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In this paper, by introducing some kind of small loop transfer spaces at a point, we study the behavior of topologized fundamental groups with the compact-open topology and the whisker topology, $\pi_{1}^{qtop}(X,x_{0})$ and…

A topological group $X$ is called $duoseparable$ if there exists a countable set $S\subseteq X$ such that $SUS=X$ for any neighborhood $U\subseteq X$ of the unit. We construct a functor $F$ assigning to each (abelian) topological group $X$…

General Topology · Mathematics 2021-11-01 Taras Banakh , Igor Guran , Alex Ravsky

Every countable topological group $G$ has a closed discrete subset $A$ such that $G=AA^{-1}.$

General Topology · Mathematics 2015-11-04 Igor Protasov

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

A discrete subset $S$ of a topologically gyrogroup $G$ is called a {\it suitable set} for $G$ if $S\cup \{1\}$ is closed and the subgyrogroup generated by $S$ is dense in $G$, where $1$ is the identity element of $G$. In this paper, we…

General Topology · Mathematics 2025-08-19 Jiamin He , Jiajia Yang , Fucai Lin

We work in set-theory without choice ZF. Denoting by AC(N) the countable axiom of choice, we show in ZF+AC(N) that the closed unit ball of a uniformly convex Banach space is compact in the convex topology (an alternative to the weak…

Functional Analysis · Mathematics 2008-12-18 Marianne Morillon

In this paper we establish a connection between categorical closedness and topologizability of semigroups. In particular, for a class $\mathsf T_{\!1}\mathsf S$ of $T_1$ topological semigroups we prove that a countable semigroup $X$ with…

General Topology · Mathematics 2022-12-27 Taras Banakh , Serhii Bardyla

A discrete subset $S$ of a topological group $G$ is called a {\it suitable set} for $G$ if $S\cup \{e\}$ is closed in $G$ and the subgroup generated by $S$ is dense in $G$, where $e$ is the identity element of $G$. In this paper, the…

General Topology · Mathematics 2026-04-23 Fucai Lin , Jiamin He , Jiajia Yang , Chuan Liu

A topological group $X$ is called connected if the only subsets which are both open and closed are the whole space $X$ and the null set $\emptyset$. A subset of a topological group is connected if the subspace is connected. We say that a…

General Topology · Mathematics 2012-01-24 Huseyin Cakalli

In this paper we focus on the set-open topologies on the group $\mathcal{H}(X)$ of all self-homeomorphisms of a topological space $X$ which yield continuity of both the group operations, product and inverse function. As a consequence, we…

General Topology · Mathematics 2020-02-20 Alexander V. Osipov

In this paper we introduce and study three new cardinal topological invariants called the cs*, cs-, and sb-characters. The class of topological spaces with countable cs*-character is closed under many topological operations and contains all…

General Topology · Mathematics 2011-08-23 Taras Banakh , Lyubomyr Zdomskyy

A subset $B \subset Y$ is constructible if it is an element of the smallest family that contains all open sets and is stable under finite intersections and complements. A function $f : X \to Y$ is said to be piece-wise closed if $X$ can be…

General Topology · Mathematics 2012-05-29 Alexey Ostrovsky

Internal preneighbourhood spaces inside any finitely complete category with finite coproducts and proper factorisation structure were first introduced in my earlier paper. This paper proposes a closure operation on internal preneighbourhood…

Category Theory · Mathematics 2022-05-12 Partha Pratim Ghosh

In this paper, we define the notion of closed models defined by counting, and we compute their homotopy categories. We apply this construction to various categories of graphs. We show that there does not exist a closed model in the category…

Category Theory · Mathematics 2017-04-04 Tsemo Aristide

In this paper we give sufficient conditions under which a subsemigroup of a topological group is a subgroup, adding to the results given in \cite{Kosh, can, axioms, forum, Hof, cc, locally} where conditions exist (such as locally…

General Topology · Mathematics 2020-12-23 Julio César Hernández Arzusa

We introduce the Insertion Chain Complex, a higher-dimensional extension of insertion graphs, as a new framework for analyzing finite sets of words. We study its topological and combinatorial properties, in particular its homology groups,…

Combinatorics · Mathematics 2025-09-17 Nataša Jonoska , Francisco Martinez-Figueroa , Masahico Saito

The concept of $typed$ $topology$ is introduced. In a typed topological space, some open sets are assigned "types", and topological concepts such as closure, connectedness can be defined using types. A finite data set in $R^2$ is a…

General Topology · Mathematics 2024-02-13 Wanjun Hu

In this note for a topological group $G$, we introduce a bounded subset of $G$ and we find some relationships of this definition with other topological properties of $G$.

Group Theory · Mathematics 2010-03-16 Kazem Haghnejad Azar

In this article, we introduce an interesting topology-like concept concerning groups (and with almost the same method it can be defined for other algebraic systems). Given an arbitrary group $G$, we define a {\em topo-system} on $G$ as a…

Group Theory · Mathematics 2014-12-09 M. Shahryari

We consider interpretable topological spaces and topological groups in a $p$-adically closed field $K$. We identify a special class of "admissible topologies" with topological tameness properties like generic continuity, similar to the…

Logic · Mathematics 2022-08-23 Will Johnson