关于伪投射模的若干讨论

给出了伪投射模的另外一种等价定义,并对伪投射模的自同态环的Jacobson根做了讨论,还对伪投射盖做了某些探讨.     

投射根和亚投射模

本文研究了投射根和亚投射模的性质.利用Noether环、Noether模的性质给出了亚投射模、投射根是投射的条件,环的投射根为零、幂等的条件.最后,给出了一些例子.本文的大部分结果是陈焕艮等人的一系列主要结果的推广.     

关于伪投射模（英）

本文的主要目的是给出投射模的一个特征性质，从而说明1984年A.K.Tiwary等人关于伪投射模的一个结果是不成立的.此外，本文给出了投射模、半单模以及伪投射模之间的一些关系，并用伪投射模给出了半单环的一个特征性质.     

半∑准投射模自同态环的稳定秩

本文证明了若半Σ准投射模是弱n满投射的,则其自同态环的稳定秩至多为n,从而部分推广了文献[3]的—个主要结果.     

关于形式三角矩阵环

本文研究形式三角矩阵环R的若干新性质,讨论R-模的伪投射性,给出了形式三角矩阵环R是V-环或半V-环的充要条件.同时,给出了R是PS-环的条件.     

关于形式三角矩阵环

本文研究形式三角矩阵环 R 的若干新性质,讨论 R-模的伪投射性,给出了形式三角矩阵环 R 是 V-环或半 V-环的充要条件．同时,给出了 R 是 PS-环的条件．     

T投射模与G半单环

本文研究 T 投射模与 T 投射覆盖,刻划了 G 半单环类,并推广了一般投射覆盖的一些结论.     

弱直投射模和弱直内射模

引入了弱直投射和弱直内射模的概念，给出了它们的一些性质。使用弱直投射和弱直内射模刻划了遗传环、半遗传环、半单环和ＱＦ－环。     

局部几乎完全整环的几点注记

整环$R$被称为局部几乎完全整环, 指的是对任意极大理想${\frak m}$都有$R_{{\frak m}}$是几乎完全整环. 本文利用局部完全环, 几乎投射模, 弱内射模, 几乎强平坦模和强Matlis余挠模给出了局部几乎完全整环的若干等价刻画.     

投射模的局部化特征

本文给出了对任何Ｐ，Ｑ∈Ｐ（Ｒ），Ｐｑ≌Ｑｑ，Ｖｑ∈ＳｐｅｃＲ当且发Ｐ≌Ｑ的充要条件，研究了半局部环，零维环等常见及其多项式环，幂级数环上投射模的局部化特征。     

Gorenstein projective dimensions of complexes

We show that over a right coherent left perfect ring R, a complex C of left R-modules is Gorenstein projective if and only if C ^m is Gorenstein projective in R-Mod for all m ∈ ℤ. Basing on this we show that if R is a right coherent left perfect ring then Gpd(C) = sup{Gpd(C ^m )|m ∈ ℤ} where Gpd(−) denotes Gorenstein projective dimension.     

C-Pure Projective Modules

This paper investigates the structure of cyclically pure (or C-pure) projective modules. In particular, it is shown that a ring R is left Noetherian if and only if every C-pure projective left R-module is pure projective. Also, over a left hereditary Noetherian ring R, a left R-module M is C-pure projective if and only if M = N ⊕ P, where N is a direct sum of cyclic modules and P is a projective left R-module. The relationship C-purity with purity and RD-purity are also studied. It is shown that if R is a local duo-ring, then the C-pure projective left R-modules and the pure projective left R-modules coincide if and only if R is a principal ideal ring. If R is a left perfect duo-ring, then the C-pure projective left R-modules and the pure projective left R-modules coincide if and only if R is left Köthe (i.e., every left R-module is a direct sum of cyclic modules). Also, it is shown that for a ring R, if every C-pure projective left R-module is RD-projective, then R is left Noetherian, every p-injective left R-module is injective and every p-flat right R-module is flat. Finally, it is shown that if R is a left p.p-ring and every C-pure projective left R-module is RD-projective, then R is left Noetherian hereditary. The converse is also true when R is commutative, but it does not hold in the noncommutative case.     

关于R—投射模是投射模的环

本文研究了所有Ｒ—投射模都是投射模的环（ＲＰ—环），得出了它的几个等价条件，证明了：Ｓ＝Ｒｎ为ＲＰ—环当且仅当Ｒ为ＲＰ—环；∑ｎｉ＝１Ｒｉ为ＲＰ—环当且仅当每个Ｒｉ为ＲＰ—环．讨论了ＲＰ—环的左投射维数．     

关于Gorenstein投射维数的一个注记

本文研究了Gorenstein投射维数的相关问题.利用经典同调维数的研究方法,给出了Gorenstein投射维数有限模的Gorenstein投射维数的一个刻画,并利用这一结果证明了Gorenstein完全环和Artin环的Gorenstein整体维数分别由各自的循环模和单模的Gorenstein投射维数来确定.这些结论丰富了Gorenstein同调代数理论.     

关于左完全幺半群

设Ｓ是左完全幺半群．本文讨论了左，右Ｓ－系的链条件，特别地证明了右Ｓ－系的Ｂｊｏｒｋ定理．     

On FC-Purity and I-Purity of Modules and Köthe Rings

In this article, several characterizations of certain classes of rings via FC-purity and I-purity are considered. Among others results, it is shown that every I-pure injective left R-module is projective if and only if every FC-pure projective left R-module is injective, if and only if, R is a semisimple ring. In particular, the structures of FC-pure projective and I-pure projective modules over a left Artinian ring are completely described. Also, it is shown that every left R-module is FC-pure projective if and only if every indecomposable left R-module is a finitely presented cyclic R-module, if and only if, R is a left Köthe ring. Finally, we introduce FC-pure flatness and I-pure flatness of modules and several characterizations of these notions are given. In particular, we show that a commutative ring R is quasi-Frobenius if and only if R is an Artinian ring and I-pure injective, if and only if, R is an Artinian ring and the injective envelope E(R) is an FC-pure projective R-module.     

Gorenstein Modules and Dualizing Modules

In this article, we study the characterizations of Gorenstein injective left S-modules and finitely generated Gorenstein projective left R-modules when there is a dualizing S-R-bimodule associated with a right noetherian ring R and a left noetherian ring S.     

Pseudocomplex and Pseudo(bi)quaternion Mappings

A problem posed by V. I. Arnold is solved by describing all homeomorphisms of an affine quaternion space that take any left or right affine quaternion line to a left or right affine quaternion line (a left line can be taken to a right one, and vice versa).     

Perfect Rings: A Local Approach

We analyze how the left perfect condition on a ring A (not necessarily with identity) relates to the left perfect condition on unital subrings of the form eAe (where e is idempotent). We then use this analysis to examine a class of graded left perfect rings.     

On Artiness of Right CF Rings

Abstract

Let R be a ring. We prove that every right CF ring is right artinian under the left perfect or strongly right C2 condition. We also show that a right noetherian, left P-injective, left CS-ring is QF.