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A Banach space $X$ is Grothendieck if the weak and the weak$^*$ convergence of sequences in the dual space $X^*$ coincide. The space $\ell^\infty$ is a classical example of a Grothendieck space due to Grothendieck. We introduce a…

Functional Analysis · Mathematics 2015-09-23 Hana Bendová

A topological space $X$ is called almost discrete, if it has precisely one nonisolated point. In this paper, we get that for a countable product $X=\prod X_i$ of almost discrete spaces $X_i$ the space $C_p(X)$ of continuous real-valued…

General Topology · Mathematics 2023-12-19 Alexander V. Osipov

The concept of the strong Pytkeev property, recently introduced by Tsaban and Zdomskyy in [32], was successfully applied to the study of the space $C_c(X)$ of all continuous real-valued functions with the compact-open topology on some…

General Topology · Mathematics 2014-12-05 S. S. Gabriyelyan , J. Kakol

Using the method of forcing we prove that consistently there is a Banach space of continuous functions on a compact Hausdorff space with the Grothendieck property and with density less than the continuum. It follows that the classical…

Functional Analysis · Mathematics 2010-05-20 Christina Brech

A Banach space is said to be Grothendieck if weak and weak$^*$ convergent sequences in the dual space coincide. This notion has been quantificated by H. Bendov\'{a}. She has proved that $\ell_\infty$ has the quantitative Grothendieck…

Functional Analysis · Mathematics 2015-11-09 Jindřich Lechner

In this paper we study the properties of P-generated spaces (by analogy with compactly generated). We prove that a regular Lindel\"of generated space with uncountable dispersion character is resolvable. It is proved that Hausdorff…

General Topology · Mathematics 2017-12-05 Maria A. Filatova , Alexander V. Osipov

In this note, we consider several notions related to the Grothendieck property. Among them, we introduce the notion "unbounded Grothendieck property" in a Banach lattice as an unbounded version of the known Grothedieck property in the…

Functional Analysis · Mathematics 2021-09-06 Omid Zabeti

In this paper, we find necessary and sufficient conditions for countable fan tightness and countable strong fan tightness of the space (briefly, $C_{p}(X,G)$) of all group-valued continuous functions endowed with the topology of pointwise…

General Topology · Mathematics 2024-12-04 Sanjay Mishra , Pankaj Pandey , Sreeram Ravindran

Generalizations of the theorems of Eberlein and Grothendieck on the precompactness of subsets of function spaces are considered: if $X$ is a countably compact space and $C_p(X)$ is a space of continuous functions in the pointwise topology…

General Topology · Mathematics 2024-11-06 E. A. Reznichenko

Countable tightness may be destroyed by countably closed forcing. We characterize the indestructibility of countable tightness under countably closed forcing by combinatorial statements similar to the ones Tall used to characterize…

General Topology · Mathematics 2013-10-22 Marion Scheepers

Given a property $P$ of subspaces of a $T_1$ space $X$, we say that $X$ is {\em $P$-bounded} iff every subspace of $X$ with property $P$ has compact closure in $X$. Here we study $P$-bounded spaces for the properties $P \in \{\omega D,…

General Topology · Mathematics 2014-07-01 István Juhász , Lajos Soukup , Zoltán Szentmiklóssy

We prove that if $K$ is a compact space and the space $P(K\times K)$ of regular probability measures on $K\times K$ has countable tightness in its $weak^*$ topology, then $L_1(\mu)$ is separable for every $\mu\in P(K)$. It has been known…

Functional Analysis · Mathematics 2014-05-13 Grzegorz Plebanek , Damian Sobota

Michael asked whether every productively Lindel\"of space is powerfully Lindel\"of. Building of work of Alster and De la Vega, assuming the Continuum Hypothesis, we show that every productively Lindel\"of space of countable tightness is…

General Topology · Mathematics 2017-11-22 Andrea Medini , Lyubomyr Zdomskyy

A Banach space $E$ has the Grothendieck property if every (linear bounded) operator from $E$ into $c_0$ is weakly compact. It is proved that, for an integer $k>1$, every $k$-homogeneous polynomial from $E$ into $c_0$ is weakly compact if…

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

Some results in C_k-theory are obtained with the use of bornologies. We investigate under which conditions the space of the continuous real functions with the compact-open topology is a productively countably tight space, which yields some…

General Topology · Mathematics 2013-12-02 Leandro Fiorini Aurichi , Renan Maneli Mezabarba

For a compact space $K$, the Banach space $C(K)$ is said to have the $\ell_1$-Grothendieck property if every weak* convergent sequence $\big\langle\mu_n\colon\ n\in\omega\big\rangle$ of functionals on $C(K)$ such that $\mu_n\in\ell_1(K)$…

Functional Analysis · Mathematics 2023-06-21 Jerzy Kąkol , Damian Sobota , Lyubomyr Zdomskyy

We introduce the strong Gelfand-Phillips property for locally convex spaces and give several characterizations of this property. We characterize the strong Gelfand-Phillips property among locally convex spaces admitting a stronger Banach…

Functional Analysis · Mathematics 2021-11-11 Taras Banakh , Saak Gabriyelyan

Given an uncountable subset $\mathcal Y$ of a nonseparable Banach space, is there an uncountable $\mathcal Z\subseteq \mathcal Y$ such that the distances between any two distinct points of $\mathcal Z$ are more or less the same? If an…

Logic · Mathematics 2024-08-12 Piotr Koszmider

We investigate the behavior of functional countability and exponential separability in products and subspaces of topological spaces. We solve a problem of Tkachuk by showing that the product of functionally countable pseudocompact spaces is…

General Topology · Mathematics 2026-03-03 Rodrigo Hernández-Gutiérrez , Santi Spadaro

We show that all finite powers of a Hausdorff space X do not contain uncountable weakly separated subspaces iff there is a c.c.c poset P such that 1_P forces that ``X is a countable union of 0-dimensional subspaces of countable weight.'' We…

Logic · Mathematics 2016-09-06 I. Juhász , Lajos Soukup , Z. Szentmiklóssy
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