交换环上上三角矩阵代数在全矩阵代数中的扩代数及其若当导子

设R是任意含么交换环,2是R的可逆元.M(n,R)表示R上所有n×n级矩阵形成的代数,T(n,R)表示R上所有n×n级上三角矩阵形成的代数.决定了T(n,R)在M(n,R)中的扩代数,并具体刻画了这些扩代数的若当导子.     

半素环上的微商

本文讨论了微商作用在半素环的某些左理想上的问题.给出了如下结果:设R是带有中心Z（R）的半素环.d和g是R的微商,L为R的非零左理想且r_R（L）=0.假设d（x）x-xg（x）∈Z（R）对任意的x∈L成立.那么d（R）?Z(R）且由d（R）生成的R的理想在R的中心里.     

A Note on the w-Global Transform of Mori Domains

Let R be a domain and let R wg be the w-global transform of R.In this note it is shown that if R is a Mori domain,then the t-dimension formula t- dim(R wg ) = t- dim(R) - 1 holds.     

关于半局部群环

Let R be an associative ring with identity.R is said to be semilocal if R/J(R)is(semisimple)Artinian,where J(R)denotes the Jacobson radical of R.In this paper,we give necessary and sufficient conditions for the group ring RG to be semilocal,where G is a locally finite nilpotent group.     

整环上二阶线性李代数的自同构

设Ｒ是有１的交换环，２是Ｒ的单位．本文决定了Ｒ上李代数ｓｌ２（Ｒ）的理想．进而，若Ｒ是整环，本文决定了ｓｌ２（Ｒ）与ｇｌ２（Ｒ）的自同构形式．     

A Note on the ω-Global Transform of Mori Domains

Let R be a domain and let Rωg be the ω-global transform of R. In this note it is shown that if R is a Mori domain, then the t-dimension formula t- dim(Rωg) = t-dim(R)-1 holds.     

微商共同作用在半素环的Lie理想上的结果

本文讨论了微商共同作用在半素环的某个Ｌｉｅ理想上的问题。给出了如下结果：设Ｒ是带有中心Ｚ（Ｒ）的半素环,Ｑｍｒ是Ｒ的极大右商环,Ｌ是Ｒ的非交换Ｌｉｅ理想,ｄ和δ是Ｒ的微商,假设ｒＲ（「Ｌ,Ｌ」）＝０且ｄ（ｘ）ｘ－ｘδ（ｘ）∈Ｚ（Ｒ）对任意ｘ∈Ｌ成立,则在Ｒ的扩张形心Ｃ中存在一个幂等元ｅ使得ｄ（１－ｅ）Ｑｍｒ＝０和δ（１－ｅ）Ｑｍｒ）＝０并且ｅＱｍｒ满足Ｓ４。另外给出微商共同作用在半素环上多项式的结     

F.P.—维数的合冲定理

1984年,Ho Kuen Ng在[1]中给出了交换环与模的有限表现维数(简称为F.P.—维数)的定义及若干有意义的重要结果.从此,有限表现性的讨论成为环论的热门课题之一.作者在[2]中将有限表现维数推广到非交换环上.并利用有限表现维数刻划了凝聚环,在[3]中讨论了有限表现维数的换环定理.在[4]中讨论了笛卡尔方形上的有限表现维数.丁南庆在[5]中推广了有限表现维数,给出了一种新维数——模的有限生成维数,在[6]中讨论了有限表现模的对偶     

M_2(R)上的非线性Lie导子

设R是一个含有单位元的2无扰的交换环,M_2(R)是定义在R上的全矩阵代数,证明了M_2(R)上的每一个非线性Lie导子都可以表示成一个内导子,一个可加诱导导子和一个映所有二次换位子为零的中心映射的和.     

交换主理想整环上立方幂等矩阵的线性保持

设Ｒ（≠Ｆ_３）是特征不为２的交换主理想整环,Ｍ_ｎ（Ｒ）定义Ｒ上的ｎ×ｎ矩阵模,本文刻划当ｎ≥ｍ时从Ｍ_ｎ（Ｒ）到Ｍ_ｎ（Ｒ）的保持立方幂等矩阵的线性映射的形式,由此推广了Ｃｈａｎ和Ｌｉｍ的一个结果（［１,定理３］）．     

On Skew Triangular Matrix Rings

Let α be a nonzero endomorphism of a ring R, n be a positive integer and T_n(R, α) be the skew triangular matrix ring. We show that some properties related to nilpotent elements of R are inherited by T_n(R, α). Meanwhile, we determine the strongly prime radical, generalized prime radical and Behrens radical of the ring R[x; α]/(x~n), where R[x; α] is the skew polynomial ring.     

