Generalization of Regular Modules

We study generalizations of regular modules by Ramamurthy and Mabuchi. These are also generalizations of fully right idempotent and fully left idempotent rings, respectively. We also define and study the properties of *-weakly regular modules, a generalization of fully idempotent rings.     

Abelian正则环的零因子图

We introduce the zero-divisor graph for an abelian regular ring and show that if R, S are abelian regular, then (K0(R),[R])≌(K0(S),[S])if and only if they have isomorphic reduced zero-divisor graphs. It is shown that the maximal right quotient ring of a potent semiprimitive normal ring is abelian regular,moreover,the zero-divisor graph of such a ring is studied.     

Abel正则球与完全正则半群

本文分别讨论了关于结合环和半群的二个定理，并且由结合环的这二个定理推出了如下准则：结合环Ｒ是Ａｂｅｌ正则的，当且仅当Ｒ的每个拟理想是正则环．     

Gorenstein正则环、奇点范畴和Ding模

本文证明了任意环的整体Ding投射维数和整体Ding内射维数一致,研究了奇点范畴和相对于Ding模的稳定范畴间的关系,并刻画了Gorenstein (正则)环以及环的整体维数的有限性.     

Flat Modules over Group Rings of Finite Groups

Let k be a commutative ring of coefficients and G be a finite group. Does there exist a flat k G-module which is projective as a k-module but not as a k G-module? We relate this question to the question of existence of a k-module which is flat and periodic but not projective. For either question to have a positive answer, it is at least necessary to have |k| ≥ ?_ω. There can be no such example if k is Noetherian of finite Krull dimension, or if k is perfect.     

Definability of Completely Decomposable Torsion-Free Abelian Groups by Groups of Homomorphisms

Let C be an Abelian group. An Abelian group A in some class of Abelian groups is said to be _C H-definable in the class if, for any group B\in , it follows from the existence of an isomorphism Hom(C,A) Hom(C,B) that there is an isomorphism A B. If every group in is _C H-definable in , then the class is called an _C H-class. In the paper, conditions are studied under which a class of completely decomposable torsion-free Abelian groups is a _C H-class, where C is a completely decomposable torsion-free Abelian group.     

正则WB-环

引进了WB-环,研究了正则环为WB-环的等价刻画．如果A是正则环R上的有限生成投射右模而且M_n(R)都是WB-环(n∈N),若B,C是任何右R-模而且A⊕B≌A⊕C,证明了存在正交理想I,J,使得B/BI■~⊕C/CI且C/CJ■~⊕B/BJ．这也给出了QB-环上新的模比较性质．     

Conjugacy Separability of Descending HNN-Extensions of Finitely Generated Abelian Groups

It is proved that an arbitrary descending HNN-extension of a finitely generated Abelian group is conjugacy separable.     

Finitely Generated Torsion-free Nilp otent Groups Admitting an Automorphism of Prime Order

Let G be a finitely generated torsion-free nilpotent group and α an automorphism of prime order p of G. If the map φ : G-→ G defined by gφ= [g, α]is surjective, then the nilpotent class of G is at most h(p), where h(p) is a function depending only on p. In particular, if α3= 1, then the nilpotent class of G is at most2.     

正则模与半单Artin环

本文用则模的术语给出了半单Artin 环的刻划。得到如下三个条件的等价性:(1)R 是一个半单Artin 环;(2)每一个R-模都是正则模;(3)每一个单纯R-模都是正则模。     

On Schurity of Finite Abelian Groups

A finite group G is called a Schur group, if any Schur ring over G is associated in a natural way with a subgroup of Sym(G) that contains all right translations. Recently, the authors have completely identified the cyclic Schur groups. In this article, it is shown that any abelian Schur group belongs to one of several explicitly given families only. In particular, any noncyclic abelian Schur group of odd order is isomorphic to ?₃ × ?_{3 ^k} or ?₃ × ?₃ × ? _p where k ≥ 1 and p is a prime. In addition, we prove that ?₂ × ?₂ × ? _p is a Schur group for every prime p.     

正则环与YJ-内射性

文献 [1]中 ,Ming.R.Y.C引进了 YJ 内射模的概念 ,且指出正则环上的每个模均是 YJ 内射模 ,那么反之如何呢 ?文 [1]中做了一些结果 ,本文拟就这个问题作进一步讨论 .     

关于正则模的自同态环

本文研究正则模Ｐ的自同态环Ｓ，主要给出使Ｓ的稳定秩为１的Ｐ的几个充分条件．     

Self-Small Abelian Groups as Modules over Their Endomorphism Rings

Abstract

The strongly essentially indecomposable self-small abelian groups, of finite torsion free rank, which are (almost-)projective as modules over their endomorphism rings are characterized.     

关于正则模的序

本文首次在模中引入序的概念，并就正则模给出序的一些性质．     

关于二次模的正交群

本文给出了交换环上二次模直交和的正交群的计算公式，对多项式环上的二次模，给出了一类子群的局部整体定理。     

群分次环与群分次模的基座

将关于交叉积的基座的主要结果推广到了群分次环上，得到了群分次环的基座的一些具体刻划，特别地，证明了对有限群G和强G－分次环R，有Soc(RR) Soc(ReRe)R soc^ ｜G｜（RR）。     

Feebly Baer Rings and Modules

A right module M over a ring R is called feebly Baer if, whenever xa = 0 with x ∈ M and a ∈ R, there exists e² = e ∈ R such that xe = 0 and ea = a. The ring R is called feebly Baer if R_R is a feebly Baer module. These notions are motivated by the commutative analog discussed in a recent paper by Knox, Levy, McGovern, and Shapiro [6 Knox , M. L. , Levy , R. , McGovern , W. Wm. , Shapiro , J. ( 2009 ) Generalizations of complemented rings with applications to rings of functions. . J. Alg. Appl. 8 ( 1 ): 17 – 40 .[Crossref] , [Google Scholar]]. Basic properties of feebly Baer rings and modules are proved, and their connections with von Neumann regular rings are addressed.     

Homomorphisms between A-Projective Abelian Groups and Left Kasch-Rings

Glaz and Wickless introduced the class G of mixed abelian groups A which have finite torsion-free rank and satisfy the following three properties: i) A _p is finite for all primes p, ii) A is isomorphic to a pure subgroup of _P A _P and iii) Hom(A, tA) is torsion. A ring R is a left Kasch ring if every proper right ideal of R has a non-zero left annihilator. We characterize the elements A of G such that E(A)/tE(A) is a left Kasch ring, and discuss related results.     

On Associative Ring Multiplication on Abelian Mixed Groups

An abelian group is called a mixed one if it is neither torsion nor torsion-free. It is to be proved that every mixed group can be provided with a nonzero associative ring structure. Our methods of proofs are straightforward and elementary.