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A Leavitt labelled path algebra over a commutative unital ring is associated with a labelled space, generalizing Leavitt path algebras associated with graphs and ultragraphs as well as torsion-free commutative algebras generated by…

Rings and Algebras · Mathematics 2021-06-14 Giuliano Boava , Gilles G. de Castro , Daniel Gonçalves , Daniel W. van Wyk

We investigate the algebra of a Hausdorff ample groupoid, introduced by Steinberg, over a commutative semiring S. In particular, we obtain a complete characterization of congruence-simpleness for such Steinberg algebras, extending the…

Rings and Algebras · Mathematics 2020-08-24 Tran Giang Nam , Jens Zumbrägel

A ring $R$ satisfies the {\it strong rank condition} (SRC) if, for every natural number $n$, the free $R$-submodules of $R^n$ all have rank $\leq n$. Let $G$ be a group and $R$ a ring strongly graded by $G$ such that the base ring $R_1$ is…

Rings and Algebras · Mathematics 2019-08-16 Peter Kropholler , Karl Lorensen

Various authors have been generalizing some unital ring properties to nonunital rings. We consider properties related to cancellation of modules (being unit-regular, having stable range one, being directly finite, exchange, or clean) and…

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

In this note we first study regular $\mathbb{Z}$-graded local rings. We characterize commutative noetherian regular $\mathbb{Z}$-graded local rings in similar ways as in the usual local case. Then, we characterize graded isolated…

Commutative Algebra · Mathematics 2025-08-11 Haonan Li , Quanshui Wu

We realize Leavitt path algebras as partial skew group rings and give new proofs, based on partial skew group ring theory, of the Cuntz-Krieger uniqueness theorem and simplicity criteria for Leavitt path algebras.

Rings and Algebras · Mathematics 2012-02-14 Daniel Gonçalves , Danilo Royer

Given an action of a monoid $T$ on a ring $A$ by ring endomorphisms, and an Ore subset $S$ of $T$, a general construction of a fractional skew monoid ring $S^{\rm op} * A * T$ is given, extending the usual constructions of skew group rings…

Rings and Algebras · Mathematics 2007-05-23 P. Ara , M. A. Gonzalez-Barroso , K. R. Goodearl , E. Pardo

When the theory of Leavitt path algebras was already quite advanced, it was discovered that some of the more difficult questions were susceptible to a new approach using topological groupoids. The main result that makes this possible is…

Rings and Algebras · Mathematics 2019-05-16 Simon W. Rigby

We introduce a graded homology theory for graded \'etale groupoids. For $\mathbb Z$-graded groupoids, we establish an exact sequence relating the graded zeroth-homology to non-graded one. Specialising to the arbitrary graph groupoids, we…

K-Theory and Homology · Mathematics 2019-01-23 Roozbeh Hazrat , Huanhuan Li

If $R$ is a regular and semiartinian ring, it is proved that the following conditions are equivalent: (1) $R$ is unit-regular, (2) every factor ring of $R$ is directly finite, (3) the abelian group $K_0(R)$ is free and admits a basis which…

Rings and Algebras · Mathematics 2016-07-14 Giuseppe Baccella , Leonardo Spinosa

In this article we generalize a classical result by Passman on primeness of unital strongly group graded rings to the class of nearly epsilon-strongly group graded rings which are not necessarily unital. Using this result, we obtain (i) a…

Rings and Algebras · Mathematics 2025-12-24 Daniel Lännström , Patrik Lundström , Johan Öinert , Stefan Wagner

Let $R$ be a ring and $S$ a multiplicative subset of $R$. An $R$-module $T$ is called $u$-$S$-torsion ($u$- always abbreviates uniformly) provided that $sT=0$ for some $s\in S$. The notion of $u$-$S$-exact sequences is also introduced from…

Commutative Algebra · Mathematics 2022-01-25 Xiaolei Zhang

We give a one-to-one correspondence between ideals in the Steinberg algebra of a Hausdorff ample groupoid $G$, and certain families of ideals in the group algebras of isotropy groups in $G$. This generalises a known ideal correspondence…

Rings and Algebras · Mathematics 2021-09-20 Simon W. Rigby , Thibaud van den Hove

Suppose that $R$ is an associative unital ring and that $E=(E^0,E^1,r,s)$ is a directed graph. Utilizing results from graded ring theory we show, that the associated Leavitt path algebra $L_R(E)$ is simple if and only if $R$ is simple,…

Rings and Algebras · Mathematics 2022-12-02 Patrik Lundström , Johan Öinert

In this paper, we develop structure theory for graded regular graded self-injective rings and apply it in the context of Leavitt path algebras. We show that for a finite graph, graded regular graded self-injective Leavitt path algebras are…

Rings and Algebras · Mathematics 2018-08-22 Roozbeh Hazrat , Kulumani M. Rangaswamy , Ashish K. Srivastava

While every matrix algebra over a field $K$ can be realized as a Leavitt path algebra, this is not the case for every graded matrix algebra over a graded field. We provide a complete description of graded matrix algebras over a field,…

Rings and Algebras · Mathematics 2025-05-23 Lia Vas

The algebraic Cuntz-Pimsner rings are naturally $\mathbb{Z}$-graded rings that generalize both Leavitt path algebras and unperforated $\mathbb{Z}$-graded Steinberg algebras. We classify strongly, epsilon-strongly and nearly epsilon-strongly…

Rings and Algebras · Mathematics 2019-09-24 Daniel Lännström

We study strongly graded groupoids, which are topological groupoids $\mathcal G$ equipped with a continuous, surjective functor $\kappa: \mathcal G \to \Gamma$, to a discrete group $\Gamma$, such that $\kappa^{-1}(\gamma)\kappa^{-1}(\delta)…

Rings and Algebras · Mathematics 2018-08-17 Lisa Orloff Clark , Roozbeh Hazrat , Simon W. Rigby

Let E be an arbitrary directed graph with no restrictions on the number of vertices and edges and let K be any field. We give necessary and sufficient conditions for the Leavitt path algebra L_K(E) to be of countable irreducible…

Rings and Algebras · Mathematics 2014-06-26 Pere Ara , Kulumani M. Rangaswamy

The main result of this article is a fantastic generalization of a classical result in graded ring theory. In fact, our result states that if $S$ is a multiplicative set of homogeneous elements of an $M$-graded commutative ring…

Commutative Algebra · Mathematics 2026-04-17 Abolfazl Tarizadeh