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We prove that continuous reducibility is a well-quasi-order on the class of continuous functions between separable metrizable spaces with analytic zero-dimensional domain. To achieve this, we define scattered functions, which generalize…

Logic · Mathematics 2024-10-18 Raphaël Carroy , Yann Pequignot

We study M-separability as well as some other combinatorial versions of separability. In particular, we show that the set-theoretic hypothesis b=d implies that the class of selectively separable spaces is not closed under finite products,…

General Topology · Mathematics 2010-10-13 Dušan Repovš , Lyubomyr Zdomskyy

A topological space is iso-dense if it has a dense set of isolated points. A topological space is scattered if each of its non-empty subspaces has an isolated point. In $\mathbf{ZF}$, in the absence of the axiom of choice, basic properties…

General Topology · Mathematics 2021-01-11 Kyriakos Keremedis , Eleftherios Tachtsis , Eliza Wajch

The necessary and sufficient conditions for a function to be totally or partially separable are derived. It is shown that a function is totally separable if and only if each component of the gradient vector of depends only on the…

Numerical Analysis · Mathematics 2025-10-20 C. P. Viazminsky

We define covering and separation numbers for functions. We investigate their properties, and show that for some classes of functions there is exact equality of separation and covering. We provide analogues for various geometric…

Functional Analysis · Mathematics 2017-04-25 Shiri Artstein-Avidan , Boaz A. Slomka

The paper deals with Ascoli spaces $C_p(X)$ and $C_k(X)$ over Tychonoff spaces $X$. The class of Ascoli spaces $X$, i.e. spaces $X$ for which any compact subset $K$ of $C_k(X)$ is evenly continuous, essentially includes the class of…

General Topology · Mathematics 2016-06-06 Saak Gabriyelyan , Jan Grebík , Jerzy Kakol , Lyubomyr Zdomskyy

For a Tychonoff space $X$, we denote by $C_p(X)$ the space of all real-valued continuous functions on $X$ with the topology of pointwise convergence. We give the functional characterization of the covering property of Hurewicz.

General Topology · Mathematics 2018-05-31 Alexander V. Osipov

In this short note, we show that the distance function to any finite set $X\subset \mathbb{R}^n$ is a topological Morse function, regardless of whether $X$ is in general position. We also precisely characterize its topological critical…

Differential Geometry · Mathematics 2024-07-23 Charles Arnal

For a Tychonoff space $X$ and a family $\lambda$ of subsets of $X$, we denote by $C_{\lambda}(X)$ the space of all real-valued continuous functions on $X$ with the set-open topology. In this paper, we study the Menger and projective Menger…

General Topology · Mathematics 2018-03-28 Alexander V. Osipov

Constructing a discretization of a given set is a major problem in various theoretical and applied disciplines. An offset discretization of a set $X$ is obtained by taking the integer points inside a closed neighborhood of $X$ of a certain…

Discrete Mathematics · Computer Science 2018-08-10 Boris Brimkov , Valentin E. Brimkov

Functional digraphs are unlabelled finite digraphs where each vertex has exactly one out-neighbor. They are isomorphic classes of finite discrete-time dynamical systems. Endowed with the direct sum and product, functional digraphs form a…

Combinatorics · Mathematics 2026-03-04 Florian Bridoux , Christophe Crespelle , Thi Ha Duong Phan , Adrien Richard

Answering a question of Sakai, we show that the minimal cardinality of a set of reals X such that C_p(X) does not have the Pytkeev property is equal to the pseudo-intersection number p. Our approach leads to a natural characterization of…

General Topology · Mathematics 2010-11-05 Petr Simon , Boaz Tsaban

In this article we studied the relationship between metric spaces and multiplicative metric spaces. Also, we pointed out some fixed and common fixed point results under some contractive conditions in multiplicative metric spaces can be…

General Topology · Mathematics 2015-12-14 K. Abodayeh , A. Pitea , W. Shatanawi , T. Abdeljawad

In a complete metric space that is equipped with a doubling measure and supports a Poincar\'e inequality, we study strict subsets, i.e. sets whose variational capacity with respect to a larger reference set is finite, in the case $p=1$.…

Metric Geometry · Mathematics 2019-03-12 Panu Lahti

In this paper, we investigate the existence and uniqueness of fixed points for self-mappings defined on bipolar metric spaces using a new class of contractive conditions, namely polynomial-type contractions. Our main results establish…

General Topology · Mathematics 2025-08-08 Gopinath Janardhanan , Gunaseelan Mani , Nancy Delaila John Kennedy , Yaé Ulrich Gaba

Let M be a complete metric space. It is proved that if the space or scalar-valued bounded continuous functions on M admits an isometric shift, then M is separable.

Functional Analysis · Mathematics 2007-05-23 Jesus Araujo , Juan J. Font

We prove that each coarsely homogenous separable metric space $X$ is coarsely equivalent to one of the spaces: the sigleton, the Cantor macro-cube or the Baire macro-space. This classification is derived from coarse characterizations of the…

Metric Geometry · Mathematics 2011-10-11 Taras Banakh , Ihor Zarichnyi

We study spaces $X$ for which the space $Hom_p(X)$ of automorphisms with the topology of point-wise convergence is a topological group. We identify large classes of spaces $X$ for which $Hom_p(X)$ is or is not a topological group.

General Topology · Mathematics 2024-06-28 Raushan Buzyakova

We develop new tools for the construction of fixed point sets in digital topology. We define excludable points and show that these may be excluded from all freezing sets. We show that articulation points are excludable. We also present…

Geometric Topology · Mathematics 2024-06-11 Laurence Boxer

In this paper, we introduce concepts of separable functions in balls and in the whole space, and develop a new method to investigate the qualitative properties of separable functions. We first study the axial symmetry and monotonicity of…

Analysis of PDEs · Mathematics 2018-09-18 Tao Wang , Taishan Yi