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We construct a fully faithful functor from the category of graphs to the category of fields. Using this functor, we resolve a longstanding open problem in computable model theory, by showing that for every nontrivial countable structure S,…

Logic · Mathematics 2015-10-27 Russell Miller , Bjorn Poonen , Hans Schoutens , Alexandra Shlapentokh

We characterize coset spaces of topological groups which are coset spaces of (separable) metrizable groups and complete metrizable (Polish) groups. Besides, it is shown that for a $G$-space $X$ with a $d$-open action there is a topological…

General Topology · Mathematics 2017-11-29 Sergey Antonyan , Natella Antonyan , Konstantin Kozlov

Function space topologies are developed for EC(Y,Z), the class of equi-continuous mappings from a topological space Y to a uniform space Z. Properties such as splittingness, admissibility etc. are defined for such spaces. The net theoretic…

General Mathematics · Mathematics 2020-01-03 Ankit Gupta , Ratna Dev Sarma

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

The dynamics of symbolic systems, such as multidimensional subshifts of finite type or cellular automata, are known to be closely related to computability theory. In particular, the appropriate tools to describe and classify topological…

Dynamical Systems · Mathematics 2019-06-06 Silvere Gangloff , Alonso Herrera , Cristobal Rojas , Mathieu Sablik

By analogy with the Cayley graph of a group with respect to a finite generating set or the Cayley--Abels graph of a totally disconnected, locally compact group, we detail countable connected graphs associated to Polish groups that we term…

Group Theory · Mathematics 2025-05-16 Beth Branman , George Domat , Hannah Hoganson , Robert Alonzo Lyman

Given a computably locally compact Polish space $M$, we show that its 1-point compactification $M^*$ is computably compact. Then, for a computably locally compact group $G$, we show that the Chabauty space $\mathcal S(G)$ of closed…

Group Theory · Mathematics 2024-07-30 Alexander G. Melnikov , Andre Nies

Some notions in mathematics can be considered relative. Relative is a term used to denote when the variation in the position of an observer implies variation in properties or measures on the observed object. We know, from Skolem theorem,…

Logic in Computer Science · Computer Science 2016-03-04 Edward Hermann Haeusler

In first order logic, it is known that you can define a topology so that the countable models of some theory $T$ form a Polish Space (i.e. completely metrizable second countable space). In this paper we use the Baldwin- Boney Relational…

Logic · Mathematics 2025-03-31 Georgios Marangelis

We begin to study classical dimension theory from the computable analysis (TTE) point of view. For computable metric spaces, several effectivisations of zero-dimensionality are shown to be equivalent. The part of this characterisation that…

Logic · Mathematics 2015-07-01 Robert Kenny

A compact topological space X is spectral if it is sober (i.e., every irreducible closed set is the closure of a unique singleton) and the compact open subsets of X form a basis of the topology of X, closed under finite intersections.…

Rings and Algebras · Mathematics 2017-12-01 Friedrich Wehrung

Through the subsequent discussion we consider a certain particular sort of (topological) algebras, which may substitute the `` structure sheaf algebras'' in many--in point of fact, in all--the situations of a geometrical character that…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Anastasios Mallios

Computational topology is an area that revisits topological problems from an algorithmic point of view, and develops topological tools for improved algorithms. We survey results in computational topology that are concerned with graphs drawn…

Computational Geometry · Computer Science 2017-09-06 Éric Colin de Verdière

In this article, we identify a suitable approach to define the character space of a commutative unital locally $C^{\ast}$-algebra via the notion of the inductive limit of topological spaces. Also, we discuss topological properties of the…

Operator Algebras · Mathematics 2024-09-04 Santhosh Kumar Pamula , Rifat Siddique

We investigate some basic descriptive set theory for countably based completely quasi-metrizable topological spaces, which we refer to as quasi-Polish spaces. These spaces naturally generalize much of the classical descriptive set theory of…

Logic · Mathematics 2012-11-07 Matthew de Brecht

Whole Tale http://wholetale.org is a web-based, open-source platform for reproducible research supporting the creation, sharing, execution, and verification of "Tales" for the scientific research community. Tales are executable research…

We introduce the notion of a "graded topological space": a topological space endowed with a sheaf of abelian groups which we think of as a sheaf of gradings. Any object living on a graded topological space will be graded by this sheaf of…

Algebraic Geometry · Mathematics 2020-07-20 Clemens Koppensteiner

We show that the category of decomposition spaces and CULF maps is locally a topos. Precisely, the slice category over any decomposition space D is a presheaf topos, namely decomp/D=Psh(tw D).

Category Theory · Mathematics 2019-09-04 Joachim Kock , David I. Spivak

Using tools from computable analysis we develop a notion of effectiveness for general dynamical systems as those group actions on arbitrary spaces that contain a computable representative in their topological conjugacy class. Most natural…

Dynamical Systems · Mathematics 2024-09-16 Sebastián Barbieri , Nicanor Carrasco-Vargas , Cristóbal Rojas

Building on our prior work on axiomatization of exact real computation by formalizing nondeterministic first-order partial computations over real and complex numbers in a constructive dependent type theory, we present a framework for…

Logic in Computer Science · Computer Science 2024-10-18 Michal Konečný , Sewon Park , Holger Thies