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We show (in ZFC) that the cardinality of a compact homogeneous space of countable tightness is no more than the size of the continuum.

一般拓扑 · 数学 2007-05-23 Ramiro de la Vega

We discuss homogeneity and universality issues in the theory of abstract linear spaces, namely, structures with points and lines satisfying natural axioms, as in Euclidean or projective geometry. We show that the two smallest projective…

逻辑 · 数学 2022-05-27 Wiesław Kubiś , Piotr Nowakowski , Tomasz Rzepecki

It is shown that CH implies the existence of a compact Hausdorff space that is countable dense homogeneous, crowded and does not contain topological copies of the Cantor set. This contrasts with a previous result by the author which says…

一般拓扑 · 数学 2020-01-20 Rodrigo Hernández-Gutiérrez

We will show that, consistently, every uncountable set can be continuously mapped onto a non measure zero set, while there exists an uncountable set whose all continuous images into a Polish space are meager.

逻辑 · 数学 2007-05-23 Tomek Bartoszynski , Saharon Shelah

We show that all sufficiently nice $\lambda$-sets are countable dense homogeneous ($\mathsf{CDH}$). From this fact we conclude that for every uncountable cardinal $\kappa \le \mathfrak{b}$ there is a countable dense homogeneous metric space…

一般拓扑 · 数学 2018-09-19 Rodrigo Hernández-Gutiérrez , Michael Hrušák , Jan van Mill

The main result of this article is: THEOREM. Every homogeneous locally conical connected separable metric space that is not a $1$-manifold is strongly $n$-homogeneous for each $n \geq 2$ and countable dense homogeneous. Furthermore,…

一般拓扑 · 数学 2017-06-02 Fredric D. Ancel , David P. Bellamy

Extending a result of R. de la Vega, we prove that an infinite homogeneous compactum has cardinality $\mathfrak{c}$ if either it is the union of countably many dense or finitely many arbitrary countably tight subspaces. The question if…

一般拓扑 · 数学 2016-07-05 István Juhász , Jan van Mill

Adapting a homotopy reconstruction theorem for general metric compacta, we show that every countable metric or ultrametric compact space can be topologically reconstructed as the inverse limit of a sequence of finite $T_0$ spaces which are…

一般拓扑 · 数学 2024-12-20 Diego Mondéjar

We provide examples of nonseparable compact spaces with the property that any continuous image which is homeomorphic to a finite product of spaces has a maximal prescribed number of nonseparable factors.

一般拓扑 · 数学 2014-09-15 Antonio Avilés

Recall that the Rado graph is the unique countable graph that realizes all one-point extensions of its finite subgraphs. The Rado graph is well-known to be universal and homogeneous in the sense that every isomorphism between finite…

逻辑 · 数学 2018-07-17 Jan Grebík

It is proved that no region of a homogeneous locally compact, locally connected metric space can be cut by an $F_\sigma$-subset of a "smaller" dimension. The result applies to different finite or infinite topological dimensions of…

一般拓扑 · 数学 2009-01-13 P. Krupski , V. Valov

Homogeneous countably compact spaces $X$ and $Y$ whose product $X\times Y$ is not pseudocompact are constructed. It is proved that all compact subsets of homogeneous subspaces of the third power of an extremally disconnected space are…

一般拓扑 · 数学 2023-06-13 Evgenii Reznichenko

Improving on an earlier example by J. van Mill, we prove that there exists a zero-dimensional compact space of countable pi-weight and uncountable character which is homogeneous under MA+notCH, but not under CH.

一般拓扑 · 数学 2007-05-23 K. P. Hart , G. J. Ridderbos

We classify the metric spaces that can be approximated by finite homogeneous ones.

群论 · 数学 2013-03-21 Tsachik Gelander

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…

一般拓扑 · 数学 2022-05-25 Eman Almuhur , Muhammad Ahsan Khan

This is a survey of the recent results and unsolved problems about locally compact homogeneous metric spaces. Mostly, homogeneous finite-dimensional $ANR$-spaces are discussed.

一般拓扑 · 数学 2024-01-02 Vesko Valov

All spaces are assumed to be separable and metrizable. We show that, assuming the Axiom of Determinacy, every zero-dimensional homogeneous space is strongly homogeneous (that is, all its non-empty clopen subspaces are homeomorphic), with…

一般拓扑 · 数学 2020-03-03 Raphaël Carroy , Andrea Medini , Sandra Müller

A topological space is nonseparably connected if it is connected but all of its connected separable subspaces are singletons. We show that each connected first countable space is the image of a nonseparably connected complete metric space…

度量几何 · 数学 2009-11-05 T. Banakh , M. Vovk , M. R. Wójcik

We show that $X^\lambda$ is strongly homogeneous whenever $X$ is a non-separable zero-dimensional metrizable space and $\lambda$ is an infinite cardinal. This partially answers a question of Terada, and improves a previous result of the…

一般拓扑 · 数学 2025-08-19 Andrea Medini

We count the number of countable homogeneous colored linear orderings in $k$ colors. Relatedly, we count the number of countable $C_{n,m}$-homogeneous linear orderings. $C_{n,m}$-homogeneity is a strong homogeneity notion that approximates…

组合数学 · 数学 2026-04-17 David Gonzalez
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