同阶子群个数的集合为{1,p+1}的有限群的完全分类

应用有限群论的有关知识定出了同阶子群个数的集合为{1,p+1}的有限群的完全分类.

同阶子群个数之集为{1,3,4}的有限群

设G是一个有限群.n(G)表示群G中所有同阶子群的个数组成的集合.得出了当n(G)={1,3,4}时G的所有Sylow子群的结构.

同阶子群个数的集合为{1,m}的幂零群

把同阶的子群看作一类,并用n(G)表示G的同阶子群个数的集合.通过数量分析对n(G)={1,m}的幂零群进行了分类,完善了相关工作,得到了相关结果:如果G为有限幂零群且n(G)={1,m},那么G=H×P,这里H为G的循环正规Hall子群,P为G的Sylow p-子群.另外,下面结论之一成立:1)m=1+p,P同构于Cpn-1×Cp,Q8,M(n-1,1)(除D8)中的某一个,这里M(n-1,1)=<a,b apn-1=bp=1,ab=a1+pn-2>;2)m=1+p+p^2,P同构于C_p×C_p×C_p,M(2,1)*Cp2中的某一个,这里"*"表示中心积,M(2,1)=<a,b ap2=bp=1,a^b=a^(1+p)>.

The Automorphism Group of a p-Group of Order p^n with an Element of Order p^(n-2)

A finite p-group G is called an LA-group if |G|||Aut(G)| when G is non-cyclic and |G|>p^2. This paper shows that a p-group of order p^n with an element of order p^(n-2) is an LA-group.

Topology of unitary groups and the prime orders of binomial coefficients

Let c : SU(n) → PSU(n) = SU(n)/Zn be the quotient map of the special unitary group SU(n) by its center subgroup Z_n. We determine the induced homomorphism c*: H*(PSU(n)) → H*(SU(n)) on cohomologies by computing with the prime orders of binomial coefficients.