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This note provides a correct proof of the result claimed by the second author that locally compact normal spaces are collectionwise Hausdorff in certain models obtained by forcing with a coherent Souslin tree. A novel feature of the proof…

一般拓扑 · 数学 2019-08-15 Alan Dow , Franklin D. Tall

We show that if a topological or paratopological group $G$ contains a stationary subset of some regular uncountable cardinal, then $G$ contains a subspace which is not collectionwise normal. This statement implies that if a monotonically…

一般拓扑 · 数学 2012-09-24 Raushan Buzyakova , Cetin Vural

A topological space $X$ is called hereditarily supercompact if each closed subspace of X is supercompact. By a combined result of Bula, Nikiel, Tuncali, Tymchatyn, and Rudin, each monotonically normal compact Hausdorff space is hereditarily…

一般拓扑 · 数学 2014-12-04 Taras Banakh , Zdzislaw Kosztolowicz , Slawomir Turek

We show a number of undecidable assertions concerning countably compact spaces hold under PFA(S)[S]. We also show the consistency without large cardinals of "every locally compact, perfectly normal space is paracompact".

逻辑 · 数学 2016-07-18 Alan Dow , Franklin D. Tall

An $\omega_1$-compact space is a space in which every closed discrete subspace is countable. We give various general conditions under which a locally compact, $\omega_1$-compact space is $\sigma$-countably compact, i.e., the union of…

一般拓扑 · 数学 2022-06-07 Peter Nyikos , Lyubomyr Zdomskyy

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…

一般拓扑 · 数学 2011-04-19 Franklin D. Tall

In this paper we investigate hereditarily normal topological groups and their subspaces. We prove that every compact subspace of a hereditarily normal topological group is metrizable. To prove this statement we first show that a…

一般拓扑 · 数学 2012-09-11 Raushan Buzyakova

Orderability, weak orderability and the existence of continuous weak selections on filter spaces (i.e., spaces with a single non-isolated point) and their products are discussed. We prove that a closed continuous image X of a suborderable…

一般拓扑 · 数学 2017-10-19 Koichi Motooka , Dmitri Shakhmatov , Takamitsu Yamauchi

We prove that, under suitable assumptions on a category C, the existence of supercompact cardinals implies that every absolute epireflective class of objects of C is a small-orthogonality class. More precisely, if L is a localization…

范畴论 · 数学 2007-05-23 Joan Bagaria , Carles Casacuberta , Adrian R. D. Mathias

P.J. Nyikos has asked whether it is consistent that every hereditarily normal manifold of dimension > 1 is metrizable, and proved it is if one assumes the consistency of a supercompact cardinal, and, in addition, that the manifold is…

一般拓扑 · 数学 2016-07-19 Alan Dow , Franklin D. Tall

A space $X$ is submaximal if any dense subset of $X$ is open. In this paper, we prove that every submaximal topological gyrogroup of non-measurable cardinality is strongly $\sigma$-discrete. Moreover, we prove that every submaximal strongly…

一般拓扑 · 数学 2020-11-11 Meng Bao , Fucai Lin

This paper explores several topics related to Woodin's HOD conjecture. We improve the large cardinal hypothesis of Woodin's HOD dichotomy theorem from an extendible cardinal to a strongly compact cardinal. We show that assuming there is a…

逻辑 · 数学 2021-07-02 Gabriel Goldberg

We show relative to strong hypotheses that patterns of compact cardinals in the universe, where a compact cardinal is one which is either strongly compact or supercompact, can be virtually arbitrary. Specifically, we prove if V is a model…

逻辑 · 数学 2007-05-23 Arthur W. Apter

Let omega be the first infinite ordinal (or the set of all natural numbers) with the usual order <. In section 1 we show that, assuming the consistency of a supercompact cardinal, there may exist an ultrapower of omega, whose cardinality is…

逻辑 · 数学 2009-09-25 Renling Jin , Saharon Shelah

A continuum $K$ is a common model for the family ${\mathcal K}$ of continua if every member of ${\mathcal K}$ is a continuous image of $K$. We show that none of the following classes of spaces has a common model: 1) the class of strongly…

一般拓扑 · 数学 2017-04-25 Jerzy Krzempek , Elżbieta Pol

We prove that each metrizable space (of cardinality less or equal to continuum) has a (first countable) uniform Eberlein compactification and each scattered metrizable space has a scattered hereditarily paracompact compactification. Each…

一般拓扑 · 数学 2012-12-19 Taras Banakh , Arkady Leiderman

The aim of this paper is to continue the study of sg-compact spaces. The class of sg-compact spaces is a proper subclass of the class of hereditarily compact spaces. In our paper we shall consider sg-compactness in product spaces. Our main…

一般拓扑 · 数学 2007-05-23 Julian Dontchev , Maximilian Ganster

We introduce the concept of hereditarily non uniformly perfect sets, compact sets for which no compact subset is uniformly perfect, and compare them with the following: Hausdorff dimension zero sets, logarithmic capacity zero sets, Lebesgue…

复变函数 · 数学 2017-01-24 Rich Stankewitz , Toshiyuki Sugawa , Hiroki Sumi

We introduce the notion of hereditary G-compactness (with respect to interpretation). We provide a sufficient condition for a poset to not be hereditarily G-compact, which we use to show that any linear order is not hereditarily G-compact.…

逻辑 · 数学 2022-03-11 Tomasz Rzepecki

A topological space $G$ is said to be a {\it rectifiable space} provided that there are a surjective homeomorphism $\varphi :G\times G\rightarrow G\times G$ and an element $e\in G$ such that $\pi_{1}\circ \varphi =\pi_{1}$ and for every…

一般拓扑 · 数学 2015-07-17 Fucai Lin , Jing Zhang , Kexiu Zhang
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