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1.
非退化扩散过程的极性的必要性   总被引:3,自引:1,他引:2  
设X(t)是一N维非退化扩散过程.设 E(0,∞)和 F RN都为紧集.本文给出了:P(X-1(F)∩E≠φ)>0,P(X-1(F)≠φ)>0和P(X(E)≠φ)>0的充分条件.证明了:i)设 N≥ 3,a)若 dim(F)<N-2,则 P(X-1(F)=φ)=1; b)若dim(F)>N-2,则 P(X-1(F)≠φ)>0; c)存在 F1 RN,F2 RN,dim(F1)=dim(F2)=N-2,但有P(X-1(F1)=φ)=1,P(X-1(F2)≠φ)>0.ii)设N=1,a)若dim(E)>1/2,则x∈R1,P(X-1(x)∩E≠φ)>0;b)存在E(0,∞),dim(E)=1/2,使得x∈R1,P(X-1(x)∩E≠φ)>0.以上这些结果,不仅仅是Brown运动的推广,即使就Brown运动的情形而言,其中有些结果也是新的.  相似文献   

2.
值域有界的一类非线性算子不动点的带误差迭代逼近   总被引:9,自引:1,他引:8  
设X为一致光滑实Banach空间·T:X→X为连续强增生算子·f∈X·定义算子S:X→X为Sx=f-Tx+x,x∈X·设αn{}∞n=0与βn{}∞n=0为两个给定的实数列在(0,1)中且满足条件:(ⅰ)αn→0,βn→0(n→∞)·(ⅱ)∑∞n=0αn=∞·假设un{}∞n=0和vn{}∞n=0为X中两个序列且满足‖un‖=o(αn),‖vn‖→0(n→∞)·x0∈X,迭代序列xn{}定义为:(IS)xn+1=(1-αn)xn+αnSyn+unyn=(1-βn)xn+βnSxn+vn(n≥0){若Sxn{},Syn{}有界,则xn{}强收敛于S的唯一不动点  相似文献   

3.
设X=G0/K0是非紧致黎曼对称空间,G0的李代数g0是其复化李代数g的正规实型.若记n0=dimX,则我们在该文中证明:对于f∈Lp(X),1≤P≤2,当复数z满足Rez>δ(n0,P)=(n0-1)(1/P—1/2)时,f关于拉普拉斯算子本征函数展开的z阶Riesz平均几乎处处收敛于f.这一结论与经典的欧氏空间,以及复的和一秩的非紧致黎曼对称空间中完全相同.  相似文献   

4.
1引言与预备知识 设X为一实赋范线性空间.X·是X的对偶空间,正规对偶映射J:X→2X定义为:其中<·,·>表示X和X的广义对偶组.由[1]知若X是一致光滑Banach空间,则J(·)单值且在X的任何有界子集上为一致连续.我们用j(·)表示单值的正规对偶映射. 定义1[2]设K是X的一非空子集,算子T:K→X称为是 -强伪压缩的,如果存在一个严格增加函数 ,存在使得 定义2[2,3]T称为 强增生算子的,如果(I-T)是 -强伪压缩算子(其中I是恒等算子). 若定义1(相应地;定义2)中 (t)=k…  相似文献   

5.
PID环上矩阵模的保秩1映射及应用   总被引:1,自引:1,他引:0  
刘绍武 《数学杂志》1997,17(1):99-104
设R为含1主理想整环(简记为PID),本文刻划了矩阵模Mn(R)上保秩1线性映射的形式;作为其应用,给出了域上矩阵空间的保线性群及Mn(R)上保非零行列线性映射的形式,即它们为:T(X)=PXQ,A↑X∈Mn(R),或T(X)=PXtQ,A↑X∈Mn(R)。其中det(PQ)≠0。  相似文献   

6.
本文给出Lax定理在局部凸空间中的几个推广,特别地,我们获得Lax定理的如下推广:设X和Y为自反Frechet空间,其拓扑分别由半范序列q1≤q2≤…和半范序列p1≤P2≤…所给出.设A:Y→X′为连续线性算子,则存在连续线性算子G:Y′→X使满足:(Gg,Ay)=(g,y),g∈Y′,V∈Y当且仅当:对于n,存在cn>0,使sup{1(Ay,x)|:qn(x)≤1}≤cnpm.(y),y∈Y且A的值域在互X′中具拓扑补,这里,X′和Y′分别记X和Y的强对偶.  相似文献   

