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Building on the work of Avraham, Rubin, and Shelah, we aim to build a variant of the Fra\"iss\'e theory for uncountable models built from finite submodels. With this aim, we generalize the notion of an increasing set of reals to other…

Logic · Mathematics 2023-07-18 Ziemowit Kostana

This article continues the study of computable elementary topology started by the author and T. Grubba in 2009 and extends the author's 2010 study of axioms of computable separation. Several computable T3- and Tychonoff separation axioms…

Logic · Mathematics 2015-07-01 Klaus Weihrauch

We indicate a way of distinguishing between structures, for which, two structures are said to be separable.Being separable implies being non-isomorphic. We show that for any first order theory $T$ in a countable language, if it has an…

Logic · Mathematics 2012-11-28 Mohammad Assem

A separable space is strongly sequentially separable if, for each countable dense set, every point in the space is a limit of a sequence from the dense set. We consider this and related properties, for the spaces of continous and Borel…

General Topology · Mathematics 2019-11-11 Alexander V. Osipov , Piotr Szewczak , Boaz Tsaban

We construct a topos in which the Dedekind reals are countable. The topos arises from a new kind of realizability, which we call parameterized realizability, based on partial combinatory algebras whose application depends on a parameter.…

Logic · Mathematics 2026-04-02 Andrej Bauer , James E. Hanson

In this paper we study the property of separability of functional space with the open-point and bi-point-open topologies.

General Topology · Mathematics 2016-02-15 Alexander V. Osipov

We prove that in the Miller model, every $M$-separable space of the form $C_p(X)$, where $X$ is metrizable and separable, is productively $M$-separable, i.e., $C_p(X)\times Y$ is $M$-separable for every countable $M$-separable $Y$.

Logic · Mathematics 2020-05-26 Dušan Repovš , Lyubomyr Zdomskyy

We prove that, for any topological space $X$ and any metric space $(Y,d)$, the fine topology on the space of continuous functions from $X$ into $Y$ is independent of the metric $d$.

General Topology · Mathematics 2014-01-17 Francisco J. González Acuña

We prove that any complete metric space has a unique decomposition as a direct product of a possibly finite or zero-dimensional Hilbert space and a space that does not split off lines.

Differential Geometry · Mathematics 2025-03-04 Thomas Foertsch , Alexander Lytchak , Elefterios Soultanis

We analyze the effective content of countable, second countable topological spaces by directly calculating the complexity of several topologically defined index sets. We focus on the separation principles, calibrating an arithmetic…

Logic · Mathematics 2025-07-25 Andrew DeLapo , David Gonzalez

We show that the statement ``In every separable pseudometric space there is a maximal non-strictly \delta-separated set.'' implies the axiom of choice for countable families of sets. This gives answers to a question of Dybowski and…

Logic · Mathematics 2026-01-14 Michał Dybowski , Przemyslaw Górka , Paul Howard

We define scoring metrics on separable metric spaces and show that they are always no coarser than the metrics from which they spring.

General Topology · Mathematics 2007-05-23 Kerry M. Soileau

We prove that for any topological space $X$ of countable tightness, each \sigma-convex subspace $\F$ of the space $SC_p(X)$ of scatteredly continuous real-valued functions on $X$ has network weight $nw(\F)\le nw(X)$. This implies that for a…

General Topology · Mathematics 2013-06-04 Taras Banakh , Bogdan Bokalo , Nadiya Kolos

A topological space $X$ is cometrizable if it admits a weaker metrizable topology such that each point $x\in X$ has a (not necessarily open) neighborhood base consisting of metrically closed sets. We study the relation of cometrizable…

General Topology · Mathematics 2020-04-07 Taras Banakh , Yaryna Stelmakh

In a separably connected space any two points are contained in a separable connected subset. We show a mechanism that takes a connected bounded metric space and produces a complete connected metric space whose separablewise components form…

General Topology · Mathematics 2009-03-30 T. Banakh , M. Vovk , M. R. Wójcik

We give a notion of Scott rank for separable metric structures based on the definability of the (metric closures of) automorphism orbits in continuous infinitary logic. This is a continuous analogue of work of Montalb\'an for countable…

Logic · Mathematics 2024-11-05 Diego Bejarano

We introduce the property of countable separation for a locally convex Hausdorff space $X$ and relate it to the existence of a metrizable coarser topology. Building on this, we demonstrate how the separability of $X$ is equivalent to the…

Functional Analysis · Mathematics 2025-10-10 Thomas Ruf

Adapting a homotopy reconstruction theorem for general metric compacta, we show that every countable metric or ultrametric compact space can be topologically reconstructed as the inverse limit of a sequence of finite $T_0$ spaces which are…

General Topology · Mathematics 2024-12-20 Diego Mondéjar

For infinite products of compact spaces, Tychonoff's theorem asserts that their product is compact, in the product topology. Tychonoff's theorem is shown to be equivalent to the axiom of choice. In this paper, we show that any countable…

General Mathematics · Mathematics 2021-11-05 Garimella Sagar , Duggirala Ravi

We conjecture that whenever $M$ is a metric space of density at most continuum, then the space of Lipschitz functions is $w^*$-separable. We prove the conjecture for several classes of metric spaces including all the Banach spaces with a…

Functional Analysis · Mathematics 2025-03-14 Leandro Candido , Marek Cuth , Benjamin Vejnar