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We prove that in a Euclidean space of dimension at least two, there exists a compact set of Lebesgue measure zero such that any real-valued Lipschitz function defined on the space is differentiable at some point in the set. Such a set is…

泛函分析 · 数学 2011-05-17 Michael Doré , Olga Maleva

The main aim of the article is to show, in the absence of the Axiom of Choice, relationships between the following, independent of $\mathbf{ZF}$, statements: "Every countable product of compact metrizable spaces is separable (respectively,…

一般拓扑 · 数学 2021-09-03 Kyriakos Keremedis , Eleftherios Tachtsis , Eliza Wajch

In this paper we study the set of balanced metrics (in Donaldson's terminology) on a compact complex manifold M which are homothetic to a given balanced one. This question is related to various properties of the Tian-Yau-Zelditch…

微分几何 · 数学 2011-05-27 Claudio Arezzo , Andrea Loi , Fabio Zuddas

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

We show that any metacompact Moore space is monotonically metacompact and use that result to characterize monotone metacompactness in certain generalized ordered (GO)spaces. We show, for example, that a generalized ordered space with a…

一般拓扑 · 数学 2011-08-29 Harold R. Bennett , Klaas Pieter Hart , David J. Lutzer

We answer a question of Piotr Minc by proving that there is no compact metrizable space whose set of components contains a unique topological copy of every metrizable compactification of a ray (i.e. a half-open interval) with an arc (i.e.…

一般拓扑 · 数学 2020-01-31 Benjamin Vejnar

Let B(kappa, lambda) be the subalgebra of P(kappa) generated by [kappa]^{<= lambda}. It is shown that if B is any homomorphic image of B(kappa, lambda) then either |B|< 2^lambda or |B|=|B|^lambda, moreover if X is the Stone space of B then…

逻辑 · 数学 2009-09-25 Istvan Juhász , Saharon Shelah

Let $G$ be a compact connected Lie group and $H$ a closed subgroup of $G$. Suppose the homogeneous space $G/H$ is effective and has dimension 3 or higher. Consider a $G$-invariant, symmetric, positive-semidefinite, nonzero (0,2)-tensor…

微分几何 · 数学 2016-06-22 Artem Pulemotov

It is shown that there are infinitely many compact orientable smooth 4-manifolds which do not admit Einstein metrics, but nevertheless satisfy the strict Hitchin-Thorpe inequality 2 chi > 3 |tau|. The examples in question arise as…

dg-ga · 数学 2008-02-03 Claude LeBrun

In this paper we study the properties of P-generated spaces (by analogy with compactly generated). We prove that a regular Lindel\"of generated space with uncountable dispersion character is resolvable. It is proved that Hausdorff…

一般拓扑 · 数学 2017-12-05 Maria A. Filatova , Alexander V. Osipov

We show that any closed biquotient with finite fundamental group admits metrics of positive Ricci curvature. Also, let M be a closed manifold on which a compact Lie group G acts with cohomogeneity one, and let L be a closed subgroup of G…

微分几何 · 数学 2007-05-23 Lorenz Schwachhoefer , Wilderich Tuschmann

In this paper we consider the moduli space of complete, conformally flat metrics on a sphere with k punctures having constant positive Q-curvature and positive scalar curvature. Previous work has shown that such metrics admit an asymptotic…

微分几何 · 数学 2025-03-13 João Henrique Andrade , João Marcos do Ó , Jesse Ratzkin

We prove that $n$-dimensional ($n\geqslant3$) complete and non-compact metric measure spaces with non-negative weighted Ricci curvature in which some Caffarelli-Kohn-Nirenberg type inequality holds are close to the model metric measure…

微分几何 · 数学 2014-10-03 Jing Mao

We construct a homogeneous subspace of $2^\omega$ whose complement is dense in $2^\omega$ and rigid. Using the same method, assuming Martin's Axiom, we also construct a countable dense homogeneous subspace of $2^\omega$ whose complement is…

一般拓扑 · 数学 2014-10-03 Andrea Medini , Jan van Mill , Lyubomyr Zdomskyy

The Lichnerowicz conjecture asserts that all harmonic manifolds are either flat or locally symmetric spaces of rank 1. This conjecture has been proved by Z.I. Szabo for harmonic manifolds with compact universal cover. E. Damek and F. Ricci…

微分几何 · 数学 2013-02-18 Gerhard Knieper , Norbert Peyerimhoff

We construct a compact Hausdorff space $K$ such that the space $P(K)$ of Radon probabiblity measures on $K$ considered with the weak$^*$ topology (induced from the space of continuous functions $C(K)$) is countably tight which is a…

泛函分析 · 数学 2023-12-06 Piotr Koszmider , Zdeněk Silber

We show that if a compact complex manifold admits a K\"ahler metric whose holomorphic sectional curvature is everywhere non positive and strictly negative in at least one point, then its canonical bundle is positive.

微分几何 · 数学 2018-07-19 Simone Diverio , Stefano Trapani

We prove an extension of the Moore-Schmidt theorem on the triviality of the first cohomology class of cocycles for the action of an arbitrary discrete group on an arbitrary measure space and for cocycles with values in an arbitrary compact…

动力系统 · 数学 2022-02-10 Asgar Jamneshan , Terence Tao

We consider the cardinal sequences of compact scattered spaces in models where CH is false. We describe a number of models where the continuum is aleph_2 in which no such space can have aleph_2 countable levels.

一般拓扑 · 数学 2007-05-23 Kenneth Kunen

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…

一般拓扑 · 数学 2025-07-29 Anton Lipin