酉群的热核及应用

本文显式构造出了酉群Ｕ（ｎ），特殊酉群的ＳＵ（ｎ）的热核，作为应用定出了酉群的谱．     

A-稳定秩下的酉K1-群

A.Bak和唐国平在[1]中引入了Λ-稳定秩条件,这是比过去常用的酉稳定秩条件与绝对稳定秩条件都要弱的新的稳定秩条件.利用这一稳定秩条件证明了酉群(有限生成投射模上二次型的自同构群)的基本子群的正规性、二次型空间的消去性、以及酉K1-群的稳定性.这些结果不仅推广了已有的类似结果、极大地简化了证明过程,而更重要的是降低了稳定秩的下界.     

四元数群上的酉群的K1

令π表阶为8的四元数群,Zπ是π关于Z的群环,在Zπ上按自然方法定义一个对合映射“*”,并将“*”扩展为对合*_ω(仍记为*):x→ωx~*ω~(-1),x∈Zπ(ω=1,i,j,k)。定义K_1U~(-1)(Zπ)=U-1(Zπ)/EU-1(Zπ),K中U~(-1)(Zπ)=U_(2n)~(-1)(Zπ),EU~(-1)(Zπ)= EU_(2n)~(-1)(Zπ),而U_(2n)~(-1)(Zπ)={U∈GL_(2n)(Zπ)|UFU~*=F,F},EU_(2n)~(-1)(Zπ)为由初等酉阵生成的U_(2n)~(-1)(Zπ)的子群。主要结果是:(i)如果 Zπ上的对合是*ω,ω=i,j,k,则K_1U~(-1)(Zπ)=1;(ii)如果Zπ上的对合是*_1,则K_1U~(-1)(Zπ)=V,这里V表Klein 4元群。     

Λ-稳定秩下的酉K_1-群

A.Bak和唐国平在[1]中引入了Λ-稳定秩条件,这是比过去常用的酉稳定秩条件与绝对稳定秩条件都要弱的新的稳定秩条件.利用这一稳定秩条件证明了酉群(有限生成投射模上二次型的自同构群)的基本子群的正规性、二次型空间的消去性.以及酉K1-群的稳定性.这些结果不仅推广了已有的类似结果、极大地简化了证明过程,而更重要的是降低了稳定秩的下界.     

射影特殊酉群的纯数量刻画

证明了对每一个射影特殊酉群可用它的元的阶之集和群的阶加以刻画.     

有限局部环上酉群阶的计算

设K=F_(q^2),其特征为p, q=p^α,K有对合自同构ω:a→a^q. G是一个p 群，其阶为p^β, 群代数R=KG为一局部环. K的2阶自同构ω可延拓为R的一个2阶自同构，记为ω'，为方便，对任意a∈R, 记ω‘(a)为~a. R上2n级酉群定义为U_(2n)R={A∈GL_(2n)R|A(0,I^n,I^n,0)~A^t=(0,I^n,I^n,0)} 该文计算了U_(2n)R的阶.      

有限酉群作用下子空间轨道按和生成的格

设F_q2⁽ⁿ⁾是 F_q2上的 n 维行向量空间, U_n( F_q2)是 F_q2上的 n 阶酉群. 设M(m, r; n)是U_n(F_q2}作用下的一个子空间轨道, L(m, r; n)是 M (m, r; n)中子空间的和生成的集合.该文讨论了各个轨道生成的集合L(m, r; n)之间的包含关系, 给出了一个子空间是属于给定的由M(m, r; n)生成的集合L(m, r, n)中的一个元素的条件, 以及L}(m, r; n)做成几何格的条件.     

Hilbert K-模上酉群的框架表示

本文主要研究了Hilbert K-模上酉群的框架表示的一些基本性质，联系框架的强不相交性，得到了Hilbert K-模上酉群的框架表示的重数是有限的．     

特征不为 2 的有限域上酉群的极小生成元集

设K=Fq2为含有q2个元素的有限域,q为奇素数的幂,*：a→a*=aq是Fq2的一个二阶自同构．本文用几何方法证明了除K为F32而n=4的情形外,Fq2上的酉群Un（V）可由2个元素生成．     

一四元数矩阵方程组的广义酉矩阵解

给出了四元数矩阵方程组[XmnAns=Bns,XnnCnt=Dnt]有广义酉矩阵解的充要条件及其解集结构。     

On Unitary Equivalence of Analytic Toeplitz Operators

ＯｎＵｎｉｔａｒｙＥｑｕｉｖａｌｅｎｃｅｏｆＡｎａｌｙｔｉｃＴｏｅｐｌｉｔｚＯｐｅｒａｔｏｒｓＤｉｎｇＸｕａｎｈａｏ（丁宣浩）（ＤａｘｉａｎＴｅａｃｈｅｒ＇ｓＣｏｌｅｇｅ，Ｄａｘｉａｎ，Ｓｉｃｈｕａｎ，６３５０００）ＡｂｓｔｒａｃｔＩｎｔｈｉｓｐａｐ...     

矩阵酉扩张的刻划

本文用奇异值刻划了具有指定阶酉扩张的矩阵类，同时讨论了矩阵的正规扩张问题     

On the Unitary Binary Group

One consider the variety of the unitary binary group in n variables and it is shown that this algebraic variety is rational and it has n² parameters. Then it is given a parametrical rational representation of this variety.AMS Subject Classification (1991) 20G20     

Unitary rotation of square-pixellated images

The unitary rotation of square-pixellated images is based on the finite su(2)-oscillator model, which describes systems whose values for position, momentum and energy, are discrete and finite. In a two-dimensional position space, this allows the construction of angular momentum states, orthonormal and complete, for which rotations are defined as multiplication by phases that carry the rotation angle. The decomposition of a digital square images in terms of these angular momentum states determines a unitary (hence invertible) rotation of the image, whose kernel can be computed as a four-dimensional array of real numbers.     

Structure of Hyperbolic Unitary Groups I: Elementary Subgroups

This is the first in a series of papers dedicated to the structure of hyperbolic unitary groups over form rings and their subgroups. In this part, we recall foundations of the theory and study the elementary subgroup of the hyperbolic unitary group over a form ring. In particular, using a variant of Suslins patching method, we prove standard commutator formulae for relative elementary subgroups.2000 Mathematics Subject Classification: 20G35, 20H25     

Unitary Representations of the q-Virasoro Algebras

In the present paper we define an antilinear anti-involution ωof the q-Virasoro (Virq for short), and an Hermitian contravariant form of a Virq-module. For the irreducible module Vq(a,b) over Virq we give a necessary and sufficient condition for Vq(a,b) having a non-degenerate Hermitian contravariant form, and a necessary and sufficient condition for the Hermitian form being unitary.     

Unitary multiplier and dilation of projective isometric representation

In this paper we study unitary operator-valued multiplier σ on a normal subsemigroup S of a group G with its extension to G. A dilation of a projective isometric σ-representations of S to a projective unitary Φ(σ)-representation of G is established for a suitable unitary operator-valued multiplier Φ(σ) associated with the multiplier σ which is explicitly constructed during the study.     

Products of Quasi-Involutions in Unitary Groups

Given a regular ^–-hermitian form on an n-dimensional vector space V over a commutative field K of characteristic 2 ( ). Call an element of the unitary group a quasi-involution if is a product of commuting quasi-symmetries (a quasi-symmetry is a unitary transformation with a regular (n–1)-dimensional fixed space). In the special case of an orthogonal group every quasi-involution is an involution. Result: every unitary element is a product of five quasi-involutions. If K is algebraically closed then three quasi-involutions suffice.