An asymptotic expansion in wavelet analysis and its application to accurate numerical wavelet decomposition

We consider a dilation operatorT admitting a scaling function with compact support as fixed point. It is shown that the adjoint operatorT*admits a sequence of polynomial eigenfunctions and that a smooth functionf admits an expansion in these eigenfunctions, which reveals the asymptotic behavior ofT* forn.Due to this asymptotic expansion, an extrapolation technique can be applied for the accurate numerical computation of the integrals appearing in the wavelet decomposition of a smooth function. This extrapolation technique fits well in a multiresolution scheme.     

Endpoint estimates for fractional integral associated to schrödinger operators on the heisenberg groups

Let ∠= -△H~n+ V be the Schrdinger operator on the Heisenberg groups H~n,where V is a nonnegative function satisfying the reverse Hlder inequality. In this article, the author obtains the BMO_∠ and BLO_∠ estimates of the fractional integrals associated to ∠.     

关于图的L(3,2,1)-标号问题

图G的L( 2 ,1 )标号是一个从顶点集V(G)到非负整数集的函数f(x) .使得若d(x ,y) =1 .则｜f(x) -f(y) ｜≥ 2 ;若d(x ,y) =2 ,则｜f(x) -f(y)｜≥ 1 .图G的L( 2 ,1 )标号数λ(G)是使得G有max{f(v) ∶v∈V(G) }=k的L( 2 ,1 )标号中的最小数k .本文将L( 2 ,1 ) 标号问题推广到更一般的情形即L( 3,2 ,1 ) 标号问题 .我们首先定义了图G的顶点 3 着色及图的 3 色数 χ3 (G)等有关概念 ,并推导出 3 色数 χ3 (G)的上界 ;然后根据 χ3 (G)与λ3 (G)的关系 ,得出了对一般图G ,有λ3 (G) ≤ 3maxH Gδ(H) (Δ2 -Δ 1 )这一一般关系式 ;最后证明了对一般平面图G ,有λ3 (G)≤ 1 5(Δ2 -Δ 1 ) ,并得出了其它几类平面图的λ3 (G)的上界 .     

Function Spaces Associated with Schrödinger Operators: The Pöschl-Teller Potential

We address the function space theory associated with the Schrödinger operator H = ?d²/dx² + V. The discussion is featured with potential V (x) = ?n(n + 1) sech²x, which is called in quantum physics Pöschl-Teller potential. Using a dyadic system, we introduce Triebel-Lizorkin spaces and Besov spaces associated with H. We then use interpolation method to identify these spaces with the classical ones for a certain range of p, q > 1. A physical implication is that the corresponding wave function ψ(t, x) = e^?itHf(x) admits appropriate time decay in the Besov space scale.     

Data analysis and representation on a general domain using eigenfunctions of Laplacian

We propose a new method to analyze and efficiently represent data recorded on a domain of general shape in by computing the eigenfunctions of Laplacian defined over there and expanding the data into these eigenfunctions. Instead of directly solving the eigenvalue problem on such a domain via the Helmholtz equation (which can be quite complicated and costly), we find the integral operator commuting with the Laplacian and diagonalize that operator. Although our eigenfunctions satisfy neither the Dirichlet nor the Neumann boundary condition, computing our eigenfunctions via the integral operator is simple and has a potential to utilize modern fast algorithms to accelerate the computation. We also show that our method is better suited for small sample data than the Karhunen–Loève transform/principal component analysis. In fact, our eigenfunctions depend only on the shape of the domain, not the statistics of the data. As a further application, we demonstrate the use of our Laplacian eigenfunctions for solving the heat equation on a complicated domain.     

