自同构群

设Ｇ是有限群，ＡｕｔＧ＝ＡＢ，Ｂ△ＡｕｔＧ，（｜Ａ｜，｜Ｂ｜）＝１，Ａ是交换群且每Ｓｙｏｗ子群的秩≤２，Ｂ是循环群。本文得出了Ｇ的结构，特别地，证明了ＡｕｔＧ是秩≤的交换群时，Ｇ循环。     

2pq阶群的自同构群

继续「１～２」等的工作,给出了２ｐｑ阶群Ｇ的自同构群ＡｕｔＧ的准确构造。     

关于自同构群方程｜Aut(G)｜=p~2q~2

本文给出满足｜Ａｕｔ（Ｇ）｜＝ｐ２ｑ２的有限群Ｇ的完全分类，ｐ和ｑ是不同的素数．     

Camina—Gagen定理的一个推广

在这篇文章中，我们考虑２－（ｖ，ｋ，１）设计Ｄ上的自同构群，得到了如下结果：若Ｇ≤ＡｕｔＤ，且Ｇ是线一本原的，则当（ｋ，ｖ）＝ｋ／ｋ２时（ｋ２≤４），Ｇ也是点一本原的。ｋ２＝１是Ｃａｍｉｎａ－Ｇａｇ－ｅｎ的结果。     

Suzuhi单群作用在2－（v．k．1）上的一个特性

在本文，我们证明了：若群Ｇ满足Ｓｚ（２２ｍ＋１）≤Ｇ≤ＡｕｔＳｚ（２２ｍ＋１）ｍ≥１，且Ｇ作用在２－（ｖ．ｋ．１）设计上是线本原的，则Ｇ也是点本原的．     

关于具有给定Sylow子群正规化子的有限群Ⅱ

本文在有限可解群中解决了：任意ｍ－秩≤２的子群闭的局部群系具有性质：“如果群Ｇ的非单位Ｓｙｌｏｗ子群的正规化子属于，则群Ｇ也属于的一个充分必要条件．     

一类Reinhardt域的群不变函数与不变Kahler度量

本文把［１］的结果推广到更广泛的一类Ｒｅｉｎｈａｒｄｔ域Ｄ＝Ｄ（ｋ１ｋ２…ｋｐ）　Ｃ（１≤ｐ＜ｎ），即利用Ｄ的解析自同构群Ａｕｔ（Ｄ）下不变函数给出了域Ｄ在Ａｕｔ（Ｄ）下不变的Ｋａｈｌｅｒ度量．     

不充当自同构群的有限群

设ｐ为奇素数，本文将用一些新的技巧来证明，当Ｐ是阶小于Ｐ＾１１的交换Ｐ－群时，自同构群方程Ａｕｔ（Ｘ）＝Ｐ无解。这个结果使ＭａｃｈＨａｌｅ在１９８３年的工作得到了突破，并且我们所给的方法具有广泛性。     

一类3元生成的有限可解群

设Ｇ是个有限可解解，若对Ｇ的每个商群Ｈ，Ｈ的正规Ａｂｅｌ子群都是可以由２元生成的，则称Ｇ为ＡＤ２－群，在本文里，我们证明了：如果Ｇ是个ＡＤ２－群，那么Ｇ是３元生定的，且Ｇ＾（６）＝１。另外，我们举了２个例子，说明这些界都是最好的。     

Hyperabelian群的Abel子群

本文利用Ｄｉｒｉｃｈｌｅｔ单位定理证明了：设Ｇ是个Ｈｙｐｅｒａｂｅｌｉａｎ群．若Ｇ的亏数２的次正规Ａｂｅｌ子群都是有限生成的，则Ｇ是个多重循环群，且Ｇ的Ｈｉｒｓｃｈ数ｈ（Ｇ）ｎ２＋ｎ，其中ｎ是Ｇ的亏数２的次正规Ａｂｅｌ子群的最大０－秩．这个定理进一步推广了Ｍａｌｃ＇ｅｖ关于多重循环群的著名工作［５］．     

On amenability of two-generator groups

A discrete group G is amenable if there exists a finitely additive probability measure on G which is invariant under left translations and is defined on all subsets of G. It is proved that if the group is generated by two elements and is amenable then there are words being relators whose most of the consecutive pairs of the letters belong to a certain four-element set of pairs. This fact is applied to reproving non-amenability of a braid group. The same group provides an example showing that such type of condition is not su?cient for amenabilty.     

