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We give a sufficient condition for a pair of Banach spaces $(X,Y)$ to have the following property: whenever $W_1 \subseteq X$ and $W_2 \subseteq Y$ are sets such that $\{x\otimes y: \, x\in W_1, \, y\in W_2\}$ is weakly precompact in the…

Functional Analysis · Mathematics 2023-05-11 José Rodríguez , Abraham Rueda Zoca

We prove that, given two Banach spaces $X$ and $Y$ and bounded, closed convex sets $C\subseteq X$ and $D\subseteq Y$, if a nonzero element $z\in \overline{\mathrm{co}}(C\otimes D)\subseteq X\widehat{\otimes}_\pi Y$ is a preserved extreme…

Functional Analysis · Mathematics 2022-12-05 Luis C. García-Lirola , Guillaume Grelier , Gonzalo Martínez-Cervantes , Abraham Rueda Zoca

We study the property of being strongly weakly compactly generated (and some relatives) in projective tensor products of Banach spaces. Our main result is as follows. Let $1<p,q<\infty$ be such that $1/p+1/q\geq 1$. Let $X$ (resp., $Y$) be…

Functional Analysis · Mathematics 2022-06-20 José Rodríguez

We prove that, under certain conditions, uniform weak mixing (to zero) of the bounded sequences in Banach space implies uniform weak mixing of its tensor product. Moreover, we prove that ergodicity of tensor product of the sequences in…

Functional Analysis · Mathematics 2012-01-23 Farrukh Mukhamedov

In these notes, we study nonlinear embeddings between Banach spaces which are also weakly sequentially continuous. In particular, our main result implies that if a Banach space $X$ coarsely (resp. uniformly) embeds into a Banach space $Y$…

Functional Analysis · Mathematics 2017-10-24 Bruno de Mendonça Braga

For $C^{*}$-algebras $A$ and $B$, the operator space projective tensor product $A\hat{\otimes}B$ and the Banach space projective tensor product $A\otimes_{\gamma}B$ are shown to be symmetric. We also show that $A\hat{\otimes}B$ is weakly…

Operator Algebras · Mathematics 2012-05-09 Ajay Kumar , Vandana Rajpal

Let $X$ be a reflexive Banach space such that for any $x \ne 0$ the set $$ \{x^* \in X^*: \text {$\|x^*\|=1$ and $x^*(x)=\|x\|$}\} $$ is compact. We prove that any unrestricted product of of a finite number of $(W)$ contractions on $X$…

Functional Analysis · Mathematics 2016-09-06 P. K. Lin

The aim of this note is to prove that, given two superreflexive Banach spaces $X$ and $Y$, then $X\widehat{\otimes}_\pi Y$ is superreflexive if and only if either $X$ or $Y$ is finite-dimensional. In a similar way, we prove that…

Functional Analysis · Mathematics 2024-10-01 Abraham Rueda Zoca

The main results of the paper: {\bf (1)} The dual Banach space $X^*$ contains a linear subspace $A\subset X^*$ such that the set $A^{(1)}$ of all limits of weak$^*$ convergent bounded nets in $A$ is a proper norm-dense subset of $X^*$ if…

Functional Analysis · Mathematics 2013-02-26 Mikhail I. Ostrovskii

Let $X$ be a Banach space and $Y \subseteq X$ be a closed subspace. We prove that if the quotient $X/Y$ is weakly Lindel\"{o}f determined or weak Asplund, then for every $w^*$-convergent sequence $(y_n^*)_{n\in \mathbb N}$ in $Y^*$ there…

Functional Analysis · Mathematics 2021-03-08 G. Martínez-Cervantes , J. Rodríguez

A topological space is said to be sequential if every sequentially closed subspace is closed. We consider Banach spaces with weak*-sequential dual ball. In particular, we show that if $X$ is a Banach space with weak*-sequentially compact…

Functional Analysis · Mathematics 2016-12-20 Gonzalo Martínez-Cervantes

A nonempty closed convex bounded subset $C$ of a Banach space is said to have the weak approximate fixed point property if for every continuous map $f:C\to C$ there is a sequence $\{x_n\}$ in $C$ such that $x_n-f(x_n)$ converge weakly to 0.…

Functional Analysis · Mathematics 2011-03-18 Ondřej F. K. Kalenda

Given two Banach spaces $X$ and $Y$, we analyze when the projective tensor product $X\widehat{\otimes}_\pi Y$ has Corson's property (C) or is weakly Lindel\"of determined (WLD), subspace of a weakly compactly generated (WCG) space or…

Functional Analysis · Mathematics 2022-02-02 Antonio Avilés , Gonzalo Martínez-Cervantes , José Rodríguez , Abraham Rueda Zoca

We show by a ridiculously simple argument that, for any norm on the tensor product of vector spaces, every element of the completion can be represented as a convergent series of elementary tensors.

Functional Analysis · Mathematics 2025-06-27 Jochen Wengenroth

We show that for a Banach algebra $A$ with a bounded approximate identity, the amenability of the projective tensor product of A with A, the amenability of the projective tensor product of A with A^{op}and the amenability of A are…

Functional Analysis · Mathematics 2010-12-08 Miad Makareh Shireh

We prove that if a unital Banach algebra $A$ is the dual of a Banach space $\pd{A}$, then the set of weak* continuous states is weak* dense in the set of all states on $A$. Further, weak* continuous states linearly span $\pd{A}$.

Functional Analysis · Mathematics 2008-08-15 Bojan Magajna

In this paper we analyse when every element of $X\widehat{\otimes}_\pi Y$ attains its projective norm. We prove that this is the case if $X$ is the dual of a subspace of a predual of an $\ell_1(I)$ space and $Y$ is $1$-complemented in its…

Functional Analysis · Mathematics 2024-07-16 Luis C. García-Lirola , Juan Guerrero-Viu , Abraham Rueda Zoca

We provide sufficient conditions for a Banach space Y to be weakly sequentially complete. These conditions are expressed in terms of the existence of directional derivatives for cone convex mappings with values in Y .

Optimization and Control · Mathematics 2016-02-20 E. M. Bednarczuk , K. Leśniewski

We show that every Banach space in which weakly compact sets are super weakly compact in automatically weakly sequentially complete answering a question by Silber (2024). In the proof we show how to build a weakly compact set which is not…

Functional Analysis · Mathematics 2025-01-29 Zdeněk Silber

We obtain new progresses about the diameter two property and the Daugavet property in tensor product spaces. Namely, the main results of the paper are: -If $X^*$ has the WODP, then $X\widehat{\otimes}_\varepsilon Y$ has the DD2P for any…

Functional Analysis · Mathematics 2024-08-01 Abraham Rueda Zoca
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