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It is proved that for an h-homogeneous space X the following conditions are equivalent: 1) X is a densely homogeneous space with a dense complete subspace; 2) X is $\sigma$-discretely controlled.

一般拓扑 · 数学 2016-01-18 Sergey Medvedev

Given compact Lie groups H\subset G, we study the space of G-invariant metrics on G/H with nonnegative sectional curvature. For an intermediate subgroup K between H and G, we derive conditions under which enlarging the Lie algebra of K…

微分几何 · 数学 2008-06-24 Lorenz Schwachhofer , Kristopher Tapp

We prove that if $\mathcal{F}$ is a non-meager $P$-filter, then both $\mathcal{F}$ and ${}^\omega\mathcal{F}$ are countable dense homogeneous spaces.

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

We show that if a separable space X has a meager open subset containing a copy of the Cantor set 2^\omega, then X has $\frak{c}$ types of countable dense subsets. We suggest a generalization of the \lambda-set for non-separable spaces. Let…

一般拓扑 · 数学 2014-02-04 Sergey Medvedev

A space has $\sigma$-compact tightness if the closures of $\sigma$-compact subsets determines the topology. We consider a dense set variant that we call densely k-separable. We consider the question of whether every densely k-separable…

一般拓扑 · 数学 2018-10-12 Alan Dow , Istvan Juhasz

The extended weight semigroup of a homogeneous space G/H of a connected semisimple algebraic group G characterizes the spectra of the representations of G on the spaces of regular sections of homogeneous linear bundles over G/H, including…

表示论 · 数学 2011-11-15 Roman Avdeev

All spaces are assumed to be separable and metrizable. Building on work of van Engelen, Harrington, Michalewski and Ostrovsky, we obtain the following results: (1) Every finite-dimensional analytic space is $\sigma$-homogeneous with…

一般拓扑 · 数学 2024-03-22 Claudio Agostini , Andrea Medini

We prove that every homogeneous countable dense homogeneous topological space containing a copy of the Cantor set is a Baire space. In particular, every countable dense homogeneous topological vector space is a Baire space. It follows that,…

一般拓扑 · 数学 2023-09-28 Tadeusz Dobrowolski , Mikołaj Krupski , Witold Marciszewski

All spaces are assumed to be separable and metrizable. Ostrovsky showed that every zero-dimensional Borel space is $\sigma$-homogeneous. Inspired by this theorem, we obtain the following results: assuming $\mathsf{AD}$, every…

一般拓扑 · 数学 2023-07-18 Andrea Medini , Zoltán Vidnyánszky

We give an affirmative answer to the following question: Is any Borel subset of a Cantor set $\textbf{ C}$ a sum of a countable number of pairwise disjoint $h$-homogeneous subspaces that are closed in $X$? It follows that every Borel set $X…

逻辑 · 数学 2011-02-17 Alexey Ostrovsky

We prove that if an analytic subset $A$ of a linear metric space $X$ is not contained in a $\sigma Z_\omega$-subset of $X$ then for every Polish convex set $K$ with dense affine hull in $X$ the sum $A+K$ is non-meager in $X$ and the sets…

一般拓扑 · 数学 2021-11-01 Taras Banakh

Let G be a semisimple linear algebraic group defined over rational numbers, K be a maximal compact subgroup of its real points and {\Gamma} be an arithmetic lattice. One can associate a probability measure {\mu}(H) on {\Gamma}\G for each…

动力系统 · 数学 2021-01-15 Runlin Zhang

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

It is shown that quantum homogeneous spaces of a quantum group H can be viewed as fibres of quantum fibrations with the total space H that are dual to coalgebra bundles. As concrete examples of such structures the fibrations with the…

q-alg · 数学 2009-10-30 Tomasz Brzezinski

Let G be a simple non-compact linear connected Lie group and H be a closed non-compact semisimple subgroup. We are interested in finding classes of homogeneous spaces G/H admitting proper actions of discrete non virtually abelian subgroups…

群论 · 数学 2022-04-11 Maciej Bochenski , Piotr Jastrzebski , Aleksy Tralle

The purpose of this paper is to introduce and investigate some basic properties of mixed homogeneous Herz-Hardy spaces $H\dot{K}_{\vec{p}}^{\alpha, q}(\mathbb{R}^n)$ and mixed non-homogeneous Herz-Hardy spaces $HK_{\vec{p}}^{\alpha,…

泛函分析 · 数学 2022-05-24 Yichun Zhao , Mingquan Wei , Jiang Zhou

We detect Hilbert manifolds among isometrically homogeneous metric spaces and apply the obtained results to recognizing Hilbert manifolds among homogeneous spaces of the form G/H where G is a metrizable topological group and H is a closed…

几何拓扑 · 数学 2011-08-23 Taras Banakh , Dusan Repovs

In the present article we study the following problem. Let G be a linear algebraic group over Q, $\Gamma$ be an arithmetic lattice and H be an observable Q-subgroup. There is a H-invariant measure $\mu_H$ supported on the closed submanifold…

动力系统 · 数学 2020-03-04 Runlin Zhang

We investigate which definable separable metric spaces are countable dense homogeneous (CDH). We prove that a Borel CDH space is completely metrizable and give a complete list of zero-dimensional Borel CDH spaces. We also show that for a…

一般拓扑 · 数学 2013-10-09 Michael Hrusak , Beatriz Zamora Aviles

We introduce the classes of (strongly) ($\Theta$-)discrete homogeneous spaces. We discuss the relationships of these classes to other classes of spaces possessing homogeneity-related properties, such as (strongly) ($n$-)homogeneous spaces.…

几何拓扑 · 数学 2022-11-15 Vitaly Chatyrko , Alexandre Karassev
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