THE NUMBER AND SIZE OF ORBITS OF SOME PERMUTATION GROUPS

Abstract

It is shown that Aut ?, the group of homeomorphisms of the rational numbers with the usual topology, has 2 ^N_o orbits on the power set P(?). We call S ? ? a moiety if S and its complement in ? are infinite. It is shown that the orbit of any moiety S under Aut ? has cardinality 2^N_o while the orbit of S under Aut(?, ≤), the group of order preserving automorphisms of ?, has cardinality N_o if and only if S is a finite union of disjoint rational intervals with rational endpoints.     

计算对称群Sn的所有幂零子群

本文研究了对称群Sn的所有幂零子群的计算方法.利用添加生成元的方法,获得了S7的全部5119个幂零子群.结果表明此方法是有效的.     

THE FISCHER-CLIFFORD MATRICES OF THE GROUP 26: SP 6(2)

Abstract

The smallest Fischer sporadic simple group F₂₂ has 14 maximal subgroups up to conjugacy as listed in [2] and [15]. The group 2⁶: SP ₆(2) is a maximal subgroup of F ₂₂ of index 694980. We use the technique of the Fischer-Clifford matrices to constuct the character table of the group 2⁶: SP ₆(2). The Fischer-Clifford matrices of 2⁶: SP ₆(2) are used, together with the character tables of SP ₆(2) and a maximal subgroup 2⁵:S ₆ SP ₆ (2) of index 63, to construct the character table of 2⁶: SP ₆ (2).     

ON DEFINABILITY OF NORMAL SUBGROUPS OF A SUPERSTABLE GROUP

In this note we treat maximal and minimal normal subgroups of a superstable group and prove that these groups are definable under certain conditions. Main tool is a superstable version of Zil'ber's indecomposability theorem. MSC: 03C60.     

计算对称群Sn的所有极大子群

本文采用理论分析与编程判断相结合的方法,获得了Sn的全部极大子群的生成元及子群的阶等结果. 并将结果用于Sn(n＝2,3,4,5,6)进行验证,表明了程序判断的正确性,对计算结果进行归纳获得了Sn的递归定义及Sn可由二元生成等结果,可为进一步研究抽象群提供方便.     

TWO RESULTS ON GENERALIZED CHROMATIC NUMBERS

Abstract

The m'th chromatic number X_m(G) of a graph G is the least number of colours required to colour the vertices of G such that no m-clique of G is mono-coloured. For each k ≥ 2 and m ≥ 2 we determine for which r a graph G with m'th chromatic number k and clique number r exists. We also determine for which n a graph G exists with X_n (G + K) = X_m (G) = k.     

ON THE ROBEL SUBGROUPS OF LARGE TYPE

The author defines the large type Borel subgroups of a reductive algebraic goup,which are used to discuss Langlands' L-goups and the Langlands classification of the admissible representations of reductive algebraic groups over R(see[1,2,5]) and determine all of the Borel subgroups of large type for the classical semisimple Lie groups.     

群体决策随机偏爱数映射的若干性质

1引言近年来,群体决策在社会选择、福利、经济和军事等领域得到广泛应用,从而其理论研究越来越被人们所重视.20世纪中叶,K.J,Arrow提出了偏爱公理系和不可能性定理,并     

ON THE STRONG LAW OF LARGE NUMBERS

This paper introduces the concept of BC sequences and investigates some conditions which imply the strong law of large numbers for these sequences. The authors also study the strong law of large numbers for general random variable sequences. As applications of the result the authors characterize p-smoothableness of Banach space. Some generalizations of Petrov theorem, the Marcinkiewicz-Zygmund theorem and Hoffmann-Jorgensen and Pisier theorem are obtained.     

ON THE FUNCTIONAL-DIFFERENTIAL EQUATION OF THE DISTRIBUTION OF PRIME NUMBERS

1IntroductionsandStatementsInt-,iloIf)4-0'sCllorw'3I](see(ieVisme[4],Wright[:l]alldDriver[1])al,t}(}Inr)1,cdforil](lal[(lllrisl-,i(ital]yarlalyti(:itlI)rooftilt)prim(?number1,if(3or'3m5whi相似文献   