环的约化群与群环上的投射模

本文系统地研究群环的约化群，利用约化群刻划了群环上模的结构。主要结果：（１）Ｒ为交换半遗传环且Ｋ＿０Ｒ为挠群ｉｆｆ对任何有限生成半自反Ｒ－模Ｐ，ｓ＞０，使得．（２）设Ｒ为半局部Ｄｅｄｅｋｉｎｄ环，Ｇ为有限生成Ａｂｅｌ群，则Ｋ＿０ＲＧ为挠群ｉｆｆ如果Ｇ有素数ｐ阶元，则（３）如果Ｋ＿０ＲＧ为挠群，［Ｇ∶Ｈ］＜∞，则对任何，有．这里Ｒ为整环，Ｌ为其分式域。     

关于半clean群环

环$R$称为是半clean的, 是指环中的每个元素都是一个单位与一个周期元的和. clean环是半clean的. 刻画半clean群环的一般情形是不容易的. 我们的目的是考虑如下问题：若$G$ 是局部有限群或者是阶是3的循环群, 群环$RG$何时是semiclean的. clean群环上的一些已有结果被推广.     

Inverse Near Permutation Semigroups

A transformation semigroup over a set X with N elements is said to be a near permutation semigroup if it is generated by a group G of permutations on N elements and by a set H of transformations of rank N - 1. In this paper we give necessary and sufficient conditions for a near permutation semigroup S = ‹G,H›, where H is a group, to be inverse. Moreover, we obtain conditions which guarantee that its semilattice of idempotents is generated by the idempotents of S of rank greater than N - 2 or N - 3.     

The Round Functions of Cryptosystem PGM Generate the Symmetric Group

S. S. Magliveras et al. have described symmetric and public key cryptosystems based on logarithmic signatures (also known as group bases) for finite permutation groups. In this paper we show that if G is a nontrivial finite group which is not cyclic of order a prime, or the square of a prime, then the round (or encryption) functions of these systems, that are the permutations of G induced by the exact-transversal logarithmic signatures (also known as transversal group bases), generate the full symmetric group on G. This answers a question of S. S. Magliveras, D. R. Stinson and Tran van Trung. AMS Classification:94A60, 20B15, 20B20     

On a Group Acting Locally Freely on an Abelian Group

A group acting on an abelian group is finite provided that it is generated by a class of conjugate elements such that every two elements of the class generate a finite subgroup that acts freely.     

有限群的最大子群的性质对群结构的影响

有限群G的一个子群称为在G中是π-拟正规的若它与G的每一个Sylow-子群是交换的.G的一个子群H称为在G中是c-可补的若存在G的子群N使得G=HN且H∩N≤HG=CoreG(H).本文证明了:设F是一个包含超可解群系u的饱和群系,G有一个正规子群H使得G/H∈F.则G∈F若下列之一成立:(1)H的每个Sylow子群的所有极大子群在G中或者是π-拟正规的或者是c-可补的;(2)F*(H)的每个Sylow子群的所有极大子群在G中或者是π-拟正规的或者是c-可补的,其中F*(H)是H的广义Fitting子群.此结论统一了一些最近的结果.     

Generalizing alternative rings

We give an example of two groups G and H, generated by 2 and 3 elements, which satisfy G × Z ? H × Z.The groups G, H are semi-direct products of a torsion-free abelian group of rank 3 by an infinite cyclic group.     

On Centralizer Subalgebras of Group Algebras

Let $G$ be a finite group, $H ≤ G$ and $R$ be a commutative ring with an identity $1_R$. Let $C_{RG}(H) = \{ α ∈ RG|αh= hα$ for all $h ∈ H \}$, which is called the centralizer subalgebra of $H$ in $RG$. Obviously, if $H = G$ then $C_{RG}(H)$ is just the central subalgebra $Z(RG)$ of $RG$. In this note, we show that the set of all $H$-conjugacy class sums of $G$ forms an $R$-basis of $C_{RG}(H)$. Furthermore, let $N$ be a normal subgroup of $G$ and $γ$ the natural epimorphism from $G$ to $\overline{G}= G/N$. Then $γ$ induces an epimorphism from $RG$ to $R\overline{G}$, also denoted by $γ$. We also show that if $R$ is a field of characteristic zero, then $γ$ induces an epimorphism from $C_{RG}(H)$ to $C_{R\overline{G}}(\overline{H})$, that is, $γ(C_{RG}(H)) = C_{R\overline{G}}(\overline{H})$.     

Frattini子群是无限循环群的有限生成幂零群

完整地确定了Frattini子群是无限循环群的有限生成幂零群的结构,证明了下面的定理.设G是有限生成幂零群,则G的Frattini子群是无限循环群当且仅当G可以分解为G=S×F×T,其中F是秩为s的自由Abel群,T=Z_m_1⊕Zm_2⊕…⊕Z_m_u,m_1,m_2,…,m_u都是大于1的没有平方因子的自然数,m_1|m_2|…|m_u,■式中d_1,d_2,…,d_r都是正整数,d_1|d_2|…|d_r.进一步,(d_1,d2,…,d_r;s;m_1…,m_2,…,m_u)是群G的同构不变量,即若群H也是Frattini子群是无限循环群的有限生成幂零群,那么G同构于H的充要条件是它们有相同的不变量.