Abelian Group Gradings on Full Matrix Rings

For positive integers ? and n, several authors studied ?_?-gradings of the full matrix ring M _n (k) over a field k. In this article, we show that every (G × H)-grading of M _n (k) can be constructed by a pair of compatible G-grading and H-grading of M _n (k), where G and H are any finite groups. When G and H are finite cyclic groups, we characterize all (G × H)-gradings which are isomorphic to a good grading. Moreover, the results can be generalized for any finite abelian group grading of M _n (k).     

严格上三角矩阵李代数上的积零导子

设$F$ 为域, $n\geq 3$, $\bf{N}$$(n,\mathbb{F})$ 为域$\mathbb{F}$ 上所有$n\times n$ 阶严格上三角矩阵构成的严格上三角矩阵李代数, 其李运算为$[x,y]=xy-yx$. $\bf{N}$$(n, \mathbb{F})$ 上一线性映射$\varphi$ 称为积零导子,如果由$[x,y]=0, x,y\in \bf{N}$$(n,\mathbb{F})$,总可推出 $[\varphi(x), y]+[x,\varphi(y)]=0$. 本文证明 $\bf{N}$$(n,\mathbb{F})$上一线性映射 $\varphi$ 为积零导子当且仅当 $\varphi$ 为$\bf{N}$$(n,\mathbb{F})$ 上内导子, 对角线导子, 极端导子, 中心导子和标量乘法的和.     

可换环上上三角矩阵代数的若当自同构分解

设R是含单位元1和可逆元2的可换环,Tn+1(R)表示R上(n+1)×(n+1)级上三角矩阵全体所形成的矩阵代数.本文证明了T(R)的每一个若当自同构都可唯一的分解为图自同构,内自同构和对角自同构的乘积.     

Piecewise Hereditary Triangular Matrix Algebras

For any positive integer N,we clearly describe all finite-dimensional algebras A such that the upper triangular matrix algebras TN(A) are piecewise hereditary.Consequently,we describe all finite-dimensional algebras A such that their derived categories of N-complexes are triangulated equivalent to derived categories of hereditary abelian categories,and we describe the tensor algebras A (×) K[X]/(XN) for which their singularity categories are triangulated orbit categories of the derived categories of hereditary abelian categories.     

Decomposition of Jordan Automorphisms of Strictly Upper Triangular Matrix Algebra Over Commutative Rings

Over a 2-torsionfree commutative ring R with identity, the algebra of all strictly upper triangular n + 1 by n + 1 matrices is denoted by n ₁. In this article, we prove that any Jordan automorphism of n ₁ can be uniquely decomposed as a product of a graph automorphism, a diagonal automorphism, a central automorphism and an inner automorphism for n ≥ 3. In the cases n = 1, 2, we also give a decomposition for any Jordan automorphism of n ₁.     

Group Gradings on G 2

In this article, we describe all group gradings by a finite abelian group Γ of a simple Lie algebra of type G ₂ over an algebraically closed field F of characteristic zero.     

Existence of Gradings on Associative Algebras

In this article, we study the existence of gradings on finite dimensional associative algebras. We prove that a connected algebra A does not have a nontrivial grading if and only if A is basic, its quiver has one vertex, and its group of outer automorphisms is unipotent. We apply this result to prove that up to graded Morita equivalence there do not exist nontrivial gradings on the blocks of group algebras with quaternion defect groups and one isomorphism class of simple modules.     

可换环上上三角矩阵代数的局部若当导子和局部若当自同构

Let R be a commutative ring with identity, Tn （R） the R-algebra of all upper triangular n by n matrices over R. In this paper, it is proved that every local Jordan derivation of Tn （R） is an inner derivation and that every local Jordan automorphism of Tn（R） is a Jordan automorphism. As applications, we show that local derivations and local automorphisms of Tn （R） are inner.     

