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Let $R$ be a semilocal principal ideal domain. Two algebraic objects over $R$ in which scalar extension makes sense (e.g. quadratic spaces) are said to be of the same genus if they become isomorphic after extending scalars to all…

Rings and Algebras · Mathematics 2016-01-12 Eva Bayer-Fluckiger , Uriya A. First

A group, $\fl{H}$, of automorphisms of a totally disconnected locally compact group, $G$, is flat if there is a compact open $U\leq G$ such that the index $[\alpha(U):U\cap \alpha(U)]$ is mininimized for every $\alpha\in\fl{H}$. The…

Group Theory · Mathematics 2025-12-12 George A. Willis

In this note, we investigate the Baer splitting problem over commutative rings. In particular, we show that if a commutative ring $R$ is $\tau_q$-semisimple, then every Baer $R$-module is projective.

Commutative Algebra · Mathematics 2025-09-05 Xiaolei Zhang , Hwankoo Kim

Suppose that $G$ is a finite group and $k$ is a field of characteristic $p >0$. Let $\mathcal{M}$ be the thick tensor ideal of finitely generated modules whose support variety is in a fixed subvariety $V$ of the projectivized prime ideal…

Representation Theory · Mathematics 2022-10-05 Jon F. Carlson

Let $G$ be a subgroup of the automorphism group of a commutative ring with identity $T$. Let $R$ be a subring of $T$ such that $R$ is invariant under the action by $G$. We show $R^G\subset T^G$ is a minimal ring extension whenever $R\subset…

Commutative Algebra · Mathematics 2014-05-08 Amy Schmidt

This survey provides a comprehensive overview of the recent advancements in the theory of ``uniformly $S$''-algebraic structures in commutative ring theory. Originating from the classical concepts of Noetherian, coherent, von Neumann…

Commutative Algebra · Mathematics 2026-02-17 Xiaolei Zhang , Wei Qi

Let k be an algebraically closed field of characteristic 2, and let W be the ring of infinite Witt vectors over k. Suppose G is a finite group and B is a block of kG with a dihedral defect group D such that there are precisely two…

Group Theory · Mathematics 2011-09-13 Frauke M. Bleher , Giovanna Llosent , Jennifer B. Schaefer

In this paper, we characterize several properties of commutative notherian local rings in terms of the left perpendicular category of the category of finitely generated modules of finite projective dimension. As an application we prove that…

Commutative Algebra · Mathematics 2011-04-25 Tokuji Araya , Kei-ichiro Iima , Ryo Takahashi

We explain a derived version of the basic construction of localisations of module categories by means of idempotent ideals, which lie at the heart of Faltings' almost ring theory. We use it to provide an example of a commutative algebra in…

Commutative Algebra · Mathematics 2025-10-28 Fabian Hebestreit , Peter Scholze

We prove conditions ensuring that a Lie ideal or an invariant additive subgroup in a ring contains all additive commutators. A crucial assumption is that the subgroup is fully noncentral, that is, its image in every quotient is noncentral.…

Rings and Algebras · Mathematics 2025-03-04 Eusebio Gardella , Tsiu-Kwen Lee , Hannes Thiel

For a given class of modules $\mathcal{A}$, we denote by $\widetilde{\mathcal{A}}$ the class of exact complexes $X$ having all cycles in $\mathcal{A}$, and by $dw(\mathcal{A})$ the class of complexes $Y$ with all components $Y_j$ in…

Rings and Algebras · Mathematics 2020-01-22 Sergio Estrada , Alina Iacob , Holly Zolt

$(1)$ Let $M\subset N$ be a commutative cancellative torsion-free and subintegral extension of monoids. Then we prove that in the case of ring extension $A[M]\subset A[N]$, the two notions, subintegral and weakly subintegral coincide…

Commutative Algebra · Mathematics 2025-07-21 Md Abu Raihan , Leslie G. Roberts , Husney Parvez Sarwar

There are several theorems describing the intricate relationship between flatness and associated primes over commutative Noetherian rings. However, associated primes are known to act badly over non-Noetherian rings, so one needs a suitable…

Commutative Algebra · Mathematics 2015-12-11 Neil Epstein , Jay Shapiro

A full subcategory of modules over a commutative ring $R$ is wide if it is abelian and closed under extensions. Hovey \cite{wide} gave a classification of wide subcategories of finitely presented modules over regular coherent rings in terms…

K-Theory and Homology · Mathematics 2009-12-03 Sunil K. Chebolu

The purpose of this paper is to give a partial positive answer to a question raised by Khurana et al. as to whether a ring $R$ with stable range one and central units is commutative. We show that this is the case under any of the following…

Rings and Algebras · Mathematics 2019-10-11 Paula A. A. B. Carvalho , Christian Lomp , Jerzy Matczuk

Let R be a ring and X = SH(R)-{0} be the set of all non-zero strongly hollow ideals (briefly, sh-ideals) of R. We first study the concept SH-topology and investigate some of the basic properties of a topological space with this topology. It…

General Topology · Mathematics 2023-09-20 Sayed Malek Javdannezhad , Nasrin Shirali

Let $A$ be a finite dimensional associative $\mathbb{K}$-algebra over an algebraically closed field $\mathbb{K}$ of characteristic zero. To $A$, we can associate its basic form that is given by a quiver $Q = (Q_0, Q_1)$ with an admissible…

Representation Theory · Mathematics 2023-06-16 Charles Paquette , Deepanshu Prasad , David Wehlau

In this paper, we study the classes of rings in which every proper (regular) ideal can be factored as an invertible ideal times a nonempty product of proper radical ideals. More precisely, we investigate the stability of these properties…

Commutative Algebra · Mathematics 2020-09-15 Malik Tusif Ahmed , Najib Mahdou , Youssef Zahir

We examine the power series ring $R[[X]]$ over a valuation ring $R$ of rank 1, with proper, dense value group. We give a counterexample to Hilbert's syzygy theorem for $R[[X]]$, i.e. an $R[[X]]$-module $C$ that is flat over $R$ and has flat…

Commutative Algebra · Mathematics 2025-10-03 Adam Jones

In this paper we consider reduced (non-normal) commutative noetherian rings $R$. With the help of conductor ideals and trace ideals of certain $R$-modules we deduce a criterion for a reflexive $R$-module to be closed under multiplication…

Commutative Algebra · Mathematics 2019-11-27 Eleonore Faber