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We give a metric characterisation of when the Lipschitz-free space over a separable ultrametric space is a dual Banach space. In the case where the Lipschitz-free space has a predual, we show that this predual is M-embedded if and only if…

Functional Analysis · Mathematics 2025-10-13 Trond A. Abrahamsen , Vegard Lima , Andre Ostrak

We study the set $\operatorname{SNA}(M,Y)$ of those Lipschitz maps from a (complete pointed) metric space $M$ to a Banach space $Y$ which (strongly) attain their Lipschitz norm (i.e.\ the supremum defining the Lipschitz norm is a maximum).…

Functional Analysis · Mathematics 2019-01-09 Bernardo Cascales , Rafa Chiclana , Luis Garcia-Lirola , Miguel Martin , Abraham Rueda Zoca

The geometric notion of huskability initiated and developed in [B3], [BR] ,[EW], [GM] was subsequently extensively studied in the context of dentability and Radon Nikodym Property in [GGMS]. In this work, we introduce a new geometric…

Functional Analysis · Mathematics 2021-08-06 Sudeshna Basu , Susmita Seal

We introduce and study multivariate generalizations of the classical BV spaces of Jordan, F. Riesz and Wiener. The family of the introduced spaces contains or is intimately related to a considerable class of function spaces of modern…

Functional Analysis · Mathematics 2018-06-26 Alexander Brudnyi , Yuri Brudnyi

Spaces of homogeneous polynomials on a Banach space are frequently equipped with quasinorms instead of norms. In this paper we develop a technique to replace the original quasi-norm by a norm in a dual preserving way, in the sense that the…

Functional Analysis · Mathematics 2018-04-02 V. V. Favaro , D. Pellegrino

In this note the following is proved. Separable L-embedded spaces - that is separable Banach spaces which are complemented in their biduals such that the norm between the two complementary subspaces is additive - have property (X) which, by…

Functional Analysis · Mathematics 2007-05-23 Hermann Pfitzner

We show that finite dimensional Banach spaces fail to be uniformly non locally almost square. Moreover, we construct an equivalent almost square bidual norm on $\ell_\infty.$ As a consequence we get that every dual Banach space containing…

Functional Analysis · Mathematics 2020-03-10 Trond A. Abrahamsen , Petr Hájek , Stanimir Troyanski

Geometric quantiles are location parameters which extend classical univariate quantiles to normed spaces (possibly infinite-dimensional) and which include the geometric median as a special case. The infinite-dimensional setting is highly…

Statistics Theory · Mathematics 2026-02-13 Gabriel Romon

A Banach space $X$ has the $Mazur$-$Ulam$ $property$ if any isometry from the unit sphere of $X$ onto the unit sphere of any other Banach space $Y$ extends to a linear isometry of the Banach spaces $X,Y$. A Banach space $X$ is called…

Functional Analysis · Mathematics 2021-11-01 Taras Banakh , Javier Cabello Sánchez

We prove the existence of a linear isometric correspondence between the Banach space of all symmetric orthogonal forms on a JB$^*$-algebra $\mathcal{J}$ and the Banach space of all purely Jordan generalized derivations from $\mathcal{J}$…

Operator Algebras · Mathematics 2014-11-12 Fatmah B. Jamjoom , Antonio M. Peralta , Akhlaq A. Siddiqui

In this paper we present new characterizations of Banach spaces whose duals are isomorphic to $l_{1}(\Gamma),$ extending results of Stegall, Lewis-Stegall and Cilia-D'Anna-Guti\'{e}rrez.

Functional Analysis · Mathematics 2007-05-23 Daniel M. Pellegrino

We study Banach spaces with a weak stable unit ball, that is Banach spaces where every convex combination of relatively weakly open subsets in its unit ball is again a relatively weakly open subset in its unit ball. It is proved that the…

Functional Analysis · Mathematics 2021-07-27 Ginés López-Pérez , Rubén Medina

A Banach space $X$ has \textit{property $(K)$}, whenever every weak* null sequence in the dual space admits a convex block subsequence $(f_{n})_{n=1}^\infty$ so that $\langle f_{n},x_{n}\rangle\to 0$ as $n\to \infty$ for every weakly null…

Functional Analysis · Mathematics 2021-02-02 Dongyang Chen , Tomasz Kania , Yingbin Ruan

In this article, we establish the existence of a norm-one projection from the space of all \emph{two-Lipschitz} operators onto the space of all bounded bilinear operators under certain conditions on the corresponding codomain spaces, using…

Functional Analysis · Mathematics 2025-12-08 Arindam Mandal

In this paper we study ways to establish when a Banach space can be identified as the dual or the double dual of another Banach space. To obtain these results, we relate these spaces with other, concrete Banach spaces - tipically $\ell^1$…

Functional Analysis · Mathematics 2020-09-29 Luigi D'Onofrio , Gianluigi Manzo , Carlo Sbordone , Roberta Schiattarella

We characterize the points of $\left\|\cdot\right\|$-$w^*$ continuity of dual maps, turning out to be the smooth points. We prove that a Banach space has the Schur property if and only if it has the Dunford-Pettis property and there exists…

Functional Analysis · Mathematics 2015-10-07 Francisco J. García-Pacheco , Alejandro Miralles , Daniele Puglisi

Given a Banach space X and a subspace Y, the pair (X,Y) is said to have the approximation property (AP) provided there is a net of finite rank bounded linear operators on X all of which leave the subspace Y invariant such that the net…

Functional Analysis · Mathematics 2015-08-07 T. Figiel , W. B. Johnson

The maximal roundness of a metric space is a quantity that arose in the study of embeddings and renormings. In the setting of Banach spaces, it was shown by Enflo that roundness takes on a much simpler form. In this paper we provide simple…

Functional Analysis · Mathematics 2021-09-16 Alireza Amini-Harandi , Ian Doust , Gavin Robertson

We discuss renorming properties of the dual of a James tree space JT. We present examples of weakly Lindelof determined JT such that JT* admits neither strictly convex nor Kadec renorming and of weakly compactly generated JT such that JT*…

Functional Analysis · Mathematics 2009-03-03 Antonio Avilés

A hypercomplex structure $(I,J,K)$ on a manifold $M$ is said to be $C^\infty$-pure-and-full if the Dolbeault cohomology $H^{2,0}_{\partial}(M,I)$ is the direct sum of two natural subgroups called the $\bar{J}$-invariant and the…

Differential Geometry · Mathematics 2023-03-10 Mehdi Lejmi , Nicoletta Tardini