共查询到19条相似文献,搜索用时 296 毫秒
1.
分类自同构群为射影辛群PSpn(q)的区传递2-(v,k,1)设计,得到如下定理:设D为一个2-(v,k,1)设计,G≤Aut(D)是区传递,点本原但非旗传递的.若q为偶数且n≥14,则GPSpn(q). 相似文献
2.
设G Aut(D)且Soc(G) =Sz(q) ,这里q=2 p,p为奇素数,若有Sz(q) 相似文献
3.
本文证明若^3D4(q)△G≤Aut(^3D4(q)),这里q是素数方幂,则G不能点传递作用在一个射影平面上. 相似文献
4.
设D为有限线性空间,且T G Aut(T),其中T是非交换单群,并且同构于^2B2(g),Cn(g)(n≥3),^3D4(g),E7(q),E8(q),F4(q),^2F4(q),G2(q),^2G2(q)。假设D不是射影平面,G线传递作用在D上,则T点传递。 相似文献
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7.
韩广国 《高校应用数学学报(A辑)》2007,22(4):483-490
分类自同构群的基柱为李型单群E8(q)的区传递2-(v,k,1)设计,得到如下定理:设D为一个2-(v,k,1)设计,G≤Aut(D)是区传递、点本原但非旗传递的.若q〉24√(krk-kr+1)f(这里kr=(k,v-1),q=p^f,p是素数,f是正整数),则Soc(G)≌/E8(q). 相似文献
8.
刘国杰安立坚张晓娇宋蔷薇 《数学的实践与认识》2022,(2):206-212
设N,H是任意的群.若存在群G,它具有正规子群N≤Z(G),使得N≌N且G/N≌H,则称群G为N被H的中心扩张.完全给出了当|N|=2,H为亚循环2群时,N被H的中心扩张得到的所有不同构的群. 相似文献
9.
在组合设计的研究领域中,如何构造具有给定参数的t-设计是一个重要而且困难的问题.利用设计的自同构群来构造t-设计是这一问题有效的解决方法之一.在本文中,设D=(X,B)是一个4-(q+1,5,λ)设计,G≤Aut(D)区传递地作用在D上且X=GF(q)∪{∞},这里GF(q)是q元有限域.设PSL(2,q)(?)G≤PTL(2,q).利用Kramer和Mesner的关于构造区组设计的一个结果和二维射影线性群作用在X的5-子集的集合上的轨道,得到了如下结果:(1)G=PGL(2,17)并且D是一个4-(18,5,4)设计;或(2)G=PSL(2,32)并且D是一个4-(33,5,4)设计;或(3)G=PTL(2,32)并且D是4-(33,5,5)和4-(33,5,20)设计之一. 相似文献
10.
二次极大子群中2阶及4阶循环子群拟中心的有限群 总被引:1,自引:0,他引:1
本文讨论2阶及4阶循环子群对群结构的影响.证明二次极大子群中2阶及4阶循环子群拟中心的有限群G同构于下列群之一:(1)G为2-闭群;(2)G为2-幂零群;(3)G≌S,;(4)G=PQ.其中P为2^4阶广义四元数群,Q≌C3;(5)G≌A5或SL(2,5). 相似文献
11.
二次极大子群中2阶及4阶循环子群拟正规的有限群 总被引:2,自引:0,他引:2
本文讨论2阶及4阶循环子群对群结构的影响.主要结果是下述定理:如果有限群G满足标题的条件,那么下列情形之一成立:(1)G有正规Sylow 2-子群;(2) G为 2-幂零;(3) G ≌ S4;(4) G=PQ,其中 P为阶 24广义四元数群, Q为 3阶循环群;(5) G ≌ A5或 SL(2,5). 相似文献
12.
Bl JianxingDepartment of Mathematics Liaoning University Shenyang China 《中国科学A辑(英文版)》2004,47(6):801-811
In this paper we prove that a finite group G is isomorphic to the finite projective special unitary group Un(q) if and only if they have the same order of Sylow r-normalizer for every prime r. 相似文献
13.
用P(G,λ)表示简单图G的色多项式.设G是一个给定的简单图,若对任意简单图H,当P(H,λ)=P(G,λ)时都有H和G同构(记为H≌G),则称图G是色唯一的.本文证明了以下结果:设n,k,△都为非负整数,其中k≥0,△∈{4,5},若n≥1/3k~2+1/3△~2-1/3k△-1/3k-1/3△+4/3,则完全三部图K(n,n+△,n+k)是色唯一的.同时还给出了一个猜想. 相似文献
14.
