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We provide a characterization of graded von Neumann regular rings involving the recently introduced class of nearly epsilon-strongly graded rings. As our main application, we generalize Hazrat's result that Leavitt path algebras over fields…

Rings and Algebras · Mathematics 2019-10-24 Daniel Lännström

In sharp contrast to the Abrams-Rangaswamy Theorem that the only von Neumann regular Leavitt path algebras are exactly those associated to acyclic graphs, here we prove that the Leavitt path algebra of any arbitrary graph is a graded von…

Rings and Algebras · Mathematics 2013-05-08 Roozbeh Hazrat

For a unital ring, it is an open question whether flatness of simple modules implies all modules are flat and thus the ring is von Neumann regular. The question was raised by Ramamurthi over 40 years ago who called such rings SF-rings…

Rings and Algebras · Mathematics 2018-03-06 A. A. Ambily , Roozbeh Hazrat , Huanhuan Li

We completely characterize when the algebra of an ample groupoid with coefficients in an arbitrary unital ring is von Neumann regular and, more generally, when the algebra of a graded ample groupoid is graded von Neumann regular. Our main…

Rings and Algebras · Mathematics 2025-05-13 Benjamin Steinberg , Daniel W. van Wyk

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 this article, we realize ultragraph Leavitt path algebras as Steinberg algebras. This realization allows us to use the groupoid approach to obtain structural results about these algebras. Using skew product groupoid, we show that…

Rings and Algebras · Mathematics 2020-08-12 R. Hazrat , T. G. Nam

Let $E$ be a directed graph, $\mathbb K$ be a field, and $\mathbb F$ be the free group on the edges of $E$. In this work, we use the isomorphism between Leavitt path algebras and partial skew group rings to endow $L_{\mathbb K}(E)$ with an…

Rings and Algebras · Mathematics 2023-06-29 Daniel Gonçalves , Laura Orozco , Héctor Pinedo

In this article, we give a complete characterization of semigroup graded rings which are graded von Neumann regular. We also demonstrate our results by applying them to several classes of examples, including matrix rings and groupoid graded…

Rings and Algebras · Mathematics 2022-11-30 Daniel Lännström , Johan Öinert

Given a directed graph $E$ and an associative unital ring $R$ one may define the Leavitt path algebra with coefficients in $R$, denoted by $L_R(E)$. For an arbitrary group $G$, $L_R(E)$ can be viewed as a $G$-graded ring. In this article,…

Rings and Algebras · Mathematics 2019-06-20 Patrik Nystedt , Johan Öinert

In this paper, we give a complete characterization of Leavitt path algebras which are graded $\Sigma $-$V$ rings, that is, rings over which a direct sum of arbitrary copies of any graded simple module is graded injective. Specifically, we…

Rings and Algebras · Mathematics 2017-10-19 Roozbeh Hazrat , Kulumani M. Rangaswamy , Ashish K. Srivastava

Let $G$ be a group with identity element $e$, and suppose that $S$ is an associative $G$-graded ring that is not necessarily unital. In the case where $G$ is an ordered group, we show that a graded ideal is prime if and only if it is graded…

Rings and Algebras · Mathematics 2025-10-31 Daniel Lännström , Patrik Lundström , Johan Öinert , Stefan Wagner

We show how to reconstruct a graded ample Hausdorff groupoid with topologically principal neutrally graded component from the ring structure of its graded Steinberg algebra over any commutative integral domain with 1, together with the…

Rings and Algebras · Mathematics 2020-02-25 Pere Ara , Joan Bosa , Roozbeh Hazrat , Aidan Sims

Let $G$ be a group with neutral element $e$ and let $S=\bigoplus_{g \in G}S_g$ be a $G$-graded ring. A necessary condition for $S$ to be noetherian is that the principal component $S_e$ is noetherian. The following partial converse is…

Rings and Algebras · Mathematics 2018-08-31 Daniel Lännström

We show the reduced $C^*$-algebra of a graded ample groupoid is a strongly graded $C^*$-algebra if and only if the corresponding Steinberg algebra is a strongly graded ring. We apply this result to get a theorem about the Leavitt path…

Operator Algebras · Mathematics 2020-04-21 Lisa Orloff Clark , Ellis Dawson , Iain Raeburn

Let $R$ be a unital ring, let $E$ be a directed graph and recall that the Leavitt path algebra $L_R(E)$ carries a natural $\mathbb{Z}$-gradation. We show that $L_R(E)$ is strongly $\mathbb{Z}$-graded if and only if $E$ is row-finite, has no…

Rings and Algebras · Mathematics 2021-01-21 Patrik Lundström , Johan Öinert

Let $\alpha=(A_g,\alpha_g)_{g\in G}$ be a group-type partial action of a connected groupoid $G$ on a ring $A=\bigoplus_{z\in G_0}A_z$ and $B=A\star_{\alpha}G$ the corresponding partial skew groupoid ring. In the first part of this paper we…

Rings and Algebras · Mathematics 2021-03-09 Dirceu Bagio , Víctor Marín , Héctor Pinedo

We study the category of left unital graded modules over the Steinberg algebra of a graded ample Hausdorff groupoid. In the first part of the paper, we show that this category is isomorphic to the category of unital left modules over the…

K-Theory and Homology · Mathematics 2018-04-04 Pere Ara , Roozbeh Hazrat , Huanhuan Li , Aidan Sims

In this work we realize Leavitt path algebras as partial skew groupoid rings. This yields a free path groupoid grading on Leavitt path algebras. Using this grading we characterize free path groupoid graded isomorphisms of Leavitt path…

Rings and Algebras · Mathematics 2015-11-18 Daniel Goncalves , Gabriela Yoneda

We obtain a complete structural characterization of Cohn-Leavitt algebras over no-exit objects as graded involutive algebras. Corollaries of this result include graph-theoretic conditions characterizing when a Leavitt path algebra is a…

Rings and Algebras · Mathematics 2020-04-08 Lia Vas

Given a graded ample Hausdorff groupoid, we realise its graded Steinberg algebra as a partial skew inverse semigroup ring. We use this to show that for a partial action of a discrete group on a locally compact Hausdorff topological space,…

Rings and Algebras · Mathematics 2017-08-18 Roozbeh Hazrat , Huanhuan Li
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