关于J.Vukman的一个问题

关于Ｊ．Ｖｕｋｍａｎ的一个问题黄允宝（杭州教育学院）本文Ｒ始终表示一个中心为Ｃ的结合环，我们将用符号［ｘ，ｙ］表示ｘｙ－ｙｘ并使用恒等式［ｘｙ，ｚ］＝［ｘ，ｚ］ｙ＋ｘ［ｙ，ｚ］，［ｘ，ｙｚ］＝［ｘ，ｙ］ｚ＋ｙ［ｘ，ｚ］．称环Ｒ是素环如果ａＲｂ＝０蕴含...     

强正则环的刻划

强正则环的刻划胡卫群（安徽省滁州师范专科学校）Ａｕｓｌａｎｄｅｒ在［３］中证明了：环Ａ是ＶｏｎＮｅｕｍａｎｎ正则的对于Ａ的任意左理想Ｌ与Ａ的任意右理想Ｒ，，总有ＲｎＬ＝ＲＬ．Ｒ．ＹｕｅＣｈｉＭｉｎｇ在［２］中推广了Ａｕｓｌａｎｄｅｒ［３］的结果，证明...     

交换半群环的分式环

设含幺交换环Ｒ对其乘法子集Ｔ的分式环为ＲＴ，交换幺半群Ｓ在其子半群∑处局部化为Ｓ∑本文证明了Ｒ［Ｓ］对于Ａ的分环式环Ｒ［Ｓ］ＡＭ 构于半群环ＲＴ［Ｓ∑］。     

关于文“具有两个代数曲线解的三次系统的代数极限环”的注记

本文弥补了文［４］中主要定理的不足之处,并且推广了文［５］的结果     

含有零化子为零的f—元的l—环

Ｓｔｕａｒｔ Ａ．Ｓｔｅｉｎｂｅｒｇ在［１］，［２］，［３］中讨论了具有左ｆ－超单位的ｌ－环的一些性质。本文将这些结论推广到含有零化子为零的ｆ－元的ｌ－环。     

关于文“具有两个代数曲线解的 三次系统的代数极限环”的注记

本文弥补了文［4］中主要定理的不足之处,并且推广了文［5］的结果.     

广义幂级数环的PP性质

作为幂级数环的推广,Ｒｉｂｅｎｂｏｉｍ引入了广义幂级数环的概念．设Ｒ是有单位元的交换环,（Ｊ,≤）是严格全序半群．本文中我们证明了如下结果：（１）广义幂级数环 ［［Ｒｓ］］是ＰＰ－环当且仅当Ｒ是ＰＰ－环且Ｂ（Ｒ）的任意 Ｓ－可标子集Ｃ在Ｂ（Ｒ）中有最小上界;（２）如果对任意ｓ∈Ｓ都有０≤ｓ,则［［Ｒｓ,≤］］是弱ＰＰ－环当且仅当Ｒ是弱ＰＰ－环．我们还给出了一个例子说明交换的弱ＰＰ－环可以不是ＰＰ－环．     

关于二维合作自治系统的闭轨线

本文主要研究二维合作自治系统的闭轨线，推广了［１］的结果，得到了定理１于定理５。为简便计，本文采用［１］的术语，而未说明的概念或符号引自［２］。     

无穷远分界线的稳定性和产生极限环的条件

本文给出了无穷远分界线稳定性的判据以及从无穷远分界线产生极限环的条件，其结果包括了［７］，［８］的主要结果。     

模的嵌入问题

本文首先在文［１］工作的基础上进一步讨论了“每个有限生成模可嵌入到自由模”的环类，这类环称为ＦＧＦ－环，接着引进了一类包括ＦＧＦ－环和拟完全环的环类，这类环称作ＦＧＦＦ－环，即“每个有限生成平坦模可嵌入到自由模中”，讨论了这类环的一些特征性质及其与已知一些重要环类间的关系．这一类环的背景是文［１－６］．本文还回答了文［５］的一个问题．     

Some minimal rings related to 2-primal rings

In a paper on the taxonomy of 2-primal rings, examples of various types of rings that are related to commutativity such as reduced, symmetric, duo, reversible and PS I were given in order to show that the ring class inclusions were strict. Many of the rings given in the examples were infinite. In this paper, where possible, examples of minimal finite rings of the various types are given. Along with the rings in the previous taxonomy, NI, abelian and reflexive rings are also included.     

