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We explore a new connection between synthetic domain theory and Grothendieck topoi related to the distributive lattice classifier. In particular, all the axioms of synthetic domain theory (including the inductive fixed point object and the…

Logic in Computer Science · Computer Science 2025-05-20 Jonathan Sterling , Lingyuan Ye

Let $G$ be a finite group, let $A$ be an infinite-dimensional stably finite simple unital C*-algebra, and let $\alpha \colon G \to \operatorname{Aut} (A)$ be a tracially strictly approximately inner action of $G$ on $A$. Then the radius of…

Operator Algebras · Mathematics 2023-09-01 M. Ali Asadi-Vasfi

We introduce a bivariant version of the Cuntz semigroup as equivalence classes of order zero maps generalizing the ordinary Cuntz semigroup. The theory has many properties formally analogous to KK-theory including a composition product. We…

Operator Algebras · Mathematics 2016-02-08 Joan Bosa , Gabriele Tornetta , Joachim Zacharias

Quantum theory is extremely successful in explaining most physical phenomena, and is not contradicted by any experiment. Yet, the theory has many puzzling features : the occurrence of probabilities, the unclear distinction between the…

Quantum Physics · Physics 2011-06-07 T. P. Singh

We introduce a new algebraic concept of an algebra which is "almost" commutative (more precisely "quasi-commutative differential graded algebra" or ADGQ, in French). We associate to any simplicial set X an ADGQ - called D(X) - and show how…

Algebraic Topology · Mathematics 2007-05-23 Max Karoubi

In the setting of product systems over group-embeddable monoids, we consider nuclearity of the associated Toeplitz C*-algebra in relation to nuclearity of the coefficient algebra. Our work goes beyond the known cases of single…

Operator Algebras · Mathematics 2025-08-27 Elias G. Katsoulis , Marcelo Laca , Camila F. Sehnem

For a number of properties of C*-algebras, including real rank zero, stable rank one, pure infiniteness, residual hereditary infiniteness, the combination of pure infiniteness and the ideal property, the property of being an AT algebra with…

Operator Algebras · Mathematics 2017-10-03 Cornel Pasnicu , N. Christopher Phillips

We introduce a type of zero-dimensional dynamical system (a pair consisting of a totally disconnected compact metrizable space along with a homeomorphism of that space), which we call "fiberwise essentially minimal", and we prove that the…

Operator Algebras · Mathematics 2021-11-24 Paul Herstedt

We establish an Esakia duality for the categories of temporal Heyting algebras and temporal Esakia spaces. This includes a proof of contravariant equivalence and a congruence/filter/closed-upset correspondence. We then study two notions of…

Logic · Mathematics 2025-05-16 David Quinn Alvarez

We study the topological variant of Rokhlin dimension for topological dynamical systems (X,{\alpha},Z^m) in the case where X is assumed to have finite covering dimension. Finite Rokhlin dimension in this sense is a property that implies…

Operator Algebras · Mathematics 2015-03-13 Gabor Szabo

We study the scalar-tensor theory of gravity profoundly in the action level as well as in the thermodynamic level. Contrary to the usual description in the literature about the equivalence in the two conformally connected frames, this paper…

General Relativity and Quantum Cosmology · Physics 2017-05-19 Krishnakanta Bhattacharya , Bibhas Ranjan Majhi

We introduce and study a notion of module nuclear dimension for a $C^{*}$-algebra $A$ which is $C^*$-module over another $C^*$-algebra $\mathfrak A$ with compatible actions. We show that the module nuclear dimension of $A$ is zero if $A$ is…

Operator Algebras · Mathematics 2023-05-30 Massoud Amini

Given a dynamical system $(X, \Gamma)$, the corresponding crossed product $C^*$-algebra $C(X)\rtimes_{r}\Gamma$ is called reflecting, when every intermediate $C^*$-algebra $C^*_r(\Gamma)<\mathcal{A} < C(X)\rtimes_{r}\Gamma$ is of the form…

Operator Algebras · Mathematics 2024-05-07 Tattwamasi Amrutam , Eli Glasner , Yair Glasner

We show that any free action of a connected Lie group of polynomial growth on a finite dimensional locally compact space has finite tube dimension. This is shown to imply that the associated crossed product C*-algebra has finite nuclear…

Operator Algebras · Mathematics 2023-07-28 Ulrik Enstad , Gabriel Favre , Sven Raum

We show that separable, nuclear and strongly purely infinite C*-algebras have finite nuclear dimension. In fact, the value is at most three. This exploits a deep structural result of Kirchberg and R{\o}rdam on strongly purely infinite…

Operator Algebras · Mathematics 2018-01-12 Gabor Szabo

Using free probability constructions involving Cuntz-Pimsner C*-algebras we show that the topological entropy of the free product of two automorphisms is equal to the maximum of the individual entropies. As applications we show that general…

Operator Algebras · Mathematics 2007-05-23 N. P. Brown , K. Dykema , D. Shlyakhtenko

Generalizing the case of the Toeplitz algebra by Brake and Winter, we prove that the nuclear dimension of a C*-algebra extension of C(X) by the compact operators is equal to the dimension of X.

Operator Algebras · Mathematics 2023-09-28 Ruaridh Gardner , Aaron Tikuisis

For an action of a finite group on a C*-algebra, we present some conditions under which properties of the C*-algebra pass to the crossed product or the fixed point algebra. We mostly consider the ideal property, the projection property,…

Operator Algebras · Mathematics 2012-08-21 Cornel Pasnicu , N. Christopher Phillips

In this paper, we study almost finiteness and almost finiteness in measure of non-free actions. Let $\alpha:G\curvearrowright X$ be a minimal action of a locally finite-by-virtually $\mathbb{Z}$ group $G$ on the Cantor set $X$. We prove…

Operator Algebras · Mathematics 2024-05-28 Kang Li , Xin Ma

We extend the classical Feferman-Vaught theorem to logic for metric structures. This implies that the reduced powers of elementarily equivalent structures are elementarily equivalent, and therefore they are isomorphic under the Continuum…

Logic · Mathematics 2016-04-06 Saeed Ghasemi