带有无界势和一般时间频率的非周期离散非线性Schr#246;dinger方程：无穷多个孤立子

本文研究下面的非周期离散非线性Schrödinger 方程：
-Δu_n + v_nu_n - ωun = g_n（u_n）,n ∈ Z,
其中V = {v_n}_n∈Z 和g_n 都是非周期的,当|n| → +∞ 时,v_n → +∞,并且时间频率ω ∈ R 可以满足下面的任何一种情形：（1）ω 属于算子-Δ + V 的一个有限谱间隔;（2）ω < inf σ（-Δ + V）;（3）ω ∈ σ（-Δ+ V）,其中σ（-Δ+ V）表示-Δ+ V的谱. 本文将用一些局部条件（在无穷远或零处）来代替一些全局条件. 利用变化的喷泉定理,当非线性项在无穷远处是超线性时,本文得到这个方程的无穷多个非平凡孤立子,并且,也得到指数衰减的孤立子的存在性.     

Taylor Series Expansion in Discrete Clifford Analysis

Discrete Clifford analysis is a discrete higher-dimensional function theory which corresponds simultaneously to a refinement of discrete harmonic analysis and to a discrete counterpart of Euclidean Clifford analysis. The discrete framework is based on a discrete Dirac operator that combines both forward and backward difference operators and on the splitting of the basis elements $\mathbf{e}_j = \mathbf{e}_j^+ + \mathbf{e}_j^-$ into forward and backward basis elements $\mathbf{e}_j^\pm $ . For a systematic development of this function theory, an indispensable tool is the Taylor series expansion, which decomposes a discrete (monogenic) function in terms of discrete homogeneous (monogenic) building blocks. The latter are the so-called discrete Fueter polynomials. For a discrete function, the authors assumed a series expansion which is formally equivalent to the Taylor series expansion in Euclidean Clifford analysis; however, attention needed to be paid to the geometrical conditions on the domain of the function, the convergence and the equivalence to the given discrete function. We furthermore applied the theory to discrete delta functions and investigated the connection with Shannon sampling theorem (Bell Sys Tech J 27:379–423, 1948). We found that any discrete function admits a series expansion into discrete homogeneous polynomials and any discrete monogenic function admits a Taylor series expansion in terms of the discrete Fueter polynomials, i.e. discrete homogeneous monogenic polynomials. Although formally the discrete Taylor series expansion of a function resembles the continuous Taylor series expansion, the main difference is that there is no restriction on discrete functions to be represented as infinite series of discrete homogeneous polynomials. Finally, since the continuous expansion of the Taylor series expansion of discrete delta functions is a sinc function, the discrete Taylor series expansion lays a link with Shannon sampling.     

On spectral expansions of piecewise smooth functions depending on the geodesic distance

We consider the expansion of a piecewise smooth function depending on the geodesic distance to some point in the eigenfunctions of the Beltrami-Laplace operator on an n-dimensional symmetric space of rank 1. We show that if the expansion converges at this point, then the function must have continuous derivatives up to and including the order (n − 3)/2.     

SO(3)-Structures on 8-manifolds

Suppose that the Laplace operator of a complete Riemannian manifold admits two linearly independent real-valued eigenfunctions, which do not vanish simultaneously. Consider the complex-valued function with these functions as the real and imaginary parts. This last function never vanishes and defines a homotopically non-trivial map into the punctured complex plane.     

Eigenvalue asymptotics and exponential decay of eigenfunctions for Schrödinger operators with magnetic fields

We consider the Schrödinger operator with magnetic field,

Assuming that and is locally in certain reverse Hölder class, we study the eigenvalue asymptotics and exponential decay of eigenfunctions.

     

一类非线性薛定谔方程的多解的存在性

本文讨论了如下一类非线性薛定谔方程：-△u＋V（x）u=f（u）,x∈R^N,在H^1（R^N）中无穷多解的存在性,其中N≥3,V（x）是RN上的实值连续函数并且满足对（A）x∈R^N,V（z）≥V0＞0.     

Fredholm Integral Equations of the First Kind and Topological Information Theory

The Fredholm integral equations of the first kind are a classical example of ill-posed problem in the sense of Hadamard. If the integral operator is self-adjoint and admits a set of eigenfunctions, then a formal solution can be written in terms of eigenfunction expansions. One of the possible methods of regularization consists in truncating this formal expansion after restricting the class of admissible solutions through a-priori global bounds. In this paper we reconsider various possible methods of truncation from the viewpoint of the ${\varepsilon}$ -coverings of compact sets.     