7.
最佳L2局部逼近存在唯一的充分必要条件   总被引:1,自引:0,他引:1  
本文给出了最佳L2局部逼近的存在唯一性定理,设f∈L2(0,δ),Sn=span(u0,u1,...Un-1)C^n-1(0,δ),且detWn(u0,u1,...un-1;0)≠0,那么,当x→0时,网(Px(f,Sn)收敛于Sn中某元素P0(f,Sn)的充要条件为:f=Pn-1+h,其中Pn-1(t)=n-1∑i=1aiti(h,1)x=0(X^n),x→0,且P0(f,Sn)=UW^-1nA  相似文献   

8.
设A是Banach空间X上的自反算子代数,并且A的不变子空间格Lat A满足0+≠0和X_≠X,αA→A是环自同构.如果X是实空间,并且dim X±>1,则存在X上的线性有界可逆算子A,使得α(T)=ATA-1,T∈A;如果X是复空间,并且dim X±=∞,则α(T)=ATA-1,T∈A.其中AX→X是线性、或者共轭线性有界可逆算子.  相似文献   

9.
翟发辉 《数学学报》2001,44(2):307-310
本文证明了一类本质正规算子A'(Ω';1)(T∈A'(Ω';1),如果T满足(1)T,T|H(T)分别是本质正规算子;(2)σ(T)=Ω,ρF(T)∩σ(T)=Ω;(3)ind(T-λ)=-1,nul(T-λ)=0,λ∈Ω';(4)σ(T|H(T))是一完全集,这里Ω'是一连通的解析Cauchy域, Hl(T)= V{ker(T-λ)*:λ∈ρrs-F(T)}是模小紧相似的.  相似文献   

10.
命题设a1∈N+,a1≠10n(n=0,1,2,…).现构造数列{an}:ak+1是ak的各位数字的平方和.如果存在T∈N+,使得aT+1=a1,则称a1是周期为T的“周期数”.证明:(1)周期数有且只有4,16,37,58,89,145,42,20...  相似文献   

11.
12.
张丽娜  吴建华 《数学进展》2008,37(1):115-117
One of the most fundamental problems in theoretical biology is to explain the mechanisms by which patterns and forms are created in the'living world. In his seminal paper "The Chemical Basis of Morphogenesis", Turing showed that a system of coupled reaction-diffusion equations can be used to describe patterns and forms in biological systems. However, the first experimental evidence to the Turing patterns was observed by De Kepper and her associates(1990) on the CIMA reaction in an open unstirred reactor, almost 40 years after Turing's prediction. Lengyel and Epstein characterized this famous experiment using a system of reaction-diffusion equations. The Lengyel-Epstein model is in the form as follows  相似文献   

13.
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   

14.
In this paper, we study the explicit representation and convergence of (0, 1; 0)-interpolation on infinite interval, which means to determine a polynomial of degree ≤ 3n - 2 when the function values are prescribed at two set of points namely the zeros of Hn(x) and H′n(x) and the first derivatives at the zeros of H′n(x).  相似文献   

15.
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   

16.
正Guest Editors:Hong Chen,Shanghai Jiao Tong University,Shanghai,China Guohua Wan,Shanghai Jiao Tong University,Shanghai,China David Yao,Columbia University,New York,USA Scope:Healthcare delivery worldwide has been fraught with high cost,low efficiency and poor quality of patient care service.For the field of operations research(OR),healthcare offers some of the biggest challenges as well as best opportunities in  相似文献   

17.
18.
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   

19.
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   

20.
Due to the resolution of current laser technology, the accuracy of corneal topography as measured by the videokeratoscope is no longer adequate to provide precise enough data for refractive surgery or for the fitting of customized contact lenses. We present an algorithm for recovering corneal topography that makes use of modern differential geometric techniques and numerical descent in Sobolev spaces. We believe this algorithm may be used with the photo- and videokeratoscope to increase the accuracy of the recovered corneal topography.  相似文献   

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