一类无限群中局部幂零性的判定准则

设G是任意群,群G的Frattini子群nat(G)定义为G的所有极大子群的交.类似地,群G的另外两个特征子群nFrat(G)及R(G)分别定义为群G的所有极大正规子群及群G的所有正规的极大子群的交.本文通过对nat(G),nnat(G)及R(G)的相互包含关系的研究,得到CF-群或中心由多重循环群的扩张群中局部幂零性的一个判定准则.同时也讨论了在某些群类中若干种广义幂零性的等价性.     

弱s-置换性传递的有限群

群G被称为弱s-置换性传递的群,对于它的子群H和K,若H在K中弱s-置换,K在G中弱s-置换,则H在G中弱s-置换.本文给出弱s-置换性、弱s-补性传递的可解群的结构以及每一子群在G中弱s-置换、弱s-补的群的结构.     

Groups with the weak minimal condition for non-subnormal subgroups

Let G be a group with the property that there are no infinite descending chains of non-subnormal subgroups of G for which all successive indices are infinite. The main results are as follows. If G is locally nilpotent then either G is minimax or G has all subgroups subnormal; if G is a Baer group then all subgroups of G are subnormal. It is also proved that a generalised radical group with this property is soluble-by-finite and either is minimax or has all subgroups subnormal.     

直觉L模糊子群的刻画

本文研究了一个群G上的直觉L模糊子群.借助于L模糊集的截集,反模糊子群,得到了群G上的直觉L模糊子群的等价刻画.在直觉L模糊子群和群G上的子群族之间可以建立起一一对应.     

子群的θ-偶和群的结构

研究极大子群和2-极大子群的θ-偶对群结构的影响.设G是有限群,本文得到了:如果G的每一个极大子群M都有极大θ-偶(C,D),使MC=G且C/D是2-闭的,那么G可解;如果G的每一个2-极大子群H都有θ-偶(C,D),使C/D幂零且G=HC,那么G是幂零.     

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.     

Groups in which all subgroups have a fan of prescribed form

This paper deals with groups G containing a fixed subgroup M(G) such that for any noninvariant subgroup H of G there exists a fan whose basic subgroups are H and M(G). Arbitrary groups of this kind are described. Also studied are groups in which each noninvariant subgroup has a fan whose basic subgroups are all intermediate subgroups.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 9, pp. 1232–1236, September, 1990.     

关于一类极大子群的θ-偶

对于有限群G的极大子群M，令β（G：M）表示整除│G：M│的素因子个数，β（G）表示所有β（G；M）中的最大数．令μ（G）为使得β（G：M）=β（G）的极大子群的集合．通过对这一类极大子群的θ-偶赋予一定条件，得到了判断群G可解、超可解的新结果．     

能表示成四个真子群并的有限群

本文研究了子群覆盖问题.利用计算子群阶的方法,给出了能表示成p+1或p+2个真子群并的有限群G的结构,这里p是群G阶的最小素因子,从而推广了文献[1]中的结果.     

Some explicit bounds in groups with a finite number of non-normal subgroups

The number of conjugacy classes of non-normal subgroups is an invariant of a group G denoted by v{G). In this paper explicit upper bounds for the order of the commutator subgroup G' and for the index of the centre in G, [G : Z(G)] are given for a group G with only a finite number of non-normal subgroups. The bounds provided are functions of v(G) and the primes appearing as orders of elements of G.     

On groups with all proper subgroups finite-by-abelian-by-finite

Archiv der Mathematik - We show that if all proper subgroups of a locally graded group G are finite-by-abelian-by-finite, then G contains a finite normal subgroup N such that all proper subgroups...     

A Sufficient Condition for Mi-groups

In this note, we give a sufficient condition for Mi-group. In particular, we show that if a finite group G is the semidirect product of two subgroups with coprime orders, in which one is a Sylow tower group and its Sylow subgroups are all abelian, and the other is an Mi-group and all of its proper subgroups are also Mi-groups, then G is an Mi-group.     

A theorem on direct expansions of Abelian groups

The following assertion is proved: if the basis subgroups of the periodic part t(G) of a non-denumerable Abelian group G have the same cardinality as G, then each of the subgroups contains, as a subgroup of the same cardinality as G, a direct component of G. The restriction on the cardinality of G is essential.Translated from Matematicheskie Zametki, Vol. 14, No. 6, pp. 879–884, December, 1973.     

极小子群对有限群结构的影响

设Ｇ是一个有限群．Ｇ的极小子群如何影响群的结构是一个人们感兴趣的问题．在本文中,我们用极小子群的ｃ－正规的条件刻划群Ｇ的结构．我们推广了一些已知的结果．     

Determination of solvable algebraic groups by dense integral subgroups

Let G and G′ be triangularizable algebraic groups defined over the field Q of rational numbers, and let Γ ? G_Q and Γ′ ? G′_Q be dense subgroups of them containing integral subgroups of finite index. A study is made of the conditions under which a birational isomorphism of G and G′ follows from an abstract isomorphism of Γ and Γ′.     

关于有限群的Pronormal极小子群

利用有限群G的pronormal极小子群和Sylow子群正规化子中的素数阶弱左Engel元素得到了G成为p-幂零群、幂零群和超可解群的一些充分条件,这些结果推广了已知结论。     

n-极大子群为共轭可换的有限群

群G的子群H称为G的共轭可换子群,若HHg=HgH,对任意g∈G都成立,本文考查了n-极大子群为共轭可换时对有限群构造的影响.     

关于有限群子群的弱S-可补性

设G是一个有限群,H是G的一个子群.称H为G的一个s-置换子群,若对于G的任意Sylow子群P,成立HP=PH.称H为G的一个弱s-可补的子群.若存在G的一个子群T,使得G=HT且H∩T≤H_s G,其中H_s G是包含在H中的G的最大的s-置换子群.本文在假设G的某些子群是弱s-可补的前提下,得到了G的一个结构定理,并推广了许多近期的结果.     

Hartley Sets and Injectors of a Finite Group

Mathematical Notes - By a Fitting set of a group G one means a nonempty set of subgroups $$\mathscr{F}$$ of a finite group G which is closed under taking normal subgroups, their products, and...     

s-半置换子群对有限群的p-超可解性的影响

群G的子群H称为半置换的,若对任意的K≤G,只要（｜H｜,｜K｜）=1,就有HK=KH．H称为s-半置换的,若对任意的p｜｜G｜,只要（p,｜H｜）=1,就有PH=HP,其中P∈Sylp（G）．本文研究Sylow子群的极大子群及极小子群的s-半置换性对有限群的p-超可解性的影响．