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We give two examples of polyhedral Banach spaces failing all the diameter two properties, showing that there is not any connection between polyhedrality and the diameter two properties.

Functional Analysis · Mathematics 2017-03-13 Ginés López-Pérez , Abraham Rueda Zoca

We show that for real Banach spaces that are either separable or dual spaces, the Lipschitz numerical index coincides with the classical (linear) numerical index. This result provides partial evidence toward the question posed by Wang,…

Functional Analysis · Mathematics 2025-07-25 Antonio Pérez-Hernández

In this paper we investigate the distribution of zeros of Boubaker polynomials.

Functional Analysis · Mathematics 2012-11-08 Seon-Hong Kim , Lin Zhang , Karem Boubaker , Qiang Lei

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

The Banach space $\mathcal{P}({}^2X)$ of $2$-homogeneous polynomials on the Banach space $X$ can be naturally embedded in the Banach space ${{\rm Lip}_0}(B_X)$ of real-valued Lipschitz functions on $B_X$ that vanish at $0$. We investigate…

Functional Analysis · Mathematics 2022-07-15 Petr Hájek , Tommaso Russo

In this note we study Banach spaces of traces of real polynomials on $\mathbb R^n$ to compact subsets equipped with supremum norms from the point of view of Geometric Functional Analysis.

Functional Analysis · Mathematics 2014-04-23 Alexander Brudnyi

The main result: the dual of separable Banach space $X$ contains a total subspace which is not norming over any infinite dimensional subspace of $X$ if and only if $X$ has a nonquasireflexive quotient space with the strictly singular…

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

We study the numerical radius of Lipschitz operators on Banach spaces via the Lipschitz numerical index, which is an analogue of the numerical index in Banach space theory. We give a characterization of the numerical radius and obtain a…

Functional Analysis · Mathematics 2012-11-27 Ruidong Wang , Xujian Huang , Dongni Tan

We study lower bounds for the norm of the product of polynomials and their applications to the so called \emph{plank problem.} We are particularly interested in polynomials on finite dimensional Banach spaces, in which case our results…

Functional Analysis · Mathematics 2016-06-07 Daniel Carando , Damian Pinasco , Jorge Tomás Rodríguez

We present many examples of Banach spaces of linear operators and homogeneous polynomials without the approximation property, thus improving results of Dineen and Mujica [11] and Godefroy and Saphar [13].

Functional Analysis · Mathematics 2016-03-18 Sergio A. Pérez

The aim of this note is to study octahedrality in vector valued Lipschitz-free Banach spaces on a metric space under topological hypotheses on it. As a consequence, we get that the space of Lipschitz functions on a metric space valued in a…

Functional Analysis · Mathematics 2016-05-17 Julio Becerra Guerrero , Ginés López-Pérez , Abraham Rueda Zoca

In this paper structure of infinite dimensional Banach spaces is studied by using an asymptotic approach based on stabilization at infinity of finite dimensional subspaces which appear everywhere far away. This leads to notions of…

Functional Analysis · Mathematics 2016-09-06 Bernard Maurey , Vitali D. Milman , Nicole Tomczak-Jaegermann

For a certain class of algebras $\cal A$ we give a method for constructing Banach spaces $X$ such that every operator on $X$ is close to an operator in $\cal A$. This is used to produce spaces with a small amount of structure. We present…

Functional Analysis · Mathematics 2008-09-01 W. T. Gowers , B. Maurey

A Banach space contains either a minimal subspace or a continuum of incomparable subspaces. General structure results for analytic equivalence relations are applied in the context of Banach spaces to show that if $E_0$ does not reduce to…

Functional Analysis · Mathematics 2007-05-23 Christian Rosendal

The purpose of this paper is to lay the foundations for the study of the problem of when $\Ext^n(X, Y)=0$ in Banach/quasi-Banach spaces. We provide a number of examples of couples $X,Y$ so that $\Ext^n(X,Y)$ is (or is not ) $0$, including…

Functional Analysis · Mathematics 2020-05-05 Félix Cabello Sánchez , Jesús M . F. Castillo , Ricardo García

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

The aim of this note is to provide several variants of the diameter two properties for Banach spaces. We study such properties looking for the abundance of diametral points, which holds in the setting of Banach spaces with the Daugavet…

Functional Analysis · Mathematics 2016-04-18 Julio Becerra Guerrero , Ginés López Pérez , Abraham Rueda Zoca

Given a map $f \colon E \longrightarrow F$ between Banach spaces (or Banach lattices), a set $A$ of $E$-valued bounded sequences, ${\bf x} \in A$ and a vector topology $\tau$ on $F$, we investigate the existence of an infinite dimensional…

Functional Analysis · Mathematics 2025-05-07 Mikaela Aires , Geraldo Botelho

We introduce a suitable notion of asymptotic smoothness on infinite dimensional Banach spaces, and we prove that, under some structural restrictions on the space, the convex envelope of an asymptotically smooth function is asymptotically…

Functional Analysis · Mathematics 2016-04-21 Jesús A. Jaramillo , Raquel Gonzalo , Diego Yáñez

We prove the result stated in the title. This provides a first example of an infinite-dimensional Banach space whose Lipschitz free space is isomorphic to the free space of a compact set.

Functional Analysis · Mathematics 2019-11-14 Luis C. García-Lirola , Antonin Prochazka