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。     

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．     

环与剩余类环的同调维数

Ｓａｎｄｏｍｉｅｒｓｋｉ Ｆ．Ｌ,Ｓｍａｌｌ Ｌ．Ｗ,和 Ｆｉｅｌｄｓ Ｋ．Ｌ．［１－２］在“幂零”条件下研究了环与约化环的同调维数．然而对一些环（如交换 Ｖｏｎ Ｎｅｕｍａｎｎ正则环）,“幂零’的条件是不成立的．因此,在本文中我们考虑非“幂零”条件下（如Ｒ（Ｒ／Ｉ）（（Ｒ／Ｉ）Ｒ）是Ｒ－投身的或Ｒ（Ｒ／Ｉ）Ｒ是Ｒ－平坦的）,环与约化环的同调维数．     

拟环为拟除环的几个条件

我们定义了左、右不变拟了环和完全亚直既约拟环，给出了拟环为拟除环的几个条件．这些结果可以直接推广到结合环．     

关于NF-环的构造

研究了无限的ＮＦ－环及有限的ＮＦ－环，并且给出了有限ＮＦ－环的构造．     

特征模对环的刻划

设Ｒ是一个环，Ｍ是一个左Ｒ摸，Ｍ＊＝ＨｏｍＺ（Ｍ，Ｑ／Ｚ）为Ｍ的特征模．Ｒ．Ｒ．Ｃｏｌｂｙ和Ｔ．Ｊ．Ｃｈｏａｔｈａｎ等人利用特征模对ＩＦ环、凝聚环、Ｎｏｅｔｈｅｒ环、Ａｒｔｉｎ环作出了一些非常好的刻划．本文利用特征模对更为广泛的一些环作出了较有意义的刻划．     

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．     

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...     

REMARKS ON QUASI-PERFECT RINGS AND FC-RINGS

设Ｒ是有单位元的环，Ｓ是Ｒ的几乎优越扩张，Ｇ是有限群且｜Ｇ｜－１∈Ｒ．证明了Ｒ是ＦＣ－环（拟完备环，凝聚环）当且仅当Ｓ是ＦＣ－环（拟完备环，凝聚环），也当且仅当Ｓｍａｃｈ积Ｒ＃Ｇ＊是ＦＣ－环（拟完备环，凝聚环）．     

J-clean环的推广

如果R中每个元素(对应地,可逆元)均可表示为一个幂等元与环R的Jacobson根中一个元素之和,则称环R是J-clean环(对应地,UJ环).所有的J-clean环都是UJ环.作为UJ环的真推广,本文引入GUJ环的概念,研究GUJ环的基本性质和应用.进一步地,研究每个元素均可表示为一个幂等元与一个方幂属于环的Jacobson根的元素之和的环.     

Modules Whose Endomorphism Rings are Division Rings

The well-known Schur's Lemma states that the endomorphism ring of a simple module is a division ring. But the converse is not true in general. In this paper we study modules whose endomorphism rings are division rings. We first reduce our consideration to the case of faithful modules with this property. Using the existence of such modules, we obtain results on a new notion which generalizes that of primitive rings. When R is a full or triangular matrix ring over a commutative ring, a structure theorem is proved for an R-module M such that End _R (M) is a division ring. A number of examples are given to illustrate our results and to motivate further study on this topic.     

有限扩张环

证明了环的有限扩张性可以传递到矩阵环上;通过PP环,半遗传环以及有限余非奇异环刻划了有限扩张环,并推广了文献[2]的定理2.1; 对于FGF与CF猜测,给出了部分肯定的回答,即右有限扩张右CF环是右CEP的,从而是右aritian的,改进了文献[6]的定理3.7.     

Ideal-Symmetric and Semiprime Rings

Lambek extended the usual commutative ideal theory to ideals in noncommutative rings, calling an ideal A of a ring R symmetric if rst ∈ A implies rts ∈ A for r, s, t ∈ R. R is usually called symmetric if 0 is a symmetric ideal. This naturally gives rise to extending the study of symmetric ring property to the lattice of ideals. In the process, we introduce the concept of an ideal-symmetric ring. We first characterize the class of ideal-symmetric rings and show that this ideal-symmetric property is Morita invariant. We provide a method of constructing an ideal-symmetric ring (but not semiprime) from any given semiprime ring, noting that semiprime rings are ideal-symmetric. We investigate the structure of minimal ideal-symmetric rings completely, finding two kinds of basic forms of finite ideal-symmetric rings. It is also shown that the ideal-symmetric property can go up to right quotient rings in relation with regular elements. The polynomial ring R[x] over an ideal-symmetric ring R need not be ideal-symmetric, but it is shown that the factor ring R[x]/xⁿR[x] is ideal-symmetric over a semiprime ring R.     

Ore Extensions of Skew Armendariz Rings

Let α be an endomorphism and δ an α-derivation of a ring R. We introduce the notion of skew-Armendariz rings which are a generalization of α-skew Armendariz rings and α-rigid rings and extend the classes of non reduced skew-Armendariz rings. Some properties of this generalization are established, and connections of properties of a skew-Armendariz ring R with those of the Ore extension R[x; α, δ] are investigated. As a consequence we extend and unify several known results related to Armendariz rings.     

The Rings Characterized by Minimal Left Ideals

We study these rings with every minimal left ideal being a projective, direct summand and a p-injective module, respectively. Some characterizations of these rings are given, and the relations among them are obtained. With these rings, we characterize seinisiinple rings. Finally, we introduce MC2 rings, and give some characterizations of MC2 rings.     

I半π正则环

Let R be a ring and I an ideal of R.A ring R is called I-semi-π-regular if R/I isπ-regular and idempotents of R can be strongly lifted modulo I.Charac- terizations of I-semi-π-regular rings are given and relations between semi-π-regular rings and semiregular rings are explored.     

Real Closed Valuation Rings

The real closed valuation rings, i.e., convex subrings of real closed fields, form a proper subclass of the class of real closed domains. It is shown how one can recognize whether a real closed domain is a valuation ring. This leads to a characterization of the totally ordered domains whose real closure is a valuation ring. Real closures of totally ordered factor rings of coordinate rings of real algebraic varieties are very frequently valuation rings. In particular, the real closure of the coordinate ring of a curve is an SV-ring (i.e., the factor rings modulo prime ideals are valuation rings). Real closed valuation rings play a role in the definition of real closed rings, as well as in the construction of real closures of rings and porings. They can also be used for the study of univariate differentiable semi-algebraic functions. This leads to the notion of differentiablility of semi-algebraic functions along half branches of curves.     

强symmetric环

为了统一交换环和约化环的层表示,Lambek引进了Symmetric环.继续symmetric环的研究,定义引入了强symmetric环的概念,研究它的一些扩张性质.证明环R是强symmetric环当且仅当R[x]是强symmetric环当且仅当R[x;x~(-1)]是强symmetric环.也证明对于右Ore环R的经典右商环Q,R是强symmetric环当且仅当Q是强symmetric环.