Finite Rings Whose Graphs Have Clique Number Less than Five

Let R be a commutative ring and Г(R) be its zero-divisor graph.We com-pletely determine the structure of all finite commutative rings whose zero-divisor graphs have clique number one,two,or three.Furthermore,if R≌ Ri × R2 × … Rn (each Ri is local for i =1,2,3,…,n),we also give algebraic characterizations of the ring R when the clique number of r(R) is four.     

TRANSCENDENTAL AND ALGEBRAIC EXTENSIONS OF COMMUTATIVE RINGS

Abstract

Transcendental and algebraic elements over commutative rings are defined. Rings with zero nil radical are considered. For a transcendental over R, necessary and sufficient conditions are derived for elements of R[α] to be algebraic or transcendental over R. For R a ring with identity and a finite number of minimal prime ideals, necessary and sufficient conditions are given for any element in a unitary overring of R to be algebraic or transcendental over R. It is proved that if α is algebraic Over R, so is every element of R[α]. It is show that if R is Noetherian, β is algebraic over R[α] and α is algebraic over R, then, under certain conditions, β is algebraic over R. If R has a finite number of minimal prime ideals, P₁,…,P_k, which are pairwise comaximal, then if t is transcendental over R, R[t] can be obtained by adjoining k algebraic elements a_i over R to R whose defining polynomials are in P_i [x], and conversely, if such elements are adjoined to R, they generate an element transcendental over R.     

具有奇异值分解性质的代数

设F为一个域,R为一个带有对合的F-代数,如果R上每一个矩阵都有奇异值分解(简称SVD),则称R为一个有SVD性质的F-代数.本文指出:R为一个有SVD性质的F-代数的充要条件是:R同构于R~+,或R~+上二次扩域,或R~+上四元数体((-1,-1)/R~+),其中R~+为R的对称元集合,并且R~+为一个Galois序闭域.     

交换环上的严格上三角矩阵代数上的Lie导子

设R是任意含单位元的交换环,N(R)为R上(n+1)×(n+1)严格上三角矩阵构成的代数．本文证明了当n≥3且2是R的单位时,N(R)上任意Lie导子D可以唯一的表示为D=D_d+D_b+D_c+D_x,其中D_d,D_b,D_c,D_x分别是N(R)上的对角,极端,中心和内Lie导子,在n=2的情况,我们也证明了N(R)上任意Lie导子D可以表示为对角,极端,内Lie导子的和。     

Rings with x(yz)=z(yx)

In non-associative rings the associative law is replaced by various weaker identities. In this paper the identity x.yz = z.yx is considered. Let R be a ring satisfying this identity. It is obvious that if R has an identity element, then R is both commutative and associative. It is shown that if R is prime, third power associative, 2-torsion free, and has a nonzero idempotent, then this idempotent must be an identity and hence R must be commutative and associative.     

由n次幂等矩阵确定的交换幺半群

设R是含幺结合环,n≥2为自然数.对所有的k≥1,本文给出了n次幂等矩阵集Pk^n（R）={P｜P^n=P∈Mk（R）}上的一种等价关系,证明了P^n（R）=∪k=1^∞Pk^n（R）中的等价类在给定的加法运算下构成一个交换幺半群.     

Ordering Epic R-fields

We are concerned with the following problem. Given a ring R and an epic R-field K, under what conditions can K be fully ordered? Epic R-fields can be constructed in terms of matrices over R; this makes it natural to consider matrix cones over R rather than ordinary cones of elements of K. Essentially, a matrix cone over R, associated with a given ordering of K, consists of all square matrices which either become singular or have positive Dieudonné determinant over K. We give necessary and sufficient conditions in terms of matrix cones for (i) an epic R-field to be orderable, (ii) a full order on R to be extendable to a field of fractions of R and (iii) for such an extension to be unique.     

交换环上某些线性李超代数的理想

设Ｒ 是有１的交换环，２是Ｒ 的单位．设Ｌ 为环Ｒ 上的特殊线性李超代数或正交 辛李超代数．讨论了Ｌ 的理想与Ｒ 的理想的关系，证明了Ｌ 的所有理想都是标准的．