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In this paper we discuss several constructions that lead to new examples of nil-clean, clean, and exchange rings. A characterization of the idempotents in the algebra defined by a 2-cocycle is given and used to prove some of the algebra's…

Rings and Algebras · Mathematics 2014-04-11 Alin Stancu

Symmetric rings were introduced by Lambek to extend usual commutative ideal theory in noncommutative rings. In this paper, we study symmetric rings over which Ore extensions are symmetric. A ring R is called strongly \sigma-symmetric if the…

Rings and Algebras · Mathematics 2018-12-27 Fatma Kaynarca , H. Melis Tekin Akcin

A ring is clean (almost clean) if each of its elements is the sum of a unit (regular element) and an idempotent. A module is clean (almost clean) if its endomorphism ring is clean (almost clean). We show that every quasi-continuous and…

Rings and Algebras · Mathematics 2013-05-10 Evrim Akalan , Lia Vas

A dessin is a 2-cell embedding of a connected $2$-coloured bipartite graph into an orientable closed surface. A dessin is regular if its group of orientation- and colour-preserving automorphisms acts regularly on the edges. In this paper we…

Combinatorics · Mathematics 2018-06-20 Yan-Quan Feng , Kan Hu , Roman Nedela , Martin Skoviera , Na-Er Wang

We investigate finiteness conditions on modules of bounded projective dimension and their connection with generalized notions of coherence. For a ring $R$, we consider the class $\mathsf{FP}_n^{\le d}(R)$ of finitely $n$-presented modules…

Rings and Algebras · Mathematics 2026-04-22 Rafael Parra

In this paper, we study a new class of rings, called $\sqrt{J}$-clean rings. A ring in which every element can be expressed as the addition of an idempotent and an element from $\sqrt{J(R)}$ is called a $\sqrt{J}$-clean ring. Here,…

Rings and Algebras · Mathematics 2025-10-30 Dinesh Udar , Shiksha Saini

{Generalizing the notion of nil cleanness from \cite{D13}, in parallel to \cite{DM14}, we define the concept of {\it weak nil cleanness} for an arbitrary ring. Its comprehensive study in different ways is provided as well. A decomposition…

Rings and Algebras · Mathematics 2014-12-18 Simion Breaz , Peter Danchev , Yiqiang Zhou

We define the class of {\it unit uniquely clean} rings ({\it UnitUC} for short), that is a common generalization of uniquely clean rings and strongly nil clean rings. Abelian {\it UnitUC} rings are uniquely clean and {\it UnitUC} rings with…

Rings and Algebras · Mathematics 2025-09-23 Mina Doostalizadeh , Ahmad Moussavi , Peter Danchev

This paper unifies several generalizations of coherent rings in one notion. Namely, we introduce $n$-$\mathscr{X}$-coherent rings, where $\mathscr{X}$ is a class of modules and $n$ is a positive integer, as those rings for which the…

Rings and Algebras · Mathematics 2010-01-26 Driss Bennis

We introduce the concept of a weak nil clean ring, a generalization of nil clean ring, which is nothing but a ring with unity in which every element can be expressed as sum or difference of a nilpotent and an idempotent. Further if the…

Rings and Algebras · Mathematics 2015-10-27 Dhiren Kumar Basnet , Jayanta Bhattacharyya

In this paper, we introduce the concept of N-pure ideal as a generalization of pure ideal. Using this concept, a new and interesting type of rings is presented, we call it mid ring. Also, we provide new characterizations for von Neumann…

Commutative Algebra · Mathematics 2021-01-28 Mohsen Aghajani

In this paper we introduce and study the notion of a graded (strongly) nil clean ring which is group graded. We also deal with extensions of graded (strongly) nil clean rings to graded matrix rings and to graded group rings. The question of…

Rings and Algebras · Mathematics 2019-04-05 Emil Ilić-Georgijević , Serap Şahinkaya

We characterize the nil clean matrix rings over fields. As a by product, it is proved that the full matrix rings with coefficients in commutative nil-clean rings are nil-clean, and we obtain a complete characterization of the finite rank…

Commutative Algebra · Mathematics 2013-10-02 S. Breaz , G. Călugăreanu , P. Danchev , T. Micu

Two elements $a,b$ in a ring $R$ form a right coprime pair, written $\langle a,b\rangle$, if $aR+bR=R$. Right coprime pairs have shown to be quite useful in the study of left cotorsion or exchange rings. In this paper, we define the class…

Rings and Algebras · Mathematics 2022-01-19 Manuel Cortés-Izurdiaga , Pedro A. Guil Asensio

An element of a ring R is called clean if it is the sum of an idempotent and a unit. A ring R is called clean if each of its element is clean. An element r \in R called regular if r = ryr for some y \in R. The ring R is regular if each of…

Rings and Algebras · Mathematics 2011-05-04 Nahid Ashrafi , Ebrahim Nasibi

A longstanding open question is whether every strongly clean ring (ring in which every element is strongly clean, i.e., is the sum of an idempotent and a unit which commute with each other) is Dedekind-finite (has the property that every…

Rings and Algebras · Mathematics 2025-08-21 George M. Bergman

A *-ring $R$ is called a strongly nil-*-clean ring if every element of $R$ is the sum of a projection and a nilpotent element that commute with each other. In this article, we show that $R$ is a strongly nil-*-clean ring if and only if…

Rings and Algebras · Mathematics 2013-09-06 Huanyin Chen , Abdullah Harmanci , A. Cigdem Ozcan

A ring $R$ is called strongly clean if every element of $R$ is the sum of a unit and an idempotent that commute. By {\rm SRC} factorization, Borooah, Diesl, and Dorsey \cite{BDD051} completely determined when ${\mathbb M}_n(R)$ over a…

Rings and Algebras · Mathematics 2008-08-20 Lingling Fan , Xiande Yang

Motivated by the concept of clean ideals, we introduce the notion of nil clean ideals of a ring. We define an ideal $I$ of a ring $R$ to be nil clean ideal if every element of $I$ can be written as a sum of an idempotent and a nilpotent…

Rings and Algebras · Mathematics 2017-09-08 Ajay Sharma , Dhiren Kumar Basnet

In this note, we define and investigate ideal covering numbers of associative rings (not assumed to be commutative or unital): three invariants defined as the minimal number of proper left, right, or two-sided ideals whose union equals the…

Rings and Algebras · Mathematics 2025-08-15 Malcolm Hoong Wai Chen