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We prove that any closed map between metrizable spaces can be extended to a closed map between completely metrizable spaces with the same extensional dimension.

General Topology · Mathematics 2007-05-23 H. Murat Tuncali , E. D. Tymchatin , Vesko Valov

In this paper, we study the properties of closure operators obtained as initial lifts along a reflector, and compactness with respect to them in particular. Applications in the areas of topology, topological groups and topological…

Category Theory · Mathematics 2007-05-23 Gábor Lukács

The introduction of the categorical notion of closure operators has unified various important notions and has led to interesting examples and applications in diverse areas of mathematics (see for example, Dikranjan and Tholen (\cite{DT})).…

Category Theory · Mathematics 2010-10-22 Joaquin Luna-Torres , Carlos Orlando Ochoa C

The tractability of certain CSPs for dense or sparse instances is known from the 90s. Recently, the densification and the sparsification of CSPs were formulated as computational tasks and the systematical study of their computational…

Computational Complexity · Computer Science 2022-11-22 Rustem Takhanov

We continue our study of operator algebras with and contractive approximate identities (cais). In earlier papers we have introduced and studied a new notion of positivity in operator algebras, with an eye to extending certain C*-algebraic…

Operator Algebras · Mathematics 2014-07-08 David P. Blecher , Charles John Read

A map between operator spaces is called completely coarse if the sequence of its amplifications is equi-coarse. We prove that all completely coarse maps must be $\mathbb R$-linear. On the opposite direction of this result, we introduce a…

Operator Algebras · Mathematics 2020-06-02 Bruno M. Braga , Javier Alejandro Chávez-Domínguez

For every closed subset $X$ of a stratifiable [resp. metrizable] space $Y$ we construct a positive linear extension operator $T:R^{X\times X}\to R^{Y\times Y}$ preserving constant functions, bounded functions, continuous functions,…

General Topology · Mathematics 2012-02-08 Taras Banakh , Czeslaw Bessaga

In this paper, we study some properties of the closure operator in the Mac\'ias topology on infinite integral domains. Moreover, under certain conditions, we present topological proofs of the infiniteness of maximal ideals and…

Algebraic Topology · Mathematics 2025-06-27 Jhixon Macías , Reyes Ortiz

We introduce the notion of implicative algebra, a simple algebraic structure intended to factorize the model constructions underlying forcing and realizability (both in intuitionistic and classical logic). The salient feature of this…

Logic · Mathematics 2020-07-15 Alexandre Miquel

We define a construction on operads which yields a new description of the minimal model. The construction also allows us to define algebraic structures on the homology of chain complexes with homologously trivial operad algebra structures,…

Algebraic Topology · Mathematics 2015-08-17 Cole Hugelmeyer

We use a way to extend partial combinatory algebras (pcas) by forcing them to represent certain functions. In the case of Scott's Graph model, equality is computable relative to the complement function. However, the converse is not true.…

Logic · Mathematics 2016-10-14 Jaap van Oosten , Niels Voorneveld

It is well known that modal satisfiability is PSPACE-complete (Ladner 1977). However, the complexity may decrease if we restrict the set of propositional operators used. Note that there exist an infinite number of propositional operators,…

Computational Complexity · Computer Science 2008-12-18 Edith Hemaspaandra , Henning Schnoor , Ilka Schnoor

We prove two extension theorems for positive maps from operator systems into matrix algebras

Operator Algebras · Mathematics 2018-05-15 Erling Størmer

In this paper, we tailor-make new approximation operators inspired by rough set theory and specially suited for domain theory. Our approximation operators offer a fresh perspective to existing concepts and results in domain theory, but also…

Logic in Computer Science · Computer Science 2023-06-22 Zhiwei Zou , Qingguo Li , Weng Kin Ho

The paper is concerned with the following question: if $A$ and $B$ are two bounded operators between Hilbert spaces $\mathcal{H}$ and $\mathcal{K}$, and $\mathcal{M}$ and $\mathcal{N}$ are two closed subspaces in $\mathcal{H}$, when will…

Functional Analysis · Mathematics 2018-12-03 Marko S. Djikić , Jovana Nikolov Radenković

If $\H$ is a Hilbert space, $A$ is a positive bounded linear operator on $\cH$ and $\cS$ is a closed subspace of $\cH$, the relative position between $\cS$ and $A^{-1}(\cS \orto)$ establishes a notion of compatibility. We show that the…

Functional Analysis · Mathematics 2007-05-23 Gustavo Corach , Alejandra Maestripieri , Demetrio Stojanoff

This article contains a characterization of operator systems $\cS$ with the property that every positive map $\phi:\cS \rightarrow M_n$ is decomposable, as well as an alternate and a more direct proof of a characterization of decomposable…

Operator Algebras · Mathematics 2020-06-23 Sriram Balasubramanian

The central purpose of this article is to establish new inverse and implicit function theorems for differentiable maps with isolated critical points. One of the key ingredients is a discovery of the fact that differentiable maps with…

Classical Analysis and ODEs · Mathematics 2021-04-02 Liangpan Li

A new Hopf operad Ram is introduced, which contains both the well-known Poisson operad and the Bessel operad introduced previously by the author. Besides, a structure of cooperad R is introduced on a collection of algebras given by…

Quantum Algebra · Mathematics 2014-10-01 Frederic Chapoton

We introduce OpSets, an executable framework for specifying and reasoning about the semantics of replicated datatypes that provide eventual consistency in a distributed system, and for mechanically verifying algorithms that implement these…

Distributed, Parallel, and Cluster Computing · Computer Science 2018-05-15 Martin Kleppmann , Victor B. F. Gomes , Dominic P. Mulligan , Alastair R. Beresford