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There is a locally compact Hausdorff space of weight aleph_omega which is linearly Lindelof and not Lindelof. This improves an earlier result, which produced such a space of weight beth_omega.

General Topology · Mathematics 2007-05-23 Kenneth Kunen

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

We consider special subclasses of the class of Lindel\"of Sigma-spaces obtained by imposing restrictions on the weight of the elements of compact covers that admit countable networks: A space $X$ is in the class $L\Sigma(\leq\kappa)$ if it…

General Topology · Mathematics 2012-10-23 Wieslaw Kubis , Oleg Okunev , Paul J. Szeptycki

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 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

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

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 investigate the mapping class groups of a class of non-Hausdorff topological spaces which includes finite spaces. We show that the mapping class group of a finite space is isomorphic to the homeomorphism group of its $T_0$ quotient. As a…

General Topology · Mathematics 2020-11-05 B. Branman

We give a complete classification of mixed Tsirelson spaces T[(F\_i, theta\_i)\_{i=1}^r ] for finitely many pairs of given compact and hereditary families F\_i of finite sets of integers and 0<theta\_i<1 in terms of the Cantor-Bendixson…

Functional Analysis · Mathematics 2007-05-23 Jordi Lopez Abad , Antonis Manoussakis

We define a notion of (one-sided) shift spaces over infinite alphabets. Unlike many previous approaches to shift spaces over countable alphabets, our shift spaces are compact Hausdorff spaces. We examine shift morphisms between these shift…

Operator Algebras · Mathematics 2013-07-03 William Ott , Mark Tomforde , Paulette Willis

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

We examine locally compact normal spaces in models of form PFA(S)[S], in particular characterizing paracompact, countably tight ones as those which include no perfect pre-image of omega_1 and in which all separable closed subspaces are…

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

In this paper, some features of countably $\alpha$-compact topological spaces are presented and proven. The connection between countably $\alpha$% -compact, Tychonoff, and $\alpha$-Hausdorff spaces is explained. The space is countably…

General Topology · Mathematics 2022-05-25 Eman Almuhur , Muhammad Ahsan Khan

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 obtain several results and examples concerning the general question ``When must a space with a small diagonal have a G_delta-diagonal?". In particular, we show (1) every compact metrizably fibered space with a small diagonal is…

General Topology · Mathematics 2007-05-23 Gary Gruenhage

We investigate connections between resolvability and different forms of tightness. This study is adjacent to [1,2]. We construct a non-regular refinement $\tau^*$ of the natural topology of the real line $\mathbb{R}$ with properties such…

General Topology · Mathematics 2025-07-29 Anton Lipin

We show that the subsemigroup of the product of w_1-many circles generated by the L-space constructed by J. Moore is again an L-space. This leads to a new example of a Lindelof topological group. The question whether all finite powers of…

General Topology · Mathematics 2010-02-25 Dusan Repovs , Lyubomyr Zdomskyy

The aim of this paper is introduce and initiate the study of extremally $T_1$-spaces, i.e., the spaces where all hereditarily compact $C_2$-subspaces are closed. A $C_2$-space is a space whose nowhere dense sets are finite.

General Topology · Mathematics 2007-05-23 Julian Dontchev , Maximilian Ganster , Laszlo Zsilinszky

A cardinal lambda is called omega-inaccessible if for all mu < lambda we have mu^omega<lambda. We show that for every omega-inaccessible cardinal lambda there is a CCC (hence cardinality and cofinality preserving) forcing that adds a…

Logic · Mathematics 2007-05-23 Istvan Juhasz , Saharon Shelah

We show that a Tychonoff discretely star-Lindelof space can have arbitrarily big extent and note that there are consistent examples of normal discretely star-Lindelof spaces with uncountable extent.

General Topology · Mathematics 2007-05-23 Mikhail Matveev
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