Commutative neat group rings

A ring R is called clean if every element of it is a sum of an idempotent and a unit. A ring R is neat if every proper homomorphic image of R is clean. When R is a field, then a complete characterization has been obtained for a commutative group ring RG to be neat, but not clean. And if R is not a field, then necessary conditions are obtained for a commutative group ring RG to be neat, but not clean. A counterexample is given to show that these necessary conditions are not sufficient.     

Minimal reversible nonsymmetric rings

Marks showed that ${\mathbb{F}}_2{Q}_8$, the ${\mathbb{F}}_2$ group algebra over the quaternion group, is a reversible nonsymmetric ring, then questioned whether or not this ring is minimal with respect to cardinality. In this work, it is shown that the cardinality of a minimal reversible nonsymmetric ring is indeed 256. Furthermore, it is shown that although ${\mathbb{F}}_2{Q}_8$ is a duo ring, there are also examples of minimal reversible nonsymmetric rings which are nonduo.     

McCoy Rings Relative to a Monoid

For a monoid M, we introduce M-McCoy rings, which are a generalization of McCoy rings and M-Armendariz rings; and investigate their properties. We first show that all reversible rings are right M-McCoy, where M is a u.p.-monoid. We also show that all right duo rings are right M-McCoy, where M is a strictly totally ordered monoid. Then we show that semicommutative rings and 2-primal rings do have a property close to the M-McCoy condition. Moreover, it is shown that a finitely generated Abelian group G is torsion free if and only if there exists a ring R such that R is G-McCoy. Consequently, several known results on right McCoy rings are extended to a general setting.     

Characterizations of QF Rings

A ring R is called “left GP-injective” if for any 0 ≠ a ∈ R, there exists n > 0 such that a ⁿ  ≠ 0 and a ⁿ R = r(l(a ⁿ )). It is proved that (1) every right Noetherian left GP-injective ring such that every complement left ideal is a left annihilator is a QF ring, (2) every left GP-injective ring with ACC on left annihilators such that every complement left ideal is a left annihilator is a QF ring, and (3) every left P-injective left CS ring satisfying ACC on essential right ideals is a QF ring. Several well-known results on QF rings are obtained as corollaries.     

Some Characterizations of VNL Rings

A ring R is said to be von Newmann local (VNL) if for any a ∈ R, either a or 1 ?a is (von Neumann) regular. The class of VNL rings lies properly between exchange rings and (von Neumann) regular rings. We characterize abelian VNL rings. We also characterize and classify arbitrary VNL rings without an infinite set of orthogonal idempotents; and also the VNL rings having a primitive idempotent e such that eRe is not a division ring. We prove that a semiperfect ring R is VNL if and only if for any right uni-modular row (a ₁, a ₂) ∈ R ², one of the a _i 's is regular in R. Formal triangular matrix rings that are VNL are also characterized. As a corollary, it is shown that an upper triangular matrix ring T _n (R) is VNL if and only if n = 2 or 3 and R is a division ring.     

具有性质（P）的环的同调维数

主要研究具有性质（P）环的同调维数,所得的结果推广了[1]的结果。     

Semiclean Rings

Abstract

The notion of semiclean elements in a ring is defined. Every clean element is semiclean. A ring R is said to be semiclean if every element in R is semiclean. The group ring Z _p G with G a cyclic group of order 3 is proved to be semiclean. The n × n matrix ring M _n (R) over a semiclean ring is semiclean. If R is a torsion free semiclean ring in which every element of R can be written as a sum of periodic and ±1, then R is clean. Every element in a semiclean ring R with 2 invertible is a sum of no more than 3 units.     

Polynomial extensions of quasi-Baer rings

Summary For a ring endomorphism &agr; and an &agr;-derivation &dgr;, we introduce &agr;-compatible rings which are a generalization of &agr;-rigid rings, and study on the relationship between the quasi Baerness and p.q.-Baer property of a ring R and those of the polynomial extensions (including formal skew power series, skew Laurent polynomials and skew Laurent series). As a consequence we obtain a generalization of [6], [8] and [16].     

New Characterizations of Quasi-Frobenius Rings

In this article, we give several new characterizations of Quasi-Frobenius rings by using mininjectivity, simple injectivity, and small injectivity, respectively. Several known results on Quasi-Frobenius rings are reproved as corollaries.