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The class of spaces such that their product with every Lindel\"of space is Lindel\"of is not well-understood. We prove a number of new results concerning such productively Lindel\"of spaces with some extra property, mainly assuming the…

General Topology · Mathematics 2011-04-12 Franklin D. Tall , Boaz Tsaban

We present an internal characterization for the productively Lindel\"of property, thus answering a long-standing problem attributed to Tamano. We also present some results about the relation Alster spaces vs. productively Lindel\"of spaces.

General Topology · Mathematics 2017-12-06 Leandro F. Aurichi , Lyubomyr Zdomskyy

Lindel\"of spaces are studied in any basic Topology course. However, there are other interesting covering properties with similar behaviour, such as almost Lindel\"of, weakly Lindel\"of, and quasi-Lindel\"of, that have been considered in…

General Topology · Mathematics 2012-12-13 Petra Staynova

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

There has recently been considerable interest in productively Lindelof spaces, i.e. spaces such that their product with every Lindelof space is Lindelof. Here we make several related remarks about such spaces. Indestructible Lindelof…

General Topology · Mathematics 2012-10-31 Haosui Duanmu , Franklin D. Tall , Lyubomyr Zdomskyy

In this paper we introduce and study the notion of pairwise weakly Lindelof bitopological spaces and obtain some results. Further, we also study the pairwise weakly Lindelof subspaces and subsets, investigate some of their properties and…

General Topology · Mathematics 2009-01-29 Adem Kilicman , Zabidin Salleh

We give easy proofs that a) the Continuum Hypothesis implies that if the product of X with every Lindelof space is Lindelof, then X is a D-space, and b) Borel's Conjecture implies every Rothberger space is Hurewicz.

General Topology · Mathematics 2011-04-19 Franklin D. Tall

We prove that under certain set-theoretic assumptions every productively Lindel\"of space has the Hurewicz covering property, thus improving upon some earlier results of Aurichi and Tall.

General Topology · Mathematics 2014-06-04 Dušan Repovš , Lyubomyr Zdomskyy

We discuss relationships in Lindelof spaces among the properties "indestructible", "productive", "D", and related properties.

General Topology · Mathematics 2011-04-15 Franklin D. Tall , Leandro F. Aurichi

We study productive properties of gamma spaces, and their relation to other, classic and modern, selective covering properties. Among other things, we prove the following results: 1. Solving a problem of F. Jordan, we show that for every…

Logic · Mathematics 2018-10-11 Arnold W. Miller , Boaz Tsaban , Lyubomyr Zdomskyy

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

We prove that assuming $\mathfrak{b}=\mathfrak{d}$, in the class of hereditarily Lindel\"of spaces, each productively Scheepers space is productively Hurewicz. The above statement remains true in the class of all general topological spaces…

General Topology · Mathematics 2026-02-19 Marta Kładź-Duda , Piotr Szewczak , Lyubomyr Zdomskyy

A dual pair formulation for asymmetric locally convex spaces is developed that strictly generalises the ordinary vector space setting. The concept of a polar topology carries over to the asymmetric case and some familiar results are…

General Topology · Mathematics 2026-02-24 Jobst Ziebell

The main purpose of this note is to prove that the product of a cellular Lindelof space with a space of countable spread need not be cellular-Lindelof.

General Topology · Mathematics 2020-12-07 Alan Dow , Robert M. Stephenson

In this paper, authors prove that if $X$ is a weak Asplund space, then the space $X\times R$ is a weak Asplund space. Thus the author definitely answered an open problem raised by D.G. Larman and R.R. Phelps for 45 years ago (J. London.…

Functional Analysis · Mathematics 2025-11-03 Shaoqiang Shang

For a Tychonoff space $X$ and a family $\lambda$ of subsets of $X$, we denote by $C_{\lambda}(X)$ the $T_1$-space of all real-valued continuous functions on $X$ with the $\lambda$ -open topology. A topological space is productively…

General Topology · Mathematics 2018-10-11 Alexander V. Osipov

We investigate the Whyburn and weakly Whyburn property in the class of $P$-spaces, that is spaces where every countable intersection of open sets is open. We construct examples of non-weakly Whyburn $P$-spaces of size continuum, thus giving…

General Topology · Mathematics 2010-07-02 Angelo Bella , Camillo Costantini , Santi Spadaro

The weak Whyburn property is a generalization of the classical sequential property that has been studied by many authors. A space $X$ is weakly Whyburn if for every non-closed set $A \subset X$ there is a subset $B \subset A$ such that…

General Topology · Mathematics 2015-11-19 Santi Spadaro

We investigate weak and strong structures for generalized topological spaces, among others products, sums, subspaces, quotients, and the complete lattice of generalized topologies on a given set. Also we introduce $T_{3.5}$ generalized…

General Topology · Mathematics 2016-04-14 E. Makai, , E. Peyghan , B. Samadi

For locally convex spaces, we systematize several known equivalent definitions of Fr\'echet (G\^ ateaux) Differentiability Spaces and Asplund (Weak Asplund) Spaces. As an application, we extend the classical Mazur's theorem as follows: Let…

Functional Analysis · Mathematics 2024-12-16 Jerzy Kakol , Arkady Leiderman
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