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The property of countable metacompactness of a topological space gets its importance from Dowker's 1951 theorem that the product of a normal space X with the unit interval is again normal iff X is countably metacompact. In a recent paper,…

Logic · Mathematics 2024-05-29 Rodrigo Carvalho , Tanmay Inamdar , Assaf Rinot

The aim of this paper is to give natural examples of $\mathbf{\Sigma}_1^1$-complete and $\mathbf{\Pi}_1^1$-complete sets. In the first part, we consider ideals on $\omega$. In particular, we show that the Hindman ideal $\mathcal{H}$ is…

Logic · Mathematics 2026-03-09 Łukasz Mazurkiewicz , Szymon Żeberski

Inspired by Bartoszy\'nski's work on small sets, we introduce a new ideal defined by interval partitions on natural numbers and summable sequences of positive reals. Similarly, we present another ideal that relies on Bartoszy\'nski's and…

Logic · Mathematics 2025-02-13 Miguel A. Cardona , Adam Marton , Jaroslav Supina

The theme here is category-measure duality, in the context of a topological group. One can often handle the (Baire) category case and the (Lebesgue, or Haar) measure cases together, by working bi-topologically: switching between the…

General Topology · Mathematics 2017-11-09 N. H. Bingham , A. J. Ostaszewski

In this manuscript a recent topology on the positive integers generated by the collection of $\{\sigma_n:n\in\mathbb{N}\}$ where $\sigma_n:=\{m: \gcd(n,m)=1\}$ is generalized over integral domains. Some of its topological properties are…

General Topology · Mathematics 2024-10-30 Jhixon Macías

Given a collection of $t$ subspaces in an $n$-dimensional $\mathbb{K} $-vector space $W$ we can associate to them $t$ vanishing ideals in the symmetric algebra $\mathcal{S}(W^*) = \mathbb{K}[x_1,x_2,\dots,x_n]$. As a subspace is defined by…

Commutative Algebra · Mathematics 2019-06-25 Francesca Gandini

We introduce the concept of super universality in quantum Hall and spin liquids which has emerged from previous studies. It states that all the fundamental features of the quantum Hall effect are generically displayed as general topological…

Strongly Correlated Electrons · Physics 2009-11-11 A. M. M. Pruisken , R. Shankar , Naveen Surendran

A novel selection principle was introduced by Dorantes-Aldama and Shakhmatov: a topological space $X$ is termed {\em selectively pseudocompact} if for any sequence $(U_n:n\in {\omega})$ of pairwise disjoint non-empty open sets of $X$, one…

General Topology · Mathematics 2025-10-21 István Juhász , Lajos Soukup , Zoltán Szentmiklóssy

Assume that there is no quasi-measurable cardinal smaller than $2^\omega$. ($\kappa$ is quasi measurable if there exists $\kappa $-additive ideal $\ci $ of subsets of $\kappa $ such that the Boolean algebra $P(\kappa)/\ci$ satisfies c.c.c.)…

Logic · Mathematics 2010-03-05 Robert Ralowski , Szymon Zeberski

On the space of isometric embeddings $f_g$ of metrics $g$ on a manifold $M^n$ into the standard $(\mb{S}^{\tn=\tn(n)},\tg)$, we consider the total exterior scalar curvature $\Theta_{f_g}(M)$, and squared $L^2$ norm of the mean curvature…

Differential Geometry · Mathematics 2025-10-01 Santiago R. Simanca

Given a finite subset $\Sigma\subset\mathbb{R}$ and a positive real number $q<1$ we study topological and measure-theoretic properties of the self-similar set $K(\Sigma;q)=\big\{\sum_{n=0}^\infty…

General Topology · Mathematics 2016-02-19 Taras Banakh , Artur Bartoszewicz , Malgorzata Filipczak , Emilia Szymonik

We establish a pointwise limit theorem for a broad class of pa\-ra\-me\-ter-\-de\-pen\-dent BMO-type seminorms as the parameter tends to zero. By introducing novel BMO-type seminorms, we provide a unified framework that extends several…

Functional Analysis · Mathematics 2026-03-30 Konstantinos Bessas , Serena Guarino Lo Bianco , Roberta Schiattarella

If $I$ is an ideal in the ring $C(X)$ of all real valued continuous functions defined over a Tychonoff space $X$, then $X$ is called $I$-$pseudocompact$ if the set $X\setminus \bigcap Z[I]$ is a bounded subset of $X$. Corresponding to $I$,…

General Topology · Mathematics 2026-01-29 Soumajit Dey , Sudip Kumar Acharyya , Dhananjoy Mandal

In this paper, it is shown that every right $\omega$-narrow strongly topological gyrogroup $G$ is right $\omega$-balanced by applying the gyrosemidirect product groups. Then we investigate the class of $\sigma$-compact strongly topological…

General Topology · Mathematics 2026-05-25 Shumin Lai , Fucai Lin

We characterize Markov lattice semigroups induced by measurable semiflows on probability spaces by properties of their generators. In addition we construct topological models on compact spaces for such semigroups.

Dynamical Systems · Mathematics 2020-10-15 Nikolai Edeko , Moritz Gerlach , Viktoria Kühner

We introduce the notion of W-measurable sensitivity, which extends and strictly implies canonical measurable sensitivity, a measure- theoretic version of sensitive dependence on initial conditions. This notion also implies pairwise…

Dynamical Systems · Mathematics 2012-08-20 Ilya Grigoriev , Nathaniel Ince , Marius Catalin Iordan , Amos Lubin , Cesar E. Silva

In this paper, we introduce a new notion of amenability, $\sigma-$Connes ideal, say, for a large class of dual Banach algebras. We extend the concept of ideal Connes amenability and study their properties. Let $\sigma$ be a…

Functional Analysis · Mathematics 2022-01-19 Ali Rejali , Ahmad Minapoor

In this article, we consider $\mathcal{I}^\mathcal{K}$-convergence to define a new concept of convergence namely, $\mathcal{S}$-$\mathcal{I}^\mathcal{K}$-convergence which generalizes the notion of $\mathcal{S}$-$\mathcal{I}$-convergence…

General Topology · Mathematics 2021-04-07 Ankur Sharmah , Debajit Hazarika

Let $\mathcal{E}$ be the ideal generated by the $F_\sigma$ measure zero subsets of the reals. The purpose of this survey paper is to study the cardinal characteristics (the additivity, covering number, uniformity, and cofinality) of…

Logic · Mathematics 2024-02-15 Miguel A. Cardona

A construction of gauge-invariant observables is suggested for a class of topological field theories, the AKSZ sigma-models. The observables are associated to extensions of the target Q-manifold of the sigma model to a Q-bundle over it with…

Mathematical Physics · Physics 2012-12-27 Pavel Mnev