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Consider a reductive linear algebraic group $G$ acting linearly on a polynomial ring $S$ over an infinite field; key examples are the general linear group, the symplectic group, the orthogonal group, and the special linear group, with the…

Commutative Algebra · Mathematics 2023-07-11 Melvin Hochster , Jack Jeffries , Vaibhav Pandey , Anurag K. Singh

We show that the formal skew Laurent series ring $R = D(\! ( x; \sigma )\! )$ over a commutative Dedekind domain $D$ with an automorphism $\sigma$ is a noncommutative Dedekind domain. If $\sigma$ acts trivially on the ideal class group of…

Rings and Algebras · Mathematics 2025-10-10 Daniel Vitas

It is proved that an element $r$ in the center of a coherent ring $\Lambda$ annihilates $\mathrm{Ext}^{n}_{\Lambda}(M,N)$, for some positive integer $n$ and all finitely presented $\Lambda$-modules $M$ and $N$, if and only if the bounded…

Representation Theory · Mathematics 2014-08-22 Srikanth B. Iyengar , Ryo Takahashi

In this paper, we prove that if a compact K\"ahler manifold $X$ has a smooth Hermitian metric $\omega$ such that $(T_X,\omega)$ is uniformly RC-positive, then $X$ is projective and rationally connected. Conversely, we show that, if a…

Algebraic Geometry · Mathematics 2020-11-18 Xiaokui Yang

We prove the following;Theorem:Let R be a prime noetherian ring with k.dimR = n, n a finite non-negative integer. We refer the reader to the definitions (1.1) of this paper.For a fixed non-negative integer m, m<n let Xm be the full set of…

Rings and Algebras · Mathematics 2023-08-21 C. L. Wangneo

Let $\xx= x_1,\ldots,x_r$ denote a system of elements of a commutative ring $R$. For an $R$-module $M$ we investigate when $\xx$ is $M$-pro-regular resp. $M$-weakly pro-regular as generalizations of $M$-regular sequences. This is done in…

Commutative Algebra · Mathematics 2024-04-23 Peter Schenzel

Let $R$ be a commutative ring of dimension $d$, $S = R[X]$ or $R[X, 1/X]$ and $P$ a finitely generated projective $S$ module of rank $r$. Then $P$ is cancellative if $P$ has a unimodular element and $r \geq d + 1$. Moreover if $r \geq \dim…

K-Theory and Homology · Mathematics 2015-12-01 Anjan Gupta

Let S be a commutative ring with topologically noetherian spectrum and let R be the absolutely flat approximation of S. We prove that subsets of the spectrum of R parametrise the localising subcategories of D(R). Moreover, we prove the…

Commutative Algebra · Mathematics 2012-10-02 Greg Stevenson

Given a group G acting on a ring R, one can construct the skew group ring R*G. Skew group rings have been studied in depth, but necessary and sufficient conditions for the simplicity of a general skew group ring are not known. In this…

Rings and Algebras · Mathematics 2007-05-23 Kathi Crow

Let R be a commutative noetherian local ring. A finitely generated R-module C is semidualizing if it is self-orthogonal and satisfies the condition Hom_R(C,C) \cong R. We prove that a Cohen-Macaulay ring R with dualizing module D admits a…

Commutative Algebra · Mathematics 2009-11-23 David A. Jorgensen , Graham J. Leuschke , Sean Sather-Wagstaff

In this article, we consider a twisted partial action $\alpha$ of a group $G$ on a ring $R$ and it is associated partial crossed product $R*_{\alpha}^wG$. We study necessary and sufficient conditions for the commutativity and simplicity of…

Rings and Algebras · Mathematics 2013-06-25 Alexandre Baraviera , Wagner Cortes , Marlon Soares

Let R be a ring (not necessarily commutative). A left R-module is said to be cotorsion if Ext 1 R (G, M) = 0 for any flat R-module G. It is well known that each pure-injective left R-module is cotorsion, but the converse does not hold: for…

Rings and Algebras · Mathematics 2016-03-25 Francois Couchot

Let $D$ be a finite-dimensional division algebra over its center and $R=D[t;\sigma,\delta]$ a skew polynomial ring. Under certain assumptions on $\delta$ and $\sigma$, the ring of central quotients $D(t;\sigma,\delta) = \{f/g \,|\, f \in…

Rings and Algebras · Mathematics 2020-06-19 Susanne Pumpluen , Daniel Thompson

Let $R$ be a lattice ordered ring along with a truncation in the sense of Ball. We give a necessary and sufficient condition on $R$ for its unitization $R\oplus\mathbb{Q}$ to be again a lattice ordered ring. Also, we shall see that…

Commutative Algebra · Mathematics 2019-10-28 Karim Boulabiar , Mounir Mahfoudhi

We show that a ring R has stable range one if and only if every left unit lifts modulo every left principal ideal. We also show that a left quasi-morphic ring has stable range one if and only if it is left uniquely generated. Thus we answer…

Rings and Algebras · Mathematics 2026-01-08 Feroz Siddique

It is proved that, for a pre-ordered vector space $X$, the quotient space $(X/A,[W])$ is an Archimedeanization of $X$, where $W$ is the closure of the positive wedge $X_+$ in ru-topology, $A=W\cap(-W)$, and $[W]$ is the quotient set of $W$…

Functional Analysis · Mathematics 2026-05-22 Eduard Emelyanov

In this paper, we introduce the upper and lower approximations on the invers set-valued mapping and the approximations an established on a powerful set valued homomorphism from a ring R1 to power sets of a ring R2. Moreover, the properties…

General Mathematics · Mathematics 2020-12-01 Faraj. A. Abdunabi , Ahmed Shletie

In 2011, Khurana, Lam and Wang define the following property. (*)A commutative unital ring A satisfies the property ''power stable range one'' if for all a, b $\in$ A with aA + bA = A there are an integer N = N (a, b) $\ge$ 1 and $\lambda$…

Commutative Algebra · Mathematics 2020-10-13 J. Fresnel , Michel Matignon

We investigate whether an arbitrary non-zero $\mathbb{E}_\infty$-ring $A$ admits a reduced point, meaning an $\mathbb{E}_\infty$-map $A\to T$ such that $\pi_{\ast}T$ is a graded field. We show that if $2\in \pi_0A$ is not invertible, then…

Algebraic Topology · Mathematics 2025-08-19 Florian Riedel

In this paper, we study the properties of noetherian rings with uniform annihilators. It turns out that all these rings should be universally catenary and locally equidimensional. We will give a necessary and sufficient condition for these…

Commutative Algebra · Mathematics 2007-05-23 Caijun Zhou