$(m,n)$-Igusa-Todorov 代数,IT-维数和三角矩阵代数

设$T$, $U$是两个Artin代数, $_U M_T$是$U$-$T$-双模.本文得到了三角矩阵代数$\Lambda=\left({\smallmatrix T&0\\ M&U \endsmallmatrix}\right)$是$(m,n)$-Igusa-Todorov的一个充要条件.我们还研究了$\Lambda$的IT维数.更具体地说,事实证明$$\max\{\ITdim T, \ITdim U\}\leqslant\ITdim \Lambda\leqslant\min\{\max\{\gldim T,\ITdim U\},\max\{\gldim U,\ITdim T\}\}.$$     

交换半环上三角矩阵代数的自同构

证明了如果尺是含有恒等元的交换半环，那么R上的n阶上三角矩阵代数的自同构都是内自同构．     

由 n×n 上三角Toeplitz矩阵所构成的 超循环矩阵族

在Feldman和Costakis所做的结果的基础上,进一步考虑了超循环算子族的一些问题,设Τ=(T_1,…,T_m)是一组由m个上三角Toeplitz复矩阵构成的矩阵组,给出了一个Τ是超循环的充分必要条件.     

Nonlinear Jordan Higher Derivations of Triangular Algebras

In this paper, we prove that any nonlinear Jordan higher derivation on triangular algebras is an additive higher derivation. As a byproduct, we obtain that any nonlinear Jordan derivation on nest algeb...     

上三角矩阵的线性交换映射的表示

设Trn(R)表示定义在实数域R上的n×n阶上三角矩阵的集合,φ是定义Trn(R)上线性映射.如果对任意X∈Trn(R)有Xφ(X)=φ(X)X成立,称φ是线性交换映射.本文利用初等的矩阵计算方法描述了当φ(I)=I时,线性交换映射φ的表示形式,而且给出了φ的Frobenius范数‖φ(X)‖F的估计.     

Group Gradings on Polynomial Algebras

Let k be a field. We consider gradings on a polynomial algebra k[X₁,…, X_n] by an arbitrary abelian group G, such that the indeterminates are homogeneous elements of nontrivial degree. We classify the isomorphism types of such gradings, and we count them in the case where G is finite. We present some examples of good gradings and find a minimal set of generators of the subalgebra of elements of trivial degree.     

Functional Identities on Upper Triangular Matrix Algebras

Let , be the algebra of upper triangular r×r matrices over field aF. We describe multilinear maps , where n≤r, such that [f(A,...,A), A]=0 for all , provided that |F| >n + 1. As an application of the results obtained, we describe linear automorphisms θ of such that [θ(A²), θ(A)]=0 for all . Translated from Itogi Nauki i Tekhniki, Seriya Sovremennaya Matematika i Ee Prilozheniya. Tematicheskie Obzory. Vol. 74, Algebra-15, 2000.     

三角代数上Lie三重导子的刻画

设u=Tri(A,M,B)是三角代数.证明了在一般的假设下,如果线性映射δ:u→u,满足对任意的U,V,W∈u且UV=UW=0(或U·V=U·W=0),有δ([[U,V],W])=[[δ(U),V],W]+[[U,δ(V)],W]+[[U,V],δ(W)],则对任意U∈u,δ(U)=φ(U)+h(U),其中φ:u→u是一个导子,线性映射h:u→Z(u),满足对任意的U,V,W∈u且UV=UW=0(或U·V=U·W=0),有h([[U,V],W])=0.     

极大三角代数的交换子和上同调

设M为闭极大三角代数S的σ-弱闭双边模且满足MS,证明了模M交换子C(A,M)= M．进而,如果MAlgLat S,得到H~n(S,AlgLat S)=H~n(S,M)(n≥1)；若dimH〧≤1,则H~n(S,M)=0．     

弱可约极大三角代数的上同调

In this paper, we introduce the concept of weakly reducible maximal triangular algebras φwhich form a large class of maximal triangular algebras. Let B be a weakly closed algebra containing 5φ, we prove that the cohomology spaces H^n(φ, B) (n≥1) are trivial.