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We discuss definable compactifications and topological dynamics. For G a group definable in some structure M, we define notions of "definable" compactification of G and "definable" action of G on a compact space X (definable G-flow), where…

Logic · Mathematics 2012-12-14 Jakub Gismatullin , Davide Penazzi , Anand Pillay

Sormani and Wei proved in 2004 that a compact geodesic space has a categorical universal cover if and only if its covering/critical spectrum is finite. We add to this several equivalent conditions pertaining to the geometry and topology of…

General Topology · Mathematics 2013-09-16 Jay Wilkins

We define the compact universal cover of a compact, metrizable connected space (i.e. a continuum) X to be the inverse limit of all continua that regularly cover X. We show that such covers do indeed form an inverse system with bonding maps…

Algebraic Topology · Mathematics 2022-09-07 Conrad Plaut

The construction of manifold structures and fundamental classes on the (compactified) moduli spaces appearing in Gromov-Witten theory is a long-standing problem. Up until recently, most successful approaches involved the imposition of…

Symplectic Geometry · Mathematics 2014-05-27 Andreas Gerstenberger

There are several compactification procedures in topology, but there is only one standard discretization, namely, replacing the original topology with the discrete topology. We give a notion of discretization which is dual (in categorical…

General Topology · Mathematics 2014-12-16 Massoud Amini , Nasser Golestani

Theorem (uniformization). Let X be a compact Kahler manifold of dimension n with large, residually finite and nonamenable fundamental group. Then its universal covering is a bounded domain in the n-dimensional affine space.

Algebraic Geometry · Mathematics 2016-08-01 Robert Treger

A topology on a nonempty set $X$ specifies a natural subset of $\mathcal{P}(X)$. By identifying $\mathcal{P}(\mathcal{P}(X))$ with the totally disconnected compact Hausdorff space $2^{\mathcal{P}(X)}$, the lattice $Top(X)$ of all topologies…

General Topology · Mathematics 2011-12-09 Jorge L. Bruno , Aisling E. McCluskey

A coarse compactification of a proper metric space $X$ is any compactification of $X$ that is dominated by its Higson compactification. In this paper we describe the maximal coarse compactification of $X$ whose corona is of dimension $0$.…

Metric Geometry · Mathematics 2021-02-10 Yuankui Ma , Jerzy Dydak

We define a notion of relative fundamental class that applies to moduli spaces in gauge theory and in symplectic Gromov-Witten theory. For universal moduli spaces over a parameter space, the relative fundamental class specifies an element…

Symplectic Geometry · Mathematics 2018-04-27 Eleny-Nicoleta Ionel , Thomas H. Parker

In the present paper, we examine in detail the method of "graph compactifications" of topological groups. The graph and Ellis methods of constructing proper compactifications of topological groups are applied for the investigation of…

General Topology · Mathematics 2026-04-28 K. L. Kozlov , A. G. Leiderman

There exist two known canonical types of ultrafilter extensions of first-order models; one comes from modal logic and universal algebra, another one from model theory and algebra of ultrafilters, with ultrafilter extensions of semigroups as…

Logic · Mathematics 2021-06-17 Nikolai L. Poliakov , Denis I. Saveliev

The class of subsets of locally convex spaces called $\mu$-compact sets is considered. This class contains all compact sets as well as several noncompact sets widely used in applications. It is shown that many results well known for compact…

Functional Analysis · Mathematics 2015-05-18 V. Yu. Protasov , M. E. Shirokov

Let X be a Zariski open subset of a compact Kaehler manifold. In this paper, we study the set $\Sigma^k(X)$ of one dimensional local systems on X with nonvanishing kth cohomology. We show that under certain conditions (X compact, X has a…

alg-geom · Mathematics 2008-02-03 Donu Arapura

We prove a correspondence between $\kappa$-small fibrations in simplicial presheaf categories equipped with the injective or projective model structure (and left Bousfield localizations thereof) and relatively $\kappa$-compact maps in their…

Category Theory · Mathematics 2023-01-25 Raffael Stenzel

In this note a notion of generalized topological entropy for arbitrary subsets of the space of all sequences in a compact topological space is introduced. It is shown that for a continuous map on a compact space the generalized topological…

Dynamical Systems · Mathematics 2024-10-29 Maysam Maysami Sadr , Mina Shahrestani

In this paper, we are interested in study subgroups of topologized fundamental groups and their influences on generalized covering maps. More precisely, we find some relationships between generalized covering subgroups and the other famous…

Algebraic Topology · Mathematics 2016-02-26 Mehdi Abdullahi Rashid , Behrooz Mashayekhy , Hamid Torabi , Seyyed Zeynal Pashaei

The classical theory of regularity of embeddings of compact convex sets was developed in the 1970s, exclusively in the real case, and even there it does not appear to have been stated in its simplest form. We begin by revisiting this…

Operator Algebras · Mathematics 2026-02-04 David P. Blecher

Let $G$ be a locally compact group. For every $G$-flow $X$, one can consider the stabilizer map $x \mapsto G_x$, from $X$ to the space $\mathrm{Sub}(G)$ of closed subgroups of $G$. This map is not continuous in general. We prove that if one…

Group Theory · Mathematics 2023-11-07 Adrien Le Boudec , Todor Tsankov

We develop a generalized covering space theory for a class of uniform spaces called coverable spaces. Coverable spaces include all geodesic metric spaces, connected and locally pathwise connected compact topological spaces, in particular…

Algebraic Topology · Mathematics 2007-05-23 Valera Berestovskii , Conrad Plaut

In analogy with the classical theory of filters, for fi\-nite\-ly complete or small cat\-e\-go\-ries, we provide the concepts of fil\-ter, $\mathfrak{G}$-neigh\-bor\-hood (short for "Grothendieck-neigh\-bor\-hood") and…

Category Theory · Mathematics 2021-12-02 Joaquín Luna-Torres