刘伟俊 《中国科学A辑(英文版)》2003,46(6)
A 2 - (v,k,1) design D = (P, B) is a system consisting of a finite set P of v points and a collection B of k-subsets of P, called blocks, such that each 2-subset of P is contained in precisely one block. Let G be an automorphism group of a 2- (v,k,1) design. Delandtsheer proved that if G is block-primitive and D is not a projective plane, then G is almost simple, that is, T ≤ G ≤ Aut(T), where T is a non-abelian simple group. In this paper, we prove that T is not isomorphic to 3D4(q). This paper is part of a project to classify groups and designs where the group acts primitively on the blocks of the design. 相似文献
15.
O. A. Alekseeva 《Algebra and Logic》2006,45(1):1-11
It is proved that if G is a finite group with an element order set as in the simple group 3D4(q), where q is even, then the commutant of G/F(G) is isomorphic to 3D4(q) and the factor group G/G′ is a cyclic {2, 3}-group.
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Translated from Algebra i Logika, Vol. 45, No. 1, pp. 3–19, January–February, 2006. 相似文献
16.
Barbara Priwitzer 《Monatshefte für Mathematik》1999,127(1):67-82
This paper deals with the so-called Salzmann program aiming to classify special geometries according to their automorphism
groups. Here, topological connected compact projective planes are considered. If finite-dimensional, such planes are of dimension
2, 4, 8, or 16. The classical example of a 16-dimensional, compact projective plane is the projective plane over the octonions
with 78-dimensional automorphism group E6(−26). A 16-dimensional, compact projective plane ? admitting an automorphism group of dimension 41 or more is clasical, [23]
87.5 and 87.7. For the special case of a semisimple group Δ acting on ? the same result can be obtained if dim , see [22]. Our aim is to lower this bound. We show: if Δ is semisimple and dim , then ? is either classical or a Moufang-Hughes plane or Δ is isomorphic to Spin9 (ℝ, r), r∈{0, 1}. The proof consists of two parts. In [16] it has been shown that Δ is in fact almost simple or isomorphic to SL3?ċSpin3ℝ. In the underlying paper we can therefore restrict our considerations to the case that Δ is almost simple, and the corresponding
planes are classified.
Received 10 February 1997; in final form 19 December 1997 相似文献
17.
Barbara Priwitzer 《Monatshefte für Mathematik》1999,68(5):67-82
This paper deals with the so-called Salzmann program aiming to classify special geometries according to their automorphism
groups. Here, topological connected compact projective planes are considered. If finite-dimensional, such planes are of dimension
2, 4, 8, or 16. The classical example of a 16-dimensional, compact projective plane is the projective plane over the octonions
with 78-dimensional automorphism group E6(−26). A 16-dimensional, compact projective plane ? admitting an automorphism group of dimension 41 or more is clasical, [23]
87.5 and 87.7. For the special case of a semisimple group Δ acting on ? the same result can be obtained if dim , see [22]. Our aim is to lower this bound. We show: if Δ is semisimple and dim , then ? is either classical or a Moufang-Hughes plane or Δ is isomorphic to Spin9 (ℝ, r), r∈{0, 1}. The proof consists of two parts. In [16] it has been shown that Δ is in fact almost simple or isomorphic to SL3?ċSpin3ℝ. In the underlying paper we can therefore restrict our considerations to the case that Δ is almost simple, and the corresponding
planes are classified. 相似文献
18.
Richard Bödi 《Geometriae Dedicata》1998,72(3):283-297
Smooth projective planes are projective planes defined on smooth manifolds (i.e. the set of points and the set of lines are smooth manifolds) such that the geometric operations of join and intersection are smooth. A systematic study of such planes and of their collineation groups can be found in previous works of the author. We prove in this paper that a 16-dimensional smooth projective plane which admits a collineation group of dimension d 39 is isomorphic to the octonion projective plane P2 O. For topological compact projective planes this is true if d 41. Note that there are nonclassical topological planes with a collineation group of dimension 40. 相似文献
19.
D. J. Benson 《Algebras and Representation Theory》1999,2(3):287-294
Let k be a commutative ring of coefficients and G be a finite group. Does there exist a flat k G-module which is projective as a k-module but not as a k G-module? We relate this question to the question of existence of a k-module which is flat and periodic but not projective. For either question to have a positive answer, it is at least necessary to have |k| ≥ ?ω. There can be no such example if k is Noetherian of finite Krull dimension, or if k is perfect. 相似文献