广义Weyl代数的导子

讨论并确定了一类Weyl型结合及Lie代数A [D]= A Ä F [D]的导子代数, 其中A是特征0的域F上的具有单位元的交换结合代数, D是由A的局部有限的可交换的导子所成的有限维空间, 并且A 是D -单的, 而F[D]是D 的多项式代数.     

Witt型单李超代数

设F是特征p〉2的域,A是F上结合的超交换的代数,D是域为F上A的超交换的导子.设A×D=A[D]为Witt型李超代数.从环论的角度得到了Witt型李超代数为单代数的充分必要条件.     

Weyl型单代数

对于任意特征的域F上具有单位元的交换结合代数A和它的交换导子的子空间D的多项式代数F［Ｄ］,在张量空间A［Ｄ］=AÄF［Ｄ］中定义了Weyl型结合代数和Lie代数.证明了A［Ｄ］作为Lie代数(模去中心)或结合代数是单的充要条件是A为D-单的并且A［Ｄ］在A上的作用是忠实的.[KG*2]由此可构造出许多单代数.     

中心分次单代数

设M是交换Monoid，G是交换群，D是M-分次域．本文的结果是：(一)证明D上两个有有限分次维数的中心M-分次单代数之分次张量积仍是此类分次代数．(二)给出D上G-分次代数的Noether—Skolem型定理．     

强群分次环中的Mackey分解定理和Maschke定理

本文给出强群分次环中的Mackey分解定理和Maschke定理的一般形式,也给出了A与A_1的Jacobson根之间的一些关系。 本文中模均指右西模,G是有单位元1的群。A是有单位元1的交换环k上的一个有单位元1的结合代数。A称为强G-分次的,如果有k-模直和分解且满足A_gA_h=     

3阶全矩阵代数的H_8-模代数结构

设H_8是非交换非余交换的8维半单Hopf代数,C[K_4]是克莱因四元群的群代数,M_3(C)是复数域上的3阶全矩阵代数.通过方阵和方阵对的弱相似给出了同构意义下M_3(C)上全部的C[K_4]-模代数结构.在此基础上结合H_8与C[K_4]的关系,刻划了同构意义下M_3(C)上所有的H_8-模代数结构.     

H-余模代数,全积分和可分扩张

设A是H-余模代数．文[1]给出了一个Morita关系.本文讨论[1]中Morita映射[，]，（，）分别为满射的几个等价命题.特别地，（，）为满射当且仅当存在一类全积分.最后，研究了可裂扩张的性质和相应的等价命题．     

仿射合成代数的三角分解

设→△是一个仿射箭图,它的极小虚单根为n.设k是一个有限域,记A=k→△为k上关于箭图→△的路代数,而记c(A)为关于A的合成代数.由C.Ringel和J.Green的工作,c(A)揭示了A的表示与量子群有密切的关系.文[11]证明了对应于A的不可分解表示可以分成预投射,正则,和预内射三个部分,C(A)具有一个三角分解.[11]中的证明需要假设维数向量为n的拟单模存在,而对于|k|=2,→△是→Dn型和→Em型(m=6,7,8)的情形,此假设不满足.本文的目的是给出一个简化的,而且不需要前面所提假设的证明.由此,得到一个与域k无关的c(A)的三角分解.     

三角代数上的交换零点ξ-Lie高阶可导映射

设u是数域F上的一个三角代数.若D={d_k}_(k∈N)是u上的一个交换零点ξ-Lie(ξ≠1)高阶可导映射且d_k(1)=0,■k∈N~+,则D是高阶导子.     

注重基础 追求简捷

文 [1]在不等式的证明中 ,灵活地运用数形结合的思想方法 ,化难为易 ,化隐为显 ,证明代数不等式 ,是那样巧妙、简明 ,使读者饱览了数学领域中数与形的和谐美、统一美 .读后受益非浅 .笔者对该文例题作进一步的思考 ,发现换一个角度 ,用代数方法来证明 ,也能体现解题过程的简捷明了 .可与构图法殊途同归 ,相映成趣 .下面给出该文四个例题的代数解法 .用到的都是基础知识 .例 1　正数 a、b、c、A、B、C,满足 a A=b B= c C=k,求证 :a B b C c A相似文献   

Derivations of generalized Weyl algebras

A class of the associative and Lie algebras A[D] = A F[D] of Weyl type are studied, where A is a commutative associative algebra with an identity element over a field F of characteristic zero, and F[D] is the polynomial algebra of a finite dimensional commutative subalgebra of locally finite derivations of A such that A is D-simple. The derivations of these associative and Lie algebras are precisely determined.     

Niveau hermitien de Certaines algèbres de quaternions

Let D [d] =(a,b/F) a quaternion divisior algebra over a field F of characteristic ? 2. Denote 1, i, j , k the basis of D, such that i²[d] n, j²[d] b, ij [d] -ji [d] k and A :D → D the involution given by i [d] -i, j [d] j (and k [d] k). In [LE] D. LEWIS asks the following question :Does there exist a quadratic Pfister form [S p. 721 [d] such that the hermitian form [d] [d] D is isotropic over (D, [d]) but not hyperbolic &; In this note, we show that the answer of this question is negative, so that the hermitien level [§I], when it is finite, of (D, A) is a power of two. This result holds for quaternion algebras with standard involution [LE].     