半单复形IMv(M,Q)

设M ,V ,Q是李普希茨流形 ,M是V的局部LIP平坦的紧子流形 ,V是开流形且dimV =dimQ .设U是M在V中的某开邻域且Δn 是Rn 中n维标准单形 .如f:Δn×U→Δn×Q是一个LIP浸入且P1f =P1,称f是一个n维单形 .令 (IMV(m ,Q) ) n 是上面所定义的所有n维单形的集合且令IMV(m ,Q) ={ (IMV(M ,Q) ) n} n 0 .本文证明了IMV(M ,Q)在我们所定义的面运算 i和退化运算Si下是一个半单复形 .     

Convergence of eigenfunction expansions at points of discontinuity of the coefficients of a differential operator

The question of the convergence of expansions in the eigenfunctions of a differential operator with discontinuous coefficients at a point x₀ of discontinuity of the coefficients is studied. Given an arbitrary function f(x) in the class L₂, a corresponding function \(\tilde f_{x_o } (x)\) is constructed which is such that at the point x₀ the eigenfunction expansion of f(x) diverges with the expansion of \(\tilde f_{x_o } (x)\) into a Fourier trigonometric series.     

关于几类图的L(2,1)标号问题

图G的L( 2 ,1 )标号是一个从顶点集V(G)到非负整数集的函数f(x) ,使得若d(x ,y) =1 ,则｜f(x) -f(y) ｜≥ 2 ;若d(x ,y) =2 ,则｜f(x) -f(y) ｜≥ 1 .图G的L( 2 ,1 ) 标号数λ(G)是使得G有max{f(v) ∶v∈V(G) }=k的L( 2 ,1 )标号中的最小数k .Griggs和Yeh猜想对最大度为Δ的一般图G ,有λ(G) ≤Δ2 .本文给出了Kneser图 ,Mycieklski图 ,Descartes图 ,Halin图的λ值的上界 ,并证明了上述猜想对以上几类图成立     

一类具有转移条件的不连续微分算子的渐近状态

研究一类具有转移条件且边界条件依赖于特征参数的Sturm-Liouville算子,建立一个与其相关的新的空间框架,给出其特征的相关性质与特征函数的完备性,利用函数论方法得出其特征的渐近表示,并获得Green函数的表达式.     

半线性热方程精确内部能控性

主要采用了构造辅助系统u′ △u=0的方法，同时也利用了强单调算子 的满射性。在条件（H)的修改下，得到在有限时间内的精确可控性，研究半线性热方程系统ey/et=△y-f(x,t,y,倒△y) h(x,t)的精确内部能控性。     

Riesz Bases of Eigenfunctions of an Integral Operator with a Variable Limit of Integration

We prove a theorem on the Riesz basis property in the space L ₂[0,1] of the eigenfunctions and associated functions of an integral operator whose kernel possesses a derivative discontinuous on the line $t = 1 - x$ .     

代數拓撲學中(μ,△,γ)-系統的正則同模論Ⅰ

<正> 設K與L為拓撲空間,又設f:K→L為連續映像.由f導出了準同模對應f~n:H~n(L,G)→H~n(K,G),n=1,2,…,其中H~n(L,G),H~n(K,G)表示上同調羣,而G表示係數環或域以γ_p~n(K)或者     

一类Schrǒdinger算子的谱分析

本文研究了Hilbert空间L^2（R^2）上由势函数V（x）（V≥0,连续）给出的一类Schrǒdinger算子H=-△＋V的谱。本文的主要结果：（1）H的谱σ（H）不会出现本性谱与离散谱交替出现的情况,其谱要么是离散的,要么从infσcos（H）开始全是本性谱;（2）lim‖x‖→∞V（x）=∞是σcos（H）=φ的充要条件。（3）借助于讨论H的Zhis-lin谱,在一定的条件下。lim‖x‖→∞V（x）=0是σcos（H）=[∞,0）的充要条件。我们还提出了几个没有解决的问题。