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Let $(\mathcal{G},\nu)$ be a $t$-discrete ergodic groupoid. Consider a finite Von Neumann algebra $\mathcal{M}$ with separable predual. We prove that every uniformly bounded measurable representation $\rho:\mathcal{G} \rightarrow…

Operator Algebras · Mathematics 2025-12-29 Alessio Savini

Starting with a spectral triple on a unital $C^{*}$-algebra $A$ with an action of a discrete group $G$, if the action is uniformly bounded (in a Lipschitz sense) a spectral triple on the reduced crossed product $C^{*}$-algebra $A\rtimes_{r}…

Operator Algebras · Mathematics 2022-08-30 P. Antonini , D. Guido , T. Isola , A. Rubin

We classify subalgebras of a ring of differential operators which are big in the sense that the extension of associated graded rings is finite. We show that these subalgebras correspond, up to automorphisms, to uniformly ramified finite…

Rings and Algebras · Mathematics 2007-05-23 Friedrich Knop

The extending structures and unified products for Zinbiel algebras are developed. Some special cases of unified products such as crossed products and matched pair of Zinbiel algebras are studied. It is proved that the extending structures…

Rings and Algebras · Mathematics 2023-01-03 Tao Zhang , Ling Zhang

A valuation theoretic approach is presented that directly leads to division algebras that are noncrossed products (instead of, e.g., describing Brauer classes of noncrossed products in an abstract manner). While this feature is shared by…

Rings and Algebras · Mathematics 2011-09-09 Timo Hanke

We study groups and rings definable in d-minimal expansions of ordered fields. We generalize to such objects some known results from o-minimality. In particular, we prove that we can endow a definable group with a definable topology making…

Logic · Mathematics 2021-07-12 Antongiulio Fornasiero

Let $\Gamma$ be a countable group that admits an essential measurable splitting (for instance, any group measure equivalent to a free product of nontrivial groups). We show: (1) for any two nontrivial countable groups $B$ and $C$ that are…

Group Theory · Mathematics 2024-11-22 Robin Tucker-Drob , Konrad Wróbel

The extending structures and unified products for Malcev algebras are developed. Some special cases of unified products such as crossed products and matched pair of Malcev algebras are studied. It is proved that the extending structures can…

Rings and Algebras · Mathematics 2021-08-24 Tao Zhang , Ling Zhang , Ruyi Xie

In order to simultaneously generalize matrix rings and group graded crossed products, we introduce category crossed products. For such algebras we describe the center and the commutant of the coefficient ring. We also investigate the…

Rings and Algebras · Mathematics 2008-12-09 Johan Öinert , Patrik Lundström

This paper presents an extension of the concept of NR-clean introduced in [12] to graded ring theory. We define and explore graded NR-clean rings, which generalize the class of graded U-nil clean previously studied in [15]. We provide…

Commutative Algebra · Mathematics 2024-01-23 Ismail Namrok

In this article, we consider the structure of graded rings, not necessarily commutative nor with unity, and study the graded weakly prime ideals. We investigate the graded rings in which all graded ideals are graded weakly prime. Several…

Rings and Algebras · Mathematics 2021-01-07 Azzh Saad Alshehry , Rashid Abu-Dawwas

We classify Galois objects for the dual of a group algebra of a finite group over an arbitrary field.

Quantum Algebra · Mathematics 2010-06-22 Cesar Galindo , Manuel Medina

We raise the following general question regarding a ring graded by a group: "If $P$ is a ring-theoretic property, how does one define the graded version $P_{\operatorname{gr}}$ of the property $P$ in a meaningful way?". Some properties of…

Rings and Algebras · Mathematics 2023-12-05 Lia Vas

In the paper we study the algebroid A of the groupoid of partially invertible elements over the lattice of orthogonal projections of a $W^*$-algebra. In particular the complex analytic manifold structure of these objects is investigated.…

Differential Geometry · Mathematics 2015-12-09 Anatol Odzijewicz , Grzegorz Jakimowicz , Aneta Sliżewska

We investigate one question regarding bicrossed products of finite groups which we believe has the potential of being approachable for other classes of algebraic objects (algebras, Hopf algebras). The problem is to classify the groups that…

Group Theory · Mathematics 2014-03-18 A. L. Agore , A. Chirvasitu , B. Ion , G. Militaru

An $S$-ring (a Schur ring) is said to be separable with respect to a class of groups $\mathcal{K}$ if every algebraic isomorphism from the $S$-ring in question to an $S$-ring over a group from $\mathcal{K}$ is induced by a combinatorial…

Combinatorics · Mathematics 2020-12-29 Grigory Ryabov

Let $(\mathcal{A}, G, \alpha)$ be a groupoid dynamical system. We show that if $G$ is assumed to be measurewise amenable and the section algebra $A = \Gamma_0(G^{(0)}, \mathcal{A})$ is nuclear, then the associated groupoid crossed product…

Operator Algebras · Mathematics 2014-06-09 Scott M. LaLonde

We introduce and develop a structure theory of a new class of noncommutative rings - Galois orders, that generalize classical orders in noncommutative rings. Galois orders realized as certain subrings of invariants in skew semigroup rings.…

Representation Theory · Mathematics 2008-09-16 Vyacheslav Futorny , Serge Ovsienko

We define special objects, Ulrich objects, on a derived category of polarized smooth projective variety as a generalization of Ulrich bundles to the derived category. These are defined by the cohomological conditions that are the same form…

Algebraic Geometry · Mathematics 2025-09-17 Tomoki Yoshida

We give a unified description of twisted forms of classical reductive groups schemes. Such group schemes are constructed from algebraic objects of finite rank, excluding some exceptions of small rank. These objects, augmented odd form…

Group Theory · Mathematics 2026-05-08 Egor Voronetsky