Johan Öinert

activity

20102026

most citedSimplicity and maximal commutative subalgebras of twisted generalized Weyl algebras

13 citations · 46 across the 21 of their papers we have counts for

collaborators

29 papers

math.RA2026

Invertibility of structured perturbations of singular matrices over unital rings

Johan Öinert

In this article, we study the invertibility of matrices of the form $A + E D F$ , where $A$ and $D$ are square matrices over a unital, not necessarily commutative, ring and $A$ is singu…

math.RA2026

Very good gradings on structural matrix rings

Patrik Lundström, Johan Öinert, Laura Orozco +1

Let $R$ be a nonzero associative unital ring, let $G$ be a group, and let $ρ$ be a preorder on ${1, \dots, n}$ . A $G$ -grading on $ρ$ induces a very good $G$ -grading on the structu…

math.RA2026

Hilbert's basis theorem for Poisson Ore extensions

Per Bäck, Patrik Lundström, Johan Öinert +1

We prove an analogue of Hilbert's basis theorem for Poisson Ore extensions and Poisson Laurent Ore extensions. We also obtain corresponding results for iterated Poisson Ore extensi…

math.RA2024

Rank conditions and amenability for rings associated to graphs

Karl Lorensen, Johan Öinert

We study path rings, Cohn path rings, and Leavitt path rings associated to directed graphs, with coefficients in an arbitrary ring $R$ . For each of these types of rings, we stipula…

math.RA2023

Very good gradings on matrix rings are epsilon-strong

Patrik Lundström, Johan Öinert, Laura Orozco +1

We investigate properties of group gradings on matrix rings $M_{n} (R)$ , where $R$ is an associative unital ring and $n$ is a positive integer. More precisely, we introduce very good…

math.RA2022

Prime groupoid graded rings with applications to partial skew groupoid rings

Paula S. E. Moreira, Johan Öinert

In this paper, we investigate primeness of groupoid graded rings. We provide a set of necessary and sufficient conditions for primeness of a nearly-epsilon strongly groupoid graded…

math.RA2022

The ideal structure of partial skew groupoid rings with applications to topological dynamics and ultragraph algebras

Dirceu Bagio, Daniel Gonçalves, Paula Savana Estácio Moreira +1

Given a partial action $α$ of a groupoid $G$ on a ring $R$ , we study the associated partial skew groupoid ring $R ⋊_{α} G$ , which carries a natural $G$ -grading. We show that th…

math.RA2022

Pure semisimple and Köthe group rings

Samaneh Baghdari, Johan Öinert

In this article we provide a complete characterization of abelian group rings which are Köthe rings. We also provide characterizations of (possibly non-abelian) group rings over di…

math.RA2022

Non-Abelian extensions of groupoids and their groupoid rings

Natã Machado, Johan Öinert, Stefan Wagner

We present a geometrically oriented classification theory for non-Abelian extensions of groupoids generalizing the classification theory for Abelian extensions of groupoids by West…

math.RA2022

Non-unital Ore extensions

Patrik Lundström, Johan Öinert, Johan Richter

In this article, we study Ore extensions of non-unital associative rings. We provide a characterization of simple non-unital differential polynomial rings $R [x; δ]$ , under the hypot…

math.RA2022

Graded von Neumann regularity of rings graded by semigroups

Daniel Lännström, Johan Öinert

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 cla…

math.RA2022

Generating numbers of rings graded by amenable and supramenable groups

Karl Lorensen, Johan Öinert

A ring $R$ has {\it unbounded generating number} (UGN) if, for every positive integer $n$ , there is no $R$ -module epimorphism $R^{n} \to R^{n + 1}$ . For a ring $R=\bigoplus_{g\in G} R_g…

math.RA2021★ 1 cited

Prime group graded rings with applications to partial crossed products and Leavitt path algebras

Daniel Lännström, Patrik Lundström, Johan Öinert +1

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…

math.RA2019

Units, zero-divisors and idempotents in rings graded by torsion-free groups

Johan Öinert

The three famous problems concerning units, zero-divisors and idempotents in group rings of torsion-free groups, commonly attributed to I. Kaplansky, have been around for more than…

math.RA2017★ 3 cited

Simplicity of skew inverse semigroup rings with applications to Steinberg algebras and topological dynamics

Viviane Beuter, Daniel Gonçalves, Johan Öinert +1

Given a partial action $π$ of an inverse semigroup $S$ on a ring $A$ one may construct its associated skew inverse semigroup ring $A ⋊_{π} S$ . Our main resul…

math.RA2017★ 7 cited

Simplicity of Ore monoid rings

Patrik Nystedt, Johan Öinert, Johan Richter

Given a non-associative unital ring $R$ , a monoid $G$ and a set $π$ of additive maps $R \to R$ , we introduce the Ore monoid ring $R [π; G]$ , and, in a special case, the diff…

math.RA2017

Group gradations on Leavitt path algebras

Patrik Nystedt, 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_…

math.RA2016

Simple graded rings, non-associative crossed products and Cayley-Dickson doublings

Patrik Nystedt, Johan Öinert

We show that if a non-associative unital ring is graded by a hypercentral group, then the ring is simple if and only if it is graded simple and the center of the ring is a field. T…

math.RA2016

Quasi-duo differential polynomial rings

Mai Hoang Bien, Johan Öinert

In this article we give a characterization of left (right) quasi-duo differential polynomial rings. In particular, we show that a differential polynomial ring is left quasi-duo if…

math.RA2016

Epsilon-strongly graded rings, separability and semisimplicity

Patrik Nystedt, Johan Öinert, Héctor Pinedo

We introduce the class of epsilon-strongly graded rings and show that it properly contains both the class of strongly graded rings and the class of unital partial crossed products.…

math.RA2016

Artinian and noetherian partial skew groupoid rings

Patrik Nystedt, Johan Öinert, Héctor Pinedo

Let $α = {α_{g} : R_{g^{- 1}} \to R_{g}}_{g \in mor (G)}$ be a partial action of a groupoid $G$ on a non-associative ring $R$ and let $S = R ⋆_{α} G$ be the associa…

math.RA2015

Non-associative Ore extensions

Patrik Nystedt, Johan Öinert, Johan Richter

We introduce non-associative Ore extensions, $S = R [X; σ, δ]$ , for any non-associative unital ring $R$ and any additive maps $σ, δ : R \to R$ satisfying $σ (1) = 1$ and $δ(1)=0…

math.RA2014★ 1 cited

Outer partial actions and partial skew group rings

Patrik Nystedt, Johan Öinert

We extend the classicial notion of an outer action $α$ of a group $G$ on a unital ring $A$ to the case when $α$ is a partial action on ideals, all of which have local units. We sho…

math.RA2013

Simple Semigroup Graded Rings

Patrik Nystedt, Johan Öinert

We show that if $R$ is a, not necessarily unital, ring graded by a semigroup $G$ equipped with an idempotent $e$ such that $G$ is cancellative at $e$ , the non-zero elements of $eGe…