一类量子环面李代数的泛中心扩张

设Cq=Cq[x1^±1,x2^1]为复数域上的量子环面,其中q≠0是一个非单位根．D（Cq）为Cq的导子李代数．记Lq为Cq＋D（Cq）的导出子代数．本文研究李代数Lq的泛中心扩张．     

Koszul Differential Graded Algebras and BGG Correspondence II

The concept of Koszul differential graded （DG for short） algebra is introduced in [8]. Let A be a Koszul DG algebra. If the Ext-algebra of A is finite-dimensional, i.e., the trivial module Ak is a compact object in the derived category of DG A-modules, then it is shown in [8] that A has many nice properties. However, if the Ext-algebra is infinite-dimensional, little is known about A. As shown in [15] （see also Proposition 2.2）, Ak is not compact if H（A） is finite-dimensional. In this paper, it is proved that the Koszul duality theorem also holds when H（A） is finite-dimensional by using Foxby duality. A DG version of the BGG correspondence is deduced from the Koszul duality theorem.     

A fully invariant ideal of alternative algebras

Let ϕ be an associative commutative ring with 1, containing 1/6, and A be an alternative ϕ-algebra. Let D be an associator ideal of A and H a fully invariant ideal of A, generated by all elements of the form h(y, z, t, x, x)=[{[y, z], t, x}-, x]+[{[y, x], z, x}-, t], where [x, y]=xy−yx, {x, y, z}-=[[x, y], z]−[[x, z], y]+2[x,[y, z]]. Here we consider an ideal Q=H∩D and prove that Q⁴=0 in the algebra A. If A is unmixed, then HD=0, DH=0, and Q²=0 in particular. If A is a finitely generated unmixed algebra, then the ideal H lies in its associative center and Q=0. It follows that any finitely generated purely alternative algebra satisfies the identity h(y,z,t,x,x)=0. We also show that a fully invariant ideal H₀ of the unmixed algebra A, generated by all elements of the form h(x, z, t, x, x), lies in its associative center and H₀∩D=0. Consequently, every purely alternative algebra satisfies the identity h(x,z,t,x,x)=0. Translated fromAlgebra i Logika, Vol. 36, No. 3, pp. 323–340, May–June, 1997.     

REPRESENTATIONS OF AFFINE HECKEALGE BRAS OF TYPE G2

Let k be a field and q a nonzero element in k such that the square roots of q are in k. We use Hq to denote an affne Hecke algebra over k of type G2 with parameter q. The purpose of this paper is to study representations of Hq by using based rings of two-sided cells of an affne Weyl group W of type G2. We shall give the classification of irreducible representations of Hq. We also remark that a calculation in [11] actually shows that Theorem 2 in [1] needs a modification, a fact is known to Grojnowski and Tanisaki long time ago. In this paper we also show an interesting relation between Hq and an Hecke algebra corresponding to a certain Coxeter group. Apparently the idea in this paper works for all affne Weyl groups, but that is the theme of another paper.     

量子代数模的张量积与不可分解模

令M是Z[v]的由v-1和奇素数p生成的理想,U是A=Z[v]M上相伴于对称Cartan矩阵的量子代数.k是特征为零的代数闭域,A→k(v(?)ξ)是环同态.U_k=U(?)_Ak,u_k是U_k的无穷小量子代数.令ξ是1的p次本原根.本文证明了:若有限维可积U_k模M,V中至少有一个是内射模,或者M,V中有一个模作为u_k模是平凡的,则有U_k模同构M(?)V≌V(?)M.我们还证明了:若有限维可积U_k模V作为u_k模是不可分解的,有限维可积U_k模M是不可分解的,且M|_(uk)是平凡的,则V(?)M是不可分解U_k模.令V和M是有限维可积U_k模,作为u_k模是同构的且具有单基座,本文证明V和M作为U_k模也是同构的.由此得到:不可分解内射u_k模提升为U_k模是唯一的.     

基半群为0-J-严格单半群的零直并的代数

设Ａ是代数闭域ｋ上的一个具乘基Ｂ的有限维含幺结合代数，称半群Ｂ∪｛０｝为Ａ的基半群．本文给出了０ Ｊ 严格单半群的定义．对于基半群为０ Ｊ 严格单半群的零直并的代数，完全研究了它的代数表示型     

量子群的基变换与范畴同构

令Ｍ是Ｚ［ｖ］的由ｖ－１和奇素数ｐ生成的理想，Ｕ是Ａ＝Ｚ［ｖ］Ｍ上相伴于对称Ｃａｒｔａｎ矩阵的量子群， Ａ－Γ是环同态， Ｕг＝ＵＡΓ［Ｕг］是Ｕг的量子坐标代数，本文建立了量子坐标代数的基变换：即在相关约束条件下有Г－Ｈｏｐｆ同构 Ａ［Ｕ］ＡГ≌Г［Ｕг］．我们证明了有限秩 Ａ自由 １型可积 Ｕ模范畴和有限秩 Ａ自由 Ａ［Ｕ］余模范畴是同构的．特别，当 Г是域时，局部有限 １型 Ｕг模范畴和Г［Ｕг］余模范畴是同构的．最后，我们还证明了在［１］中定义的诱导函子和Ｂ．Ｐａｒｓｈａｌｌ与王建磐博士在［２］中研究的诱导函子的一致性．     

On Galois Extension of Hopf Algebras

Let H be a cosemisimple Hopf algebra over a field k, and π ： A→ H be a surjective cocentral bialgebra homomorphism of bialgebras. The authors prove that if A is Galois over its coinvariants B=LH Ker π and B is a sub-Hopf algebra of A, then A is itself a Hopf algebra. This generalizes a result of Cegarra [3] on group-graded algebras.