右IF－环及凝聚环的挠理论

本文研究了右ＩＦ－环的性质，证明出环Ｒ是右ＩＦ－环当且仅当Ｒ是左凝聚环，并且是平坦模；由此证明出右ＩＦ－环与左ＧＱＦ－环是等价的，其次应用右ＩＦ－环研究了凝聚环的挠理论性质，证明出凝聚环与Ｔ－凝聚环的关系。     

凝聚环和IF环

本文利用特征模，Ｎ０－内射维数对凝聚环给出了一些新的刻划．得到了凝聚环与ＩＦ环的一些有意义的性质．推广了引文［１］中的两个主要定理之一的定理２的结论．     

环的左（N，U）－凝聚维数

设R和S是环，U是平坦右R-模，V是平坦右S-模．本中我们证明了(N，(U，V))-lc．dim(R S)=sup((N，U)-lc．dimR，(N，V)-lc．dimS)．     

凝聚环上的Cotilting模

本文首先介绍了ｃｏ－＊－模的概念和刻划了凝聚环的一些性质，然后刻划了凝聚环上的ｃｏｔｉｌｔｉｎｇ模。     

FP—内射环和IF环的几个特征

本文给出了FP—内射环和IF环的如下几个特征:(l)R为右FP—内射环当且仅当任意左R—模正合列Kⁿ→Kⁿ→N→0 N为无挠模,当且仅当任一n阶矩阵环为右P—内射环;(2)R为左IF环当且仅当任一有限生成左R—模均可嵌入平坦模;(3)R为IF环当且仅当R为伪凝聚的上平坦环。     

有限表现维数与凝聚环

在本文中,我们从研究投射等价模的有限表现维数的关系入手,给出了有限表现维数的维数转移定理(定理2.5),并且运用有限表现维数刻划了凝聚环(定理2.4)。最后我们得到了在经典局部化下,环与模的有限表现维数的不变性定理(定理2.6,定理2.8)。     

环的左(N,U)-凝聚维数

设R和S是环,U是平坦右R-模,V是平坦右S-模.本文中我们证明了(N,(U,V))-lc.dim(R⊕S)=sup((N,U)-lc.dim R,(N,V)-lc.dimS).     

无挠左（右）Artin环是拟Frobenius环

无挠左（右）Ａｒｔｉｎ环是拟Ｆｒｏｂｅｎｉｕｓ环乌成伟（吉林工学院基础部，长春１３００１２）关键词内积，左（右）内零化子，自内射环．分类号ＡＭＳ（１９９１）１６Ｄ５０／ＣＣＬＯ１５３．３设Ｒ为有１的左（右）Ａｒｔｉｎ环，如果对于任一整数洲与ｒ∈Ｒ，ｍ...     

п—凝聚环中的对偶性

通过π-凝聚环上的f.g.模的自反性引进了WQF-环和GIF-环,给出了QF-环-个新的刻画,并研究了π-凝聚环上的W∧n模上的自反性的特征性质。     

IF环和拟ZIF环

本文定义了拟ＺＩＦ环．研究了ＩＦ环与拟ＺＩＦ环的结构．进一步地，讨论了ＩＦ环与拟ＺＩＦ环的关系，并用拟ＺＩＦ环刻划了ＩＦ环．     

Lifting Modules Over Right Perfect Rings

A module M is called extending if, for any submodule X of M, there exists a direct summand of M which contains X as an essential submodule, that is, for any submodule X of M, there exists a closure of X in M which is a direct summand of M. Dually, a module M is said to be lifting if, for any submodule X of M, there exists a direct summand of M which is a co-essential submodule of X, that is, for any submodule X of M, there exists a co-closure of X in M which is a direct summand of M.

Okado (1984 Okado , M. ( 1984 ). On the decomposition of extending modules . Math. Japonica 29 : 939 – 941 . [Google Scholar]) has studied the decomposition of extending modules over right noetherian rings. He obtained the following: A ring R is right noetherian if and only if every extending R-module can be expressed as a direct sum of indecomposable (uniform) modules.

In this article, we show that every (finitely generated) lifting module over a right perfect (semiperfect) ring can be expressed as a direct sum of indecomposable modules. And we consider some application of this result.     

半局部环的von Neumann正则性

主要借助small-内射模(环),给出半局部环的正则性和强正则性的一些等价刻画.     

Soc-Injective Rings and Modules*

If M and N are right R-modules, M is called Socle-N-injective (Soc-N-injective) if every R-homomorphism from the socle of N into M extends to N. Equivalently, for every semisimple submodule K of N, any R-homomorphism f : K → M extends to N. In this article, we investigate the notion of soc-injectivity.     

Weakly $I$-Semiregular Rings and $I$-Semiregular Rings

Let $I$ be an ideal of a ring $R$. We call $R$ weakly $I$-semiregular if $R$/$I$ is a von Neumann regular ring. This definition generalizes $I$-semiregular rings. We give a series of characterizations and properties of this class of rings. Moreover, we also give some properties of $I$-semiregular rings.     

Finitely Generated Flat Modules and a Characterization of Semiperfect Rings

Abstract

For a ring S, let K ₀(FGFl(S)) and K ₀(FGPr(S)) denote the Grothendieck groups of the category of all finitely generated flat S-modules and the category of all finitely generated projective S-modules respectively. We prove that a semilocal ring Ris semiperfect if and only if the group homomorphism K ₀(FGFl(R)) → K ₀(FGFl(R/J(R))) is an epimorphism and K ₀(FGFl(R)) = K ₀(FGPr(R)).     

关于$\pi$-半交换环

A ring R is said to be π-semicommutative if a, b ∈ R satisfy ab = 0 then there exists a positive integer n such that anRbn= 0. We study the properties of π-semicommutative rings and the relationship between such rings and other related rings. In particular, we answer a question on left GWZI rings negatively.