ON THE COADJOINT ORBITS OF MAXIMAL UNIPOTENT SUBGROUPS OF REDUCTIVE GROUPS

Let G be a simple algebraic group defined over an algebraically closed field of characteristic 0 or a good prime for G. Let U be a maximal unipotent subgroup of G and \( \mathfrak{u} \) its Lie algebra. We prove the separability of orbit maps and the connectedness of centralizers for the coadjoint action of U on (certain quotients of) the dual \( \mathfrak{u} \)* of \( \mathfrak{u} \). This leads to a method to give a parametrization of the coadjoint orbits in terms of so-called minimal representatives which form a disjoint union of quasi-affine varieties. Moreover, we obtain an algorithm to explicitly calculate this parametrization which has been used for G of rank at most 8, except E₈.When G is defined and split over the field of q elements, for q the power of a good prime for G, this algorithmic parametrization is used to calculate the number k(U(q); \( \mathfrak{u} \)*(q)) of coadjoint orbits of U(q) on \( \mathfrak{u} \)*(q). Since k(U(q), \( \mathfrak{u} \)*(q)) coincides with the number k(U(q)) of conjugacy classes in U(q), these calculations can be viewed as an extension of the results obtained in [11]. In each case considered here there is a polynomial h(t) with integer coefficients such that for every such q we have k(U(q)) = h(q). We also explain implications of our results for a parametrization of the irreducible complex characters of U(q).     

关于有理数域Q上多项式f(x)与f(xm)的Galois群的阶

确定有理数域Q上多项式f(x)的Galois群的阶是一件非常有意义的事情.本文把文献[1]中当m为奇数,多项式f(x)的Galois群的阶确定f(xm)的Galois群的阶的方法,推广到了m为偶时,对f(xm)的条件作进一步限制后,得到相同的结论.同时给出了m=2时,对f(x2)的条件削弱后的相应结论.     

SOME ALMOST ALL RESULTS CONCERNINGTHE PJATECKII-SAPIRO PRIME NUMBERS

51.IntroductionSupposethatr>Oisafixednumberand[oldenotes,asusuaI,theintegralpartofo.LetForo1wasfirststudiedin1953byPjateckii-Sapiro[']whoprovedthat(1.1)holdsfor1相似文献   

THE MAXIMAL NUMBER OF I_π-CHARACTERS OVER NORMAL SUBGROUPS

Let G be a π-separable group for a set of primes, let N be a normal subgroup of G, and let θ be an Iπ-character(i.e., irreducible π-partial character) of N. We obtain a necessary and suffcient condition for the number of Iπ-characters of G over θ to take the possible maximum |G : N |π. Some applications are given.     

关于n—可解群与n—幂零群的两个结果

本文证明了下面主要结果：设Ｇ是ｎ－可解群，π是一些素数之集，若对任意ｐ∈∩π（Ｇ），（ｐ，ｎ（１－ｎ））＝１，则Ｇ的π－Ｈａｌｌ子群的个数ｒ＝ｋ１ｋ２．．．ｋｔ，每ｋｉ≡１（ｍｏｄｐ），某Ｐ∈π，且每ｋｉ整除Ｇ的一个主因子。     

有限群中素数方幂阶子群的个数

本文利用基础代数中有关稳定子、陪集等理论,给出了有限群G中pk阶子群个数的 一个结果.     

ON THE VITALI-HAHN-SAKS-NIKODYM THEOREM

Abstract

The classical Vitali-Hahn-Saks-Nikodym Theorem [5, Thm. I.4.8] gives a limit criterion for when a sequence of strongly additive vector measures on a σ-field of sets having their range in a Banach space can be expected to be uniformly strongly additive. In [16, Cor. 8], Saeki proved that the limit condition on the sequence of vector measures could be substantially weakened as long as the Banach space in play is “good enough”. Saeki's result was based upon his work on a class of set functions too large to have Rosenthal's Lemma at his disposal. In Section 2, we prove Saeki's result with Rosenthal's Lemma at the basis of our work and then augment our characterization of Banach spaces enjoying Saeki's result in [1] with another natural equivalent condition. In Section 3 we extend Saeki's result to Boolean algebras having the Subsequential Interpolation property.     

Doubly transitive permutation groups with abelian stabilizers

Summary We prove that any doubly transitive permutation group with abelian stabilizers is the group of linear functions over a suitable field. The result is not new: for finite groups it is well known, for infinite groups it follows from a more general theorem of W. Kerby and H. Wefelscheid on sharply doubly transitive groups in which the stabilizers have finite commutator subgroups. We give a direct and elementary proof.     

ON F-z-SUPPLEMENTED SUBGROUPS OF FINITE GROUPS

A subgroup H of a group G is called F-z-supplemented in G if there exists a subgroup K of G, such that G = HK and H∩K≤ Z∞F(G), where Z∞F(G) is the F-hypercenter of G. We obtain some results about the F-z-supplemented subgroups and use them to determine the structure of some groups.