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We show that for "most" compact non metrizable spaces, the unit ball of the Banach space C(K) contains an uncountable 2-equilateral set. We also give examples of compact non metrizable spaces K such that the minimum cardinality of a maximal…

Functional Analysis · Mathematics 2015-01-27 S. K. Mercourakis , G. Vassiliadis

Given a compact Hausdorff space $K$ we consider the Banach space of real continuous functions $C(K^n)$ or equivalently the $n$-fold injective tensor product $\hat\bigotimes_{\varepsilon}C(K)$ or the Banach space of vector valued continuous…

Functional Analysis · Mathematics 2015-01-16 Leandro Candido , Piotr Koszmider

We show that any Banach space contains a continuum of non isomorphic subspaces or a minimal subspace. We define an ergodic Banach space $X$ as a space such that $E_0$ Borel reduces to isomorphism on the set of subspaces of $X$, and show…

Functional Analysis · Mathematics 2014-02-25 Valentin Ferenczi , Christian Rosendal

We prove that several classical Banach space properties are equivalent to separability for the class of Lipschitz-free spaces, including Corson's property ($\mathcal{C}$), Talponen's Countable Separation Property, or being a G\^ateaux…

Functional Analysis · Mathematics 2024-04-08 Ramón J. Aliaga , Guillaume Grelier , Antonín Procházka

A compact space is said to be weakly Radon-Nikod\'ym if it is homeomorphic to a weak*-compact subset of the dual of a Banach space not containing an isomorphic copy of $\ell_1$. In this work we provide an example of a continuous image of a…

Functional Analysis · Mathematics 2015-09-18 Gonzalo Martínez-Cervantes

Assuming that there is a stationary set in $\omega_{2}$ of ordinals of countable cofinality that does not reflect, we prove that there exists a compact space which is not Corson compact and whose all continuous images of weight at most…

General Topology · Mathematics 2016-08-09 Menachem Magidor , Grzegorz Plebanek

We investigate the geometry of $C(K,X)$ and $\ell_{\infty}(X)$ spaces through complemented subspaces of the form $\left(\bigoplus_{i\in \varGamma}X_i\right)_{c_0}$. Concerning the geometry of $C(K,X)$ spaces we extend some results of D.…

Functional Analysis · Mathematics 2021-04-16 Leandro Candido

Improving a result of M. Talagrand, under the assumption of a weak form of Martin's axiom, we construct a totally disconnected compact Hausdorff space $K$ such that the Banach space $C(K)$ of continuous real-valued functions on $K$ is a…

Functional Analysis · Mathematics 2024-04-19 Damian Sobota , Lyubomyr Zdomskyy

Under the assumption that the continuum c is a regular cardinal, we prove the existence and uniqueness of a Boolean algebra B of size c defined by sharing the main structural properties that P(N)/fin has under CH and in the aleph2-Cohen…

Logic · Mathematics 2014-06-30 Antonio Avilés , Christina Brech

For a Banach space $X$ denote by $\mathcal{L}(X)$ the algebra of bounded linear operators on $X$, by $\mathcal{K}(X)$ the compact operator ideal on $X$, and by $Cal(X) = \mathcal{L}(X)/\mathcal{K}(X)$ the Calkin algebra of $X$. We prove…

Functional Analysis · Mathematics 2024-02-01 Pavlos Motakis , Anna Pelczar-Barwacz

We construct a compact linearly ordered space $K$ of weight aleph one, such that the space $C(K)$ is not isomorphic to a Banach space with a projectional resolution of the identity, while on the other hand, $K$ is a continuous image of a…

Functional Analysis · Mathematics 2012-10-23 Wieslaw Kubis

We construct an infinite dimensional Banach space of continuous functions C(K) such that every one-to-one operator on C(K) is onto.

Functional Analysis · Mathematics 2014-06-30 Antonio Avilés , Piotr Koszmider

We present an isometric version of the complementably universal Banach space $\mathbb{P}$ with a Schauder decomposition. The space $\mathbb{P}$ is isomorphic to Pe{\l}czy\'nski's space with a universal basis as well as to Kadec'…

Functional Analysis · Mathematics 2013-06-11 Joanna Garbulińska

Our main result states that, given a finite-dimensional vector space $E$, the pseudometric defined in the set of continuous quasinorms $\mathcal{Q}_0=\{\|\cdot\|:E\to\mathbb{R}\}$ as $$d(\|\cdot\|_X,\|\cdot\|_Y)=\min\{\mu:\|\cdot\|_X…

Functional Analysis · Mathematics 2021-10-15 Javier Cabello Sánchez , Daniel Morales González

We investigate the structure of conformal $C$-spaces,a class of Riemmanian manifolds which naturally arises as aconformal generalisation of the Einstein condition. A basic question is when such a structure is closed, or equivalently locally…

Differential Geometry · Mathematics 2008-06-05 A. Rod Gover , Paul-Andi Nagy

Let $X$ be a Banach space with a separable dual. We prove that $X$ embeds isomorphically into a $\cL_\infty$ space $Z$ whose dual is isomorphic to $\ell_1$. If, moreover, $U$ is a space so that $U$ and $X$ are totally incomparable, then we…

Functional Analysis · Mathematics 2010-05-17 Daniel Freeman , Edward Odell , Thomas Schlumprecht

In [8] probabilistic methods, in particular a variant of the Weak Law of Large Numbers related to the Bernoulli distribution, have been used to show that for every infinite compact spaces K and L there exists a sequence $(\mu_n)$ of…

Functional Analysis · Mathematics 2025-12-02 Jerzy Kakol , Wiesław Śliwa

We prove some generalizations of results concerning Valdivia compact spaces (equivalently spaces with a commutative retractional skeleton) to the spaces with a retractional skeleton (not necessarily commutative). Namely, we show that the…

Functional Analysis · Mathematics 2014-01-30 Marek Cuth

We prove that, for every compact spaces $K_1,K_2$ and compact group $G$, if both $K_1$ and $K_2$ map continuously onto $G$, then the Banach space $C(K_1 \times K_2)$ contains a complemented subspace isometric to the Banach space $C(G)$.…

Functional Analysis · Mathematics 2024-09-18 Grzegorz Plebanek , Jakub Rondoš , Damian Sobota

We construct a complete metric space $M$ of cardinality continuum such that every non-singleton closed separable subset of $M$ fails to be a Lipschitz retract of $M$. This provides a metric analogue to the various classical and recent…

Functional Analysis · Mathematics 2022-06-22 Petr Hájek , Andrés Quilis