Pointwise convergence of wavelets of generalized Shannon type

In this paper, a new result on pointwise convergence of wavelets of generalized Shannon type is proved, which improves a theorem established by Zayed.     

关于叶果洛夫定理证明的一个注记

给出了一种函数列收敛的等价刻画,并利用此等价刻画来给出实变函数中叶果洛夫定理的另一种证明方法.     

小波级数的部分和的逐点收敛性

对小波级数的部分和的逐点收敛性进行了讨论,通过引入函数空间L2r(R),研究了函数f∈L2r(R)的小波级数的部分和fn的r阶导数对f(r)的逐点逼近问题.当函数f(r)在点x处连续时,建立了逼近速度的一个精确估计,进而得到了相关的逐点收敛定理.其次,当点x为函数f(r)的第一类间断点时,建立了f(r)n对f(r)在点x处的左右极限的算术平均值的收敛速度的一个估计.     

带超级光滑噪声密度函数的小波自适应点态估计

利用小波方法在局部Holder空间中研究一类反卷积密度函数的点态估计问题.首先,针对超级光滑噪声给出该模型任一估计器的点态风险下界;其次,构造有限求和小波估计器,并证明其在超级光滑噪声条件下达到了最优收敛阶,即该估计器在点态风险下的收敛速度与下界一致.最后,还讨论了这类小波估计器的强收敛性.值得指出的是上述估计都是自适应的.     

Pointwise bounds of orthogonal expansions on the real line via weighted Hilbert transforms

We study pointwise bounds of orthogonal expansions on the real line for a class of exponential weights of smooth polynomial decay at infinity. As a consequence of our main results, we establish pointwise bounds for weighted Hilbert transforms which are of independent interest. Mathematics subject classifications (2000)  41A10, 42C05     

Approximation of Generalized Szasz—Mirakjan Operator

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Penalty function theory for general convex programming problems

A class of penalty functions for solving convex programming problems with general constraint sets is considered. Convergence theorems for penalty methods are established by utilizing the concept of infimal convergence of a sequence of functions. It is shown that most existing penalty functions are included in our class of penalty functions.     

Generalized Szász-Mirakjan Operator Approximation

In this paper we shall defin a kind of generahzed Szász-Mirakjan operator and discussits convergence and degree of approximation,extend some results got by J.Grof and Z.Ditzian.     

ON THE CONVERGENCE OF APPROXIMATION TO CAUCHY SINGULAR INTEGRALS BY WAVELETS

本文讨论了用周期小波对Ｈｏ．．ｌｄｅｒ空间进行的特征刻划，给出了Ｈｏ．．ｌｄｅｒ空间中的若干小波逼近性质，证明了用周期小波逼近Ｃａｕｃｈｙ型奇异积分时的一些收敛定理．     

向径函数的球面平均及其点态收敛性

设球面平均函数为Mt（f）（x）=∫s^n-1f（x-ty′）dσ（y′）,则当f∈L^p（R^n）是向径函数，n≥3,1〈p≤n/（n-1）时，lim（t→0）Mt（f）（x）=f（x）几乎处处成立。     

The convergence space of minimal USCO mappings

A convergence structure generalizing the order convergence structure on the set of Hausdorff continuous interval functions is defined on the set of minimal usco maps. The properties of the obtained convergence space are investigated and essential links with the pointwise convergence and the order convergence are revealed. The convergence structure can be extended to a uniform convergence structure so that the convergence space is complete. The important issue of the denseness of the subset of all continuous functions is also addressed.      

On a Characterization of Spaces of Differentiable Functions

In this paper, we generalize Bernstein's theorem characterizing the space by means of local approximations. The closed interval is partitioned into disjoint half-intervals on which best approximation polynomials of degree divided by the lengths of these half-intervals taken to the power are considered. The existence of the limits of these ratios as the lengths of the half-intervals tend to zero is a criterion for the existence of the th derivative of a function. We prove the theorem in a stronger form and extend it to the spaces .     

On the convergence of expansions in polyharmonic eigenfunctions

We consider expansions of smooth, nonperiodic functions defined on compact intervals in eigenfunctions of polyharmonic operators equipped with homogeneous Neumann boundary conditions. Having determined asymptotic expressions for both the eigenvalues and eigenfunctions of these operators, we demonstrate how these results can be used in the efficient computation of expansions. Next, we consider the convergence. We establish the key advantage of such expansions over classical Fourier series–namely, both faster and higher-order convergence–and provide a full asymptotic expansion for the error incurred by the truncated expansion. Finally, we derive conditions that completely determine the convergence rate.     

Expansion of entire functions into Lagrange series

This paper is devoted to the problem of representing entire functions, in spaces described by the order and the type of these functions, by Lagrange series that converge in the natural topology in these spaces; this topology is stronger than the topology of compact convergence. Translated fromMatematicheskie Zametki, Vol. 61, No. 1, pp. 119–124, January, 1997. Translated by M. A. Shishkova     

三元双正交小波滤波器的刻画

研究由三元双正交插值尺度函数构造对应的双正交小波滤波器的矩阵扩充问题.当给定的一对三元双正交尺度函数中有一个为插值函数时,利用提升思想与矩阵多相分解方法,给出一类三元双正交小波滤波器的显示构造公式和一个计算实例.讨论了三元双正交小波包的的性质.