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We study the notions of acs, luacs and uacs Banach spaces which were introduced by V. Kadets et al. in 2000 and form common generalisations of the usual rotundity and smoothness properties of Banach spaces. In particular, we are interested…

Functional Analysis · Mathematics 2013-02-28 Jan-David Hardtke

We present some new results on the symmetric Kottman's constant $K^s(X)$ of a Banach space $X$ and its relationship with the Kottman constant. We show that $K^s(X)>1$, for every infinite-dimensional Banach space, thereby solving a problem…

Functional Analysis · Mathematics 2020-06-09 Tommaso Russo

The convex-transitivity property can be seen as a convex generalization of the almost transitive (or quasi-isotropic) group action of the isometry group of a Banach space on its unit sphere. We will show that certain Banach algebras,…

Operator Algebras · Mathematics 2015-01-23 María J. Martín , Jarno Talponen

It is proved that there exist complemented subspaces of countable topological products (locally convex direct sums) of Banach spaces which cannot be represented as topological products (locally convex direct sums) of Banach spaces. (This is…

Functional Analysis · Mathematics 2010-09-07 Mikhail I. Ostrovskii

We prove that if X is an infinite dimensional Banach lattice with a weak unit then there exists a probability space (Omega, Sigma,mu) so that the unit sphere S(L_1(Omega, Sigma, mu) is uniformly homeomorphic to the unit sphere S(X) if and…

Functional Analysis · Mathematics 2016-09-06 Fouad Chaatit

Several new characterizations of Banach spaces containing a subspace isomorphic to $\ell^1$, are obtained. These are applied to the question of when $\ell^1$ embeds in the injective tensor product of two Banach spaces.

Functional Analysis · Mathematics 2007-11-01 Haskell P. Rosenthal

For each ordinal $\xi$ and each $1<p<\infty$, we offer a natural, ismorphic characterization of those spaces and operators which admit an equivalent $\xi$-$p$-asymptotically uniformly smooth norm. We also introduce the notion of…

Functional Analysis · Mathematics 2017-06-06 R. M. Causey

The primary objective of this paper is to develop methodologies for investigating Schwarz type lemmas and to present their applications in Banach spaces. First, we improve upon the main results obtained by Osserman [Proc. Am. Math. Soc.…

Complex Variables · Mathematics 2026-05-19 Shaolin Chen , Hidetaka Hamada , Megha Kundathil , Ramakrishnan Vijayakumar

We extend the result of B. Cascales at al. about expand-contract plasticity of the unit ball of strictly convex Banach space to those spaces whose unit ball is the union of all its finite-dimensional polyhedral extreme subsets. We also…

Functional Analysis · Mathematics 2018-08-28 Carlos Angosto , Vladimir Kadets , Olesia Zavarzina

For each ordinal $\alpha< \omega_1$, we prove the existence of a separable, reflexive Banach space with a basis and Szlenk index $\omega^{\alpha+1}$ which is universal for the class of separable, reflexive Banach spaces $X$ such that the…

Functional Analysis · Mathematics 2013-08-27 Ryan Causey

We study the general measures of non-compactness defined on subsets of a dual Banach space, their associated derivations and their $\omega$-iterates. We introduce the notions of convexifiable and sublinear measure of non-compactness and…

Functional Analysis · Mathematics 2016-10-18 Gilles Lancien , Antonin Procházka , Matias Raja

It is known that a Banach space contains an isomorphic copy of $c_0$ if, and only if, it can be equivalently renormed to be almost square. We introduce and study transfinite versions of almost square Banach spaces with the purpose to relate…

Functional Analysis · Mathematics 2022-04-29 Antonio Avilés , Stefano Ciaci , Johann Langemets , Aleksei Lissitsin , Abraham Rueda Zoca

We provide some new consequences on the Lipschitz numerical radius and index which were introduced recently. More precisely, we give some renorming results on the Lipschitz numerical index, introduce a concept of Lipschitz numerical radius…

Functional Analysis · Mathematics 2021-10-27 Geunsu Choi , Mingu Jung , Hyung-Joon Tag

In the article is introduced a new class of Banach spaces that are called sub B-convex. Namely, a Banach space X is said to be B -convex if it may be represented as a direct sum l_1+ W, where W is B-convex. It will be shown that any…

Functional Analysis · Mathematics 2007-05-23 Eugene Tokarev

We study those Banach spaces $X$ for which $S_X$ does not admit a finite $\eps$-net consisting of elements of $S_X$ for any $\eps < 2$. We give characterisations of this class of spaces in terms of $\ell_1$-type sequences and in terms of…

Functional Analysis · Mathematics 2015-07-16 Vladimir Kadets , Varvara Shepelska , Dirk Werner

Classes of Banach spaces that are finitely, strongly finitely or elementary equivalent are introduced. On sets of these classes topologies are defined in such a way that sets of defined classes become compact totally disconnected…

Functional Analysis · Mathematics 2007-05-23 Eugene Tokarev

We prove that if X is an infinite-dimensional Banach space with C^p smooth partitions of unity, then X and X\K are C^p diffeomorphic, for every weakly compact subset K of X.

Functional Analysis · Mathematics 2007-05-23 Daniel Azagra , Alejandro Montesinos

We examine the group of isometries of the open unit ball of a complex Banach space of certain bounded linear operators equipped with the Carath\'eodory metric. Therein we obtain a charactrization of the normal isometries in terms of their…

Functional Analysis · Mathematics 2023-03-08 Rachna Aggarwal , Krishnendu Gongopadhyay , Mukund Madhav Mishra

In this note we study the endomorphisms of certain Banach algebras of infinitely differentiable functions on compact plane sets, associated with weight sequences M. These algebras were originally studied by Dales, Davie and McClure. In a…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein , Herbert Kamowitz

In this paper, we study quasim\"obius invariance of uniform domains in Banach spaces. We first investigate implications of certain geometric properties of domains in Banach spaces, such as the (diameter) uniformity, the $\delta$-uniformity…

Complex Variables · Mathematics 2020-07-14 Qingshan Zhou , Antti Rasila