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In this paper, we introduce the notions of pre-uniform spaces and pre-proximities and investigate some basic properties about them, where the definition of pre-uniformity here is different with the pre-uniformities which are studied in…

General Topology · Mathematics 2022-11-29 Fucai Lin , Yufan Xie , Ting Wu , Meng Bao

Groups of almost upper triangular infinite matrices with entries indexed by integers are studied. It is shown that, when the matrices are over a finite field, these groups admit a nondiscrete totally disconnected, locally compact group…

Group Theory · Mathematics 2019-12-17 Peter Groenhout , Colin D. Reid , George A. Willis

For a regular space $X$, the hyperspace $(CL(X), \tau_{F})$ (resp., $(CL(X), \tau_{V})$) is the space of all nonempty closed subsets of $X$ with the Fell topology (resp., Vietoris topology). In this paper, we give the characterization of…

General Topology · Mathematics 2022-11-11 Chuan Liu , Fucai Lin

A self-similar group of finite type is the profinite group of all automorphisms of a regular rooted tree that locally around every vertex act as elements of a given finite group of allowed actions. We provide criteria for determining when a…

Group Theory · Mathematics 2014-09-02 Ievgen V. Bondarenko , Igor O. Samoilovych

We construct a finitely presented group with infinitely many non-homeomorphic asymptotic cones. We also show that the existence of cut points in asymptotic cones of finitely presented groups does, in general, depend on the choice of scaling…

Group Theory · Mathematics 2011-08-26 Denis Osin , Abderezak Ould Houcine

We exhibit a pseudogroup of smooth local transformations of the real line which is compactly generated, but not realizable as the holonomy pseudogroup of a foliation of codimension 1 on a compact manifold. The proof relies on a description…

Geometric Topology · Mathematics 2021-01-06 Gael Meigniez

We define a metric ultraproduct of topological groups with left-invariant metric, and show that there is a countable sequence of finite groups with left-invariant metric whose metric ultraproduct contains isometrically as a subgroup every…

Group Theory · Mathematics 2017-06-15 Michal Doucha

A group topology is said to be linear if open subgroups form a base of neighborhoods of the identity element. It is proved that the existence of a nondiscrete extremally disconnected group of Ulam nonmeasurable cardinality with linear…

General Topology · Mathematics 2021-04-27 Ol'ga Sipacheva

Working in the soft-element (classical) viewpoint, we introduce \emph{soft bitopological groups}: soft groups endowed with two soft topologies such that the induced topologies on the set of soft elements make the soft-element group into a…

General Topology · Mathematics 2026-02-16 S. Ray

We will explore the nature of when certain finite groups have an equal covering, and when finite groups do not. Not to be confused with the concept of a cover group, a covering of a group is a collection of proper subgroups whose…

Group Theory · Mathematics 2022-07-01 Andrew Velasquez-Berroteran

We study the existence of uncountable first-order structures that are homogeneous with respect to their finitely generated substructures. In many classical cases this is either well-known or follows from general facts, for example, if the…

Logic · Mathematics 2025-10-21 Adam Bartoš , Wiesław Kubiś

(1) Every infinite, Abelian compact (Hausdorff) group K admits 2^|K|-many dense, non-Haar-measurable subgroups of cardinality |K|. When K is nonmetrizable, these may be chosen to be pseudocompact. (2) Every infinite Abelian group G admits a…

General Topology · Mathematics 2013-10-09 W. W. Comfort , S. U. Raczkowski , F. J. Trigos-Arrieta

In the framework of the generalized measure theory the decomposable probabilistic-valued set functions are introduced with triangle functions $\tau$ in an appropriate probabilistic metric space as natural candidates for the "addition",…

Probability · Mathematics 2014-11-20 Lenka Halčinová , Ondrej Hutník , Jana Molnárová

Topological groups whose underlying spaces are basically disconnected, $F$-, or $F'$-spaces but not $P$-spaces are considered. It is proved, in particular, that the existence of a Lindel\"of basically disconnected topological group which is…

General Topology · Mathematics 2022-08-18 Ol'ga Sipacheva

As defined in [1], a Hausdorff space is strongly anti-Urysohn (in short: SAU) if it has at least two non-isolated points and any two infinite} closed subsets of it intersect. Our main result answers the two main questions of [1] by…

General Topology · Mathematics 2021-06-02 István Juhász , Saharon Shelah , LAjos Soukup , Zoltán Szentmiklóssy

We show, assuming PD, that every complete finitely axiomatized second order theory with a countable model is categorical, but that there is, assuming again PD, a complete recursively axiomatized second order theory with a countable model…

Logic · Mathematics 2024-05-07 Tapio Saarinen , Jouko Väänänen , William Hugh Woodin

We continue our study of ends non-compact manifolds. The over-arching aim is to provide an appropriate generalization of Siebenmann's famous collaring theorem that applies to manifolds having non-stable fundamental group systems at…

Geometric Topology · Mathematics 2009-03-03 Craig R Guilbault , Frederick C Tinsley

It has been recently observed that fundamental aspects of the classical theory of factorization can be greatly generalized by combining the languages of monoids and preorders. This has led to various theorems on the existence of certain…

Rings and Algebras · Mathematics 2023-09-18 Laura Cossu , Salvatore Tringali

We prove that the existence of a selective ultrafilter implies the existence of a countably compact Hausdorff group topology on the free Abelian group of size continuum. As a consequence, we show that the existence of a selective…

General Topology · Mathematics 2020-06-25 A. C. Boero , I. Castro-Pereira , A. H. Tomita

We study two variations of Bowen's definitions of topological entropy based on separated and spanning sets which can be applied to the study of discontinuous semiflows on compact metric spaces. We prove that these definitions reduce to…

Dynamical Systems · Mathematics 2018-05-14 Nelda Jaque , Bernardo San Martín
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