TORSION-FREE ABELIAN GROUPS WITH FINITE RANK ENDOMORPHISM RINGS

Abstract

We show that if A and C are torsion-free abelian groups with ∩{ker f|f: A → C} = 0 = ∩{ker g|g: C → A}, and if A has a left Artinian quasi-endomorphism ring then A and C share a nonzero quasi-summand. Some consequences explored.     

有限Abel群的一个特征

本文证明了有限群Ｇ是Ａｂｅｌ群当且仅当Ｇ_ｒ满足下列条件：（Ⅰ） Ｇ有一个幂自同构 ａ使得 ＣＧ（ａ）是一个初等 ＡｂｅｌＺ一群．（Ⅱ）Ｇ没有子群与２－群＜ａ,ｂ｜ａ~２~ｎ＝ｂ~２~ｍ＝１,ａ~ｂ＝ａ~（１＋２）~（ｎ－１）＞同构,其中ｎ≥３,ｎ≥ｍ．利用该结果,作者还证明若有限群Ｇ有一个幂自同构ａ使得Ｃ_Ｇ（ａ）是一个初等Ａｂｅｌ２－群,则Ｇ是幂零群     

有限級有序加羣及有序環的表現

在另一文中,我们讨论了由全体2维實向量所成的有序环,在该文最後並说當维数n>2时(n为有限)也可类似地作初步讨论.为了显示这种向量环的用途,我们考虑用向量环来表现一般有序环的问题.在本文中我们证明:任一“n级的”(见以下定义)有序环都能与一个由若干n维實向量所组成的有序环同构.(主要在於证出关於n级有序加羣的类似结果.)我们希望有较好的结果,即:任一n级有序环都能与由全体n维實向量所成的一个有序环的一个子环同构,但未能证明或否定.     

短区间上非同构有限Abel群的个数

用算术函数ａ（ｎ）表示ｎ阶非同构Ａｂｅｌ群的个数，令Ａｋ（ｘ）＝∑／ｎ≤ｘ／ａ（ｎ）＝ｋ １，Ａｋ（ｘ；ｈ）＝Ａｋ（ｘ＋ｊ）－Ａｋ（ｘ）。     

ZERO-SUM PROBLEMS IN FINITE ABELIAN GROUPS AND AFFINE CAPS

For a finite abelian group G, let (G) denote the smallest integer l such that every sequence Sover G of length | S| l has a zero-sum subsequence of lengthexp (G). We derive new upper and lower bounds for (G), and all our bounds are sharp for special typesof groups. The results are not restricted to groups G of theform , but they respect the structure of the group. In particular, we show for all odd n, which is sharp if n is a power of3. Moreover, we investigate the relationship between extremalsequences and maximal caps in finite geometry.     

含指数为素数幂的超可解子群的有限群

本文讨论含指数为素数幂的超可解子群的有限群的结构．首先得到具有这种性质的非Abel有限单群的完全分类定理．其次给出了这类群是可解群和超可解群的若干充分条件．     

ON ABELIAN AUTOMORPHISM GROUPS OF SURFACES OF GENERAL TYPE

1.IntroductionItiswell-knownthatforacomplexcurveofgenusg22,itstotalautomorphismgroup(resp.abelianautomorphismgroup)isoforderS84(g-l)=42degKC(resp.S4g 4),whereKCisthecanonicaldivisorofC(cL[3,4]).Itisanintriguingproblemtogeneralisetheseboundstohigherdimensions.Severalauthorshavestudiedthisproblem(see[5,6]fordetails).Recently,Xiaohasgeneralisedtheseresultstosurfacesofgeneraltype,ingoodanalogywiththecaseofcurves.HehasprovedthatforacomplexminimalsmoothprojectivesurfaceSofgeneraltype,itstota1au…     

GROUPS WITH ALL PROPER SUBGROUPS (FINITE RANK)-BY-NILPOTENT. II

The authors obtain results concerning the structure of locally soluble-by-finite groups with all proper subgroups (finite rank)-by- nilpotent.     

关于交换群上的Cayley有向图的正规性

Cayley有向图X=Cay(G,S)叫做正规的,如果G的右正则表示R(G)在X的全自同构群Aut(X)中正规,我们定出了交换群上的小度数的非正规的Cayley有向图, 并给出了一个猜想．应用这个结果,给出了pn(n≤2)个点上的度数不超过3的有向对称图的分类,这里p是一个奇素数．     

ON COLEMAN OUTER AUTOMORPHISM GROUPS OF FINITE GROUPS

Let G be a finite group and OutCol(G) the Coleman outer automorphism group of G(for the definition, see below). The question whether OutCol(G) is a p′-group naturally arises from the study of the normalizer problem for integral group rings, where p is a prime.In this article, some sufficient conditions for OutCol(G) to be a p′-group are obtained. Our results generalize some well-known theorems.     

关于有限群的p-超可解性

本文研究了有限群的p-超可解性,利用子群的s-条件置换性及Sylow子群的极大子群对有限群结构的影响,得到了一个群为p-超可解群的一些充分必要条件.     

有限群的PCM-子群

本文研究了有限群的超可解性.利用Fitting子群的某些特殊子群的PCM性质对有限群结构的影响,获得了超可解群的一些充要条件.     

分裂扩张的稳定自同构群

本文给出有限群的分裂的Abel扩张的稳定自同构群的计算.作为应用,给出了循环群的半直积的自同构群的结构,它包括了若干已知结果,如文[1]的全部结果,并解决了[1]提出的问题.     

分裂扩张的稳定自同构群

本文给出有限群的分裂的Ａｂｅｌ扩张的稳定自同构群的计算．作为应用,给出了循环群的半直积的自同构群的结构,它包括了若干已知结果,如文［１］的全部结果,并解决了［１］提出的问题．     

ON PRODUCTS OF FINITE SUPERSOLUBLE GROUPS

In this paper two theorems of Kegel-Wielandt type are proved. As an application, we obtain sufficient conditions for m-permutable products of finite supersoluble groups to be supersoluble.