strong subdifferentiability and the condition that the essential norm is strictly less than the…

Functional Analysis · Mathematics 2025-12-18 C. R. Jayanarayanan , Rishit R Rajpopat

We investigate the space of bounded linear operators on a Banach space equipped with a norm which is equivalent to the operator norm such that the subspace of compact operators is an M-ideal. In particular, we observe that the space of…

Functional Analysis · Mathematics 2025-02-19 Manwook Han , Sun Kwang Kim

We present some properties of orthogonality and relate them with support disjoint and norm inequalities in p Schatten ideals. In addition, we investigate the problem of characterization of norm parallelism for bounded linear operators. We…

Functional Analysis · Mathematics 2021-07-23 T. Bottazzi , C. Conde , M. S. Moslehian , P. Wojcik , A. Zamani