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1.
侯绳照  侯晋升 《数学杂志》1999,19(3):318-322
设X为Banach空间,B(X)为ZH 有界线性算子全体组成的代数,本文给出了B(X)上保k次幂弱连续线性满足射的完全刻划。  相似文献   

2.
Hadamard积和酉不变范数不等式   总被引:9,自引:0,他引:9  
詹兴致 《数学进展》1998,27(5):416-422
设Mn,m是n×m复矩阵空间,Mn≡Mn,n.对于Hermite阵G,H∈Mn,GH表示G-H半正定.记A和B的Hadamard积为AB.本文证明了若A,B∈Mn正定,而X,Y∈Mn,m任意,则(XA-1X)(YB-1Y)(XY)(AB)-1(XY),XA-1X+YB-1Y(X+Y)(A+B)-1(X+Y).这推广和统一了一些现存的结果.设‖·‖为任意酉不变范数,I是单位矩阵.本文还证明了对于X∈Mn,m和A∈Mn,B∈Mm,若AI,BI,则函数f(p)=‖ApX+XBp‖在[0,∞)上单调递增.  相似文献   

3.
王勤 《数学杂志》1997,17(4):468-472
记X为复数域上无限维Banach空间,H为无限维复可分Hilert空间。本文给出B(X)上保持点谱的满射可加射具有的形式,以及B(H)上某些初等算子保点谱的充要条件。  相似文献   

4.
王卿文 《数学进展》1996,25(6):532-539
设F和Ω分别是一个任意的体和一个具有对合反自同构的有限维中心代数且charΩ≠2.本研究体上的下列矩阵方程:AX-XB=C,(1)AX-XB=C,(2)AX+XB=-C(3)分别给出了在Ω上(1)有一般解,(2)自共轭解及(3)有斜自共轭解的充要条件,并将W.E.Roth的相似定理推广到了任意的体F上。  相似文献   

5.
本文给出了算子方程AXB-X=C可解的若干充要条件,其中(A,B)为下列情形之一:A或B有闭值域;A(B*)有闭值域并且是单射或者相似于一个协亚正规算子并且B(A*)是单侧移位;A+(B(*+))幂有界,其值域R(A+) R(A)(R(B) R(B+)并且B(A*)是单侧移位;A=U*且B=U是Hardy空间上重数为1的单侧移位.而且,给出了解的表达式.  相似文献   

6.
鲁世杰 《数学进展》1996,25(6):510-516
本文给出了算子方程AXB-X=C可解的若干充要条件,其中(A,B)为下列情形之一A或B有闭值域;A(B)有闭值域并且是单射或或进相似于一个协亚规算子并且B(A)是单侧移位;A^+(B^+)幂有界,其值域R(A^+)包含于R(A)(R(B)包含于R(B^+)并用B(A)是单侧移位;A=U且B=U是Hardy空间上重数为1的单侧移位,而且,给出了解的表达式。  相似文献   

7.
独立随机变量序列重对数律的一个注记   总被引:1,自引:0,他引:1  
{X_i}为独立随机变量序列,E(X_i)<+∞,E(X (2)_(i))<+∞(i=1,2,…),当中心极限定理中的余项△n=O(ln Bnln ln Bn…(lnk Bn)~(1+δ)~(-1))时,本文得出结论:  相似文献   

8.
指数有界C-半群的共轭半群   总被引:7,自引:0,他引:7  
令S(t)是Banach空间X上的指数有界C-半群,S(t)是它在共轭空间X上的共轭半群.本文给出了X的一个闭子空间X+,使得S(t)在X+上的限制S+(t)是C|x+-半群,并给出了S+(t)的生成元.空间X+在某种意义上有极大性.  相似文献   

9.
对于公式秩(AB)≤min[秩(A),秩(B)],本文结合线性方程组给出一种简捷的证法.引理如果线性方程组AX=θ的解都是BX=θ的解,则秩(A)≥秩(B).证不妨设AX=θ的基础解系含有n-秩(A)个线性无关解,BX=θ的基础解系含有m-秩(B)个...  相似文献   

10.
一般增长曲线模型回归系数线性估计的泛容许性   总被引:3,自引:0,他引:3  
本文讨论一般的增长曲线模型;X=ABC+ε,E(ε)=0,Var(ε)=σΣV,其中X和ε是p×n价随机阵,A、C分别为p×q,k×n已知阵,Σ、V分别P、n阶已知非负定阵,B和σ为未知参数.在损失函数(d(X)-KBL)'(d(X)-KBL)下,我们给出了可估函数KBL的线性估计的泛(Φ)容许性定义,得到了DXF(DXF+M)在某些估计类中是KBL的泛容许性估计的充要条件.  相似文献   

11.
12.
As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years (2001-2005). The main topics are: convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.  相似文献   

13.
We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals.  相似文献   

14.
Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.  相似文献   

15.
In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p(R^n) into the Lebesgue space L^p with p 〈 1.  相似文献   

16.
In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.  相似文献   

17.
It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary.  相似文献   

18.
<正>August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists  相似文献   

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20.
<正>May 26,2014,Beijing Science is a human enterprise in the pursuit of knowledge.The scientific revolution that occurred in the 17th Century initiated the advances of modern science.The scientific knowledge system created by  相似文献   

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