GCD整环与自反模

本文证明了凝聚整环是ＧＣＤ整环当且仅当秩为１的自反模是自由模．同时还得到有限弱整体维数的凝聚整环是ＧＣＤ整环当且仅当Ｐｉｃ（Ｒ）＝１．特别地，有限整体维数的Ｎｏｅｔｈｅｒ整环是ＵＦＤ当且仅当Ｐｉｃ（Ｒ）＝１．     

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．     

QF-环上有限生成模嵌入自由模的秩数和最小嵌入的算法

一个模嵌入自由模相当于用坐标来表示元素,这在数学上一直有重要意义．理论上, ＱＦ－环上的模都可以嵌入自由模,但没有好的算法,影响了它的应用．本文给出ＱＦ－环上有限生成模的最小嵌入的一种算法和所嵌入自由模的秩数的估计．     

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．     

Abel群环上的有限生成投射模

本文得到了有限生成投射ＲＧ－模为自由的充要条件，这里Ｂ为遗传环、零维环以及某些幂级数环，Ｇ为有限生成的Ａｂｅｌ群．     

Noether环上加性秩函数对应的Gabriel拓扑与相应商环的构造

本文利用［１］中建立的关系,给出了半素右Ｎｏｅｔｈｃｒ环上所有加性秩函数对应的Ｇａｂｒｉｅｌ拓朴与相应商环的构造,并建立了一般Ｎｏｅｔｈｅｒ环上加性秩函数与Ａｒｔｉｎ环上模范畴中的有限长之间的联系．     

有限生成平坦模的投射性和内射性

本文给出了每个有限生成平坦模内射，既投射又内射的环类的刻划．给出了每个有限生成平坦模既投射又内射这一环类的分类     

有限局部环上对称矩阵的计数定理(Ⅰ)

设A_n(R)是有限局部环Z/p~k Z上n阶对称矩阵的集合,这里n≥2．p是大于2素数,p≡1(mod4)且k＞1．通过确定有限局部环Z/p~k Z上对称矩阵的标准型,计算出A_n(R)在线性群GL_n(R)作用下的轨道数,从而计算出由特定对称矩阵确定的正交群的阶以及与特定对称矩阵在同一轨道的对称矩阵的阶．     

理想对称模

本文引进了理想对称模的概念,给出了理想对称模的系列等价刻画,用理想对称模给出了环R为理想对称环的若干等价条件,证明了对于环R的满足右Ore条件正则元的集S,如果S-挠自由R-模M是理想对称模,则M关于S的右分式模也是理想对称的,推广了理想对称环的相应结果.     

内射模的t－平坦性

设Ｒ为环，ｔ是左Ｒ－模范畴的一个遗传挠理论．文中证明了下述各点等价：（１）每个内射左Ｒ－模是ｔ－平坦的；（２）每个ｔ－有限表现左Ｒ－模的内射包络是ｔ－平坦的；（３）每个ｔ－有限表现左Ｒ－模是自由Ｒ－模的子模；（４）每个ｔ－有限表现左Ｒ－模是自反的且其对偶模是Ｈ－有限生成的．     

Symmetry classes of tensors and semi-direct product of finite abelian groups

In the study of symmetry classes of tensors, finding examples of symmetry classes of tensors that possess an o*-basis is of considerable interest. There are only few classes of groups that have been provided a necessary and sufficient condition for having such a basis. There is no general criterion for any finite group yet. In this note, we provide a necessary and sufficient condition for the existence of o*-basis of symmetry classes of tensors associated with semi-direct product of some finite abelian groups and, consequently, their wreath product.     

On the orthogonal basis of the symmetry classes of tensors associated with the dicyclic group

A necessary and sufficient condition for the existence of orthogonal basis of decomposable symmetrized tensors for the symmetry classes of tensors associated with the dicyclic group is given. In particular we apply these conditions to the generalized quaternion group, for which the dimensions of the symmetry classes of tensors are computed.     

On the orthogonal basis of the symmetry classes of tensors associated with the dicyclic group

A necessary and sufficient condition for the existence of orthogonal basis of decomposable symmetrized tensors for the symmetry classes of tensors associated with the dicyclic group is given. In particular we apply these conditions to the generalized quaternion group, for which the dimensions of the symmetry classes of tensors are computed.     

张量对称类上诱导线性算子的数值半径

设V是一个n维线性空间,V_x~m(G)为V上的张量对称类.A为V的线性算子T的矩阵,K(A)为V_x~m(G)上的诱导线性算子K(T)的矩阵.本文从K(A)的数值半径Υ(K(A))和可分数值半径Υ_x(K(A))定义出发,研究了Υ(K(A))、Υ_x(K(A))与范数||A||_p(1≤p≤2)、广义矩阵函数d_x~G(A)的关系,得到了它们之间的两个不等式.     

Orthogonal bases of Brauer symmetry classes of tensors for the dihedral group

In this article necessary and sufficient conditions are given for the existence of an orthogonal basis consisting of standard (decomposable) symmetrized tensors for the class of tensors symmetrized using a Brauer character of the dihedral group.     

Some Non-trivial Symmetry Classes of Tensors Associated with Certain Characters

Let G be a finite group and a set of n elements. Assume that G acts faithfully on and let V be a vector space over the complex field , with dim V = m 2. It is shown that for each irreducible constituent of permutation character of G, the symmetry class of tensors associated with G and is non-trivial. This extends a result of Merris and Rashid (see [6, Theorem 2]).1995 AMS subject classification primary 20C30 secondary 15A69This research was in part supported by a grant from IPM.     

Construction of orthonormal bases in higher symmetry classes of tensors

We present a method for constructing an orthonormal basis for a symmetry class of tensors from an orthonormal basis of the underlying vector space. The basis so obtained is not composed of decomposable symmetrized tensors. Indeed, we show that, for symmetry classes of tensors whose associated character has degree higher than one, it is impossible to construct an orthogonal basis of decomposable symmetrized tensors from any basis of the underlying vector space. We end with an open problem on the possibility of a symmetry class having an orthonormal basis of decomposable symmetrized tensors.     

The subspaces and orthonormal bases of symmetry classes of tensors

We present here the dimensions of some subspaces in the symmetry classes of tensors and some methods for constructing orthonormal bases of the symmetry classes of tensors.     

Symmetry classes of tensors associated with certain groups

We discuss the existence of an orthogonal basis consisting of decomposable vectors for some symmetry classes of tensors associated with certain subgroups of the full symmetric group The dimensions of these symmetry classes of tensors are also given