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We formalize the observation that the same summability methods converge in a Banach space $X$ and its dual $X^*$. At the same time we determine conditions under which these methods converge in the weak and weak*-topologies on $X$ and $X^*$…

Functional Analysis · Mathematics 2023-02-15 Soumitra Ghara , Javad Mashreghi , Thomas Ransford

We identify a class of smooth Banach *-algebras that are differential subalgebras of commutative C*-algebras whose openness of multiplication is completely determined by the topological stable rank of the target C*-algebra. We then show…

Operator Algebras · Mathematics 2024-11-27 Tomasz Kania , Natalia Maślany

This paper deals with the interplay of the geometry of the norm and the weak topology in Banach spaces. Both dual and intrinsic connections between weak forms of rotundity and smoothness ared discussed. Weakly exposed points, weakly locally…

Functional Analysis · Mathematics 2007-06-25 J. Talponen

We generalise Wigner's theorem to its most general form possible for B(h) in the sense of completely characterising those vector state transformations of B(h) that appear as restrictions of duals of linear operators on B(h). We then use…

Operator Algebras · Mathematics 2007-05-23 Louis Labuschagne

It is shown that if $A$ is an analytic class of separable Banach spaces with separable dual, then the set $A^*=\{Y:\exists X\in A \text{with} Y\cong X^*\}$ is analytic. The corresponding result for pre-duals is false.

Functional Analysis · Mathematics 2011-05-11 Pandelis Dodos

We introduce and study Banach spaces which have property CWO, i.e., every finite convex combination of relatively weakly open subsets of their unit ball is open in the relative weak topology of the unit ball. Stability results of such…

Functional Analysis · Mathematics 2018-06-29 Trond Arnold Abrahamsen , Julio Becerra Guerrero , Rainis Haller , Vegard Lima , Märt Põldvere

We prove a basic property of continuous multilinear mappings between topological vector spaces, from which we derive an easy proof of the fact that a multilinear mapping (and a polynomial) between topological vector spaces is weakly…

Functional Analysis · Mathematics 2016-09-06 Manuel Gonzalez , Joaquin M. Gutierrez

We first prove that every AF-algebra is weakly central, thereby resolving a question left open by Archbold--Gogi\'c. We then establish a new characterization of weak centrality for unital $C^*$-algebras in terms of $C(X)$-algebras. The…

Operator Algebras · Mathematics 2026-01-23 Bharat Talwar , Prahlad Vaidyanathan , Stefan Wagner

It is shown that all the approximately finite dimensional C*-algebras which are not of Type I are isomorphic as Banach spaces. This generalises the matroid case given previously by Arazy. Analogous results are obtained for various families…

funct-an · Mathematics 2008-02-03 S. C. Power

We investigate certain envelopes of open sets in dual Banach spaces which are related to extending holomorphic functions. We give a variety of examples of absolutely convex sets showing that the extension is in many cases not possible. We…

Functional Analysis · Mathematics 2010-05-10 D. Garcia , O. F. K. Kalenda , M. Maestre

This paper concerns the problem of integrability of non closed distributions on Banach manifolds. We introduce the notion of weak distribution and we look for conditions under which these distributions admit weak integral submanifolds. We…

Differential Geometry · Mathematics 2011-12-06 Fernand Pelletier

We prove that every weak-local derivation on a C$^*$-algebra is continuous, and the same conclusion remains valid for weak$^*$-local derivations on von Neumann algebras. We further show that weak-local derivations on C$^*$-algebras and…

Operator Algebras · Mathematics 2014-12-01 Ahlem Ben Ali Essaleh , Antonio M. Peralta , María Isabel Ramírez

Let $F$ be an ordered topological vector space (over $\mathbb{R}$) whose positive cone $F_+$ is weakly closed, and let $E \subseteq F$ be a subspace. We prove that the set of positive continuous linear functionals on $E$ that can be…

Functional Analysis · Mathematics 2021-04-29 Josse van Dobben de Bruyn

Given a separable Banach space $E$, we construct an extremely non-complex Banach space (i.e. a space satisfying that $\|Id + T^2\|=1+\|T^2\|$ for every bounded linear operator $T$ on it) whose dual contains $E^*$ as an $L$-summand. We also…

Functional Analysis · Mathematics 2010-01-29 Piotr Koszmider , Miguel Martin , Javier Meri

Let $A$ be a Banach algebra and $A^{**}$ be the second dual of it. We define $\tilde{Z}_1(A^{**})$ as a weak topological center of $A^{**}$ with respect to first Arens product and we will find some relations between this concept and the…

Functional Analysis · Mathematics 2010-07-01 Kazem Haghnejad Azar

We consider a Banach algebra $A$ with the property that, roughly speaking, sufficiently many irreducible representations of $A$ on nontrivial Banach spaces do not vanish on all square zero elements. The class of Banach algebras with this…

Operator Algebras · Mathematics 2013-07-09 J. Alaminos , M. Brešar , J. Extremera , Š. Špenko , A. R. Villena

A well-known result of R. Pol states that a Banach space $X$ has property ($\mathcal{C}$) of Corson if and only if every point in the weak*-closure of any convex set $C \subseteq B_{X^*}$ is actually in the weak*-closure of a countable…

Functional Analysis · Mathematics 2023-03-06 Gonzalo Martínez-Cervantes , Alejandro Poveda

Let $G$ be a locally compact group, and let $WAP(G)$ denote the space of weakly almost periodic functions on $G$. We show that, if $G$ is a $[SIN]$-group, but not compact, then the dual Banach algebra $WAP(G)^\ast$ does not have a normal,…

Functional Analysis · Mathematics 2007-05-23 Volker Runde

We show that the predual of a JBW$^*$-triple has the weak Banach-Saks property, that is, reflexive subspaces of a JBW$^*$-triple predual are super-reflexive. We also prove that JBW$^*$-triple preduals satisfy the Koml\'os property (which…

Operator Algebras · Mathematics 2015-05-21 Antonio M. Peralta , Hermann Pfitzner

We introduce an ordinal index which characterizes weak compactness of operators between Banach spaces. We study when classes consisting of operators having bounded index form a closed ideal, the distinctness of the classes, and the…

Functional Analysis · Mathematics 2015-08-25 Ryan M. Causey