关于一类修正的三角插值多项式

本文构造出一个以｛θ_ｋ＝ｋ/(ｎ＋１)π｝^ｎ_ｋ＝１为插值节点的ｆ（θ）∈Ｃ_２π且为奇函数的修正的三角插值多项式Ｗ_n（ｆ;ｒ,θ）（ｒ为自然数）．Ｗ_n（ｆ;ｒ,θ）对每个以２π为周期的奇连续函数都能在全实轴上一致地收敛到ｆ（θ）;若ｆ（θ）∈Ｃ^ｊ_２π（０≤ｊ≤ｒ－１）且是奇的,Ｗ_n（ｆ;ｒ,θ）对其收敛阶均达到最     

Hermite-Fejr插值算子的平均收敛准则

给出了一个有用的判断Ｈｅｒｍｉｔｅ－Ｆｅｊéｒ插值算子Ｈｎ（ｆ,ｘ）平均收敛准则,即Ｈｎ（ｆ,ｘ）依范数收敛于ｆ（ｘ）的充分必要条件是：Ｈｎ（ｆ,ｘ）一致有界（对一切ｎ）并且Ｈｎ（ｆ,ｘｋ）依范数收敛于ｘｋ（ｋ＝１,２）．     

关于Hermite-Fejer插值过程的平均收敛

文［１］讨论了某些非Ｗ－过程的插值算子的加权平均逼近的收敛性和收敛阶．如记Ｈｎ（ｆ；ｘ）为以第二类Ｃｈｅｂｙｓｈｅｖ多项式Ｕｎ（ｘ）的零点作为插值节点，区间［－１，１］上的函数ｆ（ｘ）的Ｈｅｒｍｉｔｅ－Ｆｅｊｅｒ插值算子，［１］中证得：定理Ａ当０＜ｐ...     

相依样本下密度函数及其导函数的相合随机窗宽核估计

设（Ｘｎ）是Ｒ＾１中的平稳，强混合序列，具有公共的密度ｆ（ｘ），则可定义ｆ（ｘ）及其导函数ｆ＾（ｒ）（ｘ）的核估计与最近邻估计ｆ＾（ｒ）ｎ（ｘ）＝（ｎｈ＾ｒ＋１ｎ（ｘ））＾－１ｎ∑ｉ＝１Ｋ＾（ｒ）（Ｘｉ－Ｘ／ｈｎ（ｘ）），ｆｎ（ｘ）＝（ｎａｎ（ｘ））＾－１ｎ∑ｉ＝１Ｋ（Ｘｉ－ｘ／ａｎ（ｘ））其中核函数Ｋ（Ｘ）为取定的概率密度函数，且具有ｒ（ｒ≥０）阶导数，窗宽ｈｎ（ｘ）＝ｈｎ（ｘ；Ｘ１，．．．，Ｘ     

Baskakov-Durrmeyer型算子同时逼近的强逆不等式

本文对Ｂａｓｋａｋｏｖ－Ｄｕｒｒｍｅｙｅｒ型算子Ｍｎ（ｆ，ｘ）证明了，当１＜ｐ∞时，存在某一正数ｍ，使得ω２φｆ（２ｒ），１ｎｐＭ（‖Ｍ（２ｒ）ｎｆ－ｆ（２ｒ）‖ｐ＋‖Ｍ（２ｒ）ｍｎｆ－ｆ（２ｒ）‖ｐ＋１ｎ‖ｆ（２ｒ）‖ｐ，φ２（ｘ）＝ｘ（１＋ｃｘ）     

Hermne-Fejér插值算-T的平均收敛准则

给出了一个有用的有判断Ｈｅｒｍｉｔｅ－Ｆｅｊｅｒ插值算子Ｈｎ（ｆ,ｘ）平均收敛准则,即Ｈｎ（ｆ,ｘ）依范数收敛于ｆ（ｘ）的充分必要条件是：Ｈｎ（ｆ,ｘ）一致 有界（对一切ｎ）并且Ｈｎ（Ｆ,ｘ＾ｋ）依范数收敛于ｘ＾ｋ（ｋ＝１,２）。     

n阶时滞差分方程的边值问题

本文研究ｎ阶时滞差分方程的边值问题：ｘ（ｋ＋ｎ）＝ｆ（ｋ，ｘｋ（），ｘ（ｋ），ｘ（ｋ＋１），…，ｘ（ｋ＋ｎ－１）），ｋ∈ＩＴ，ｘ（ｍ）＝φ（ｍ），ｍ∈Ｉ－ｒ，ｘ（１）＝ａ１，ｘ（２）＝ａ２，…，ｘ（ｎ－２）＝ａｎ－２，ｘ（Ｔ）＝Ａ，｛得到了解的存在性和唯一性的结果．     

微积分拾零

微积分拾零千溪１连续函数中值性质诠释例设ｆ（ｘ）在［０，２π］上连续，且有ｆ（Ｏ）＝ｆ（２π），则存在使得．证明作（１）若Ｆ（０）＝０，则ｆ（０）＝ｆ（π），即．（２）若，则Ｆ（０）．Ｆ（π）＜０、由此知存在使得即把地球赤道的温度设想为连续变化是合理...     

一类插值多项式的导数逼近

本给出了以雅可比多项式的零点作为插值节点的一类插值多项式Ｂｎ（ｆ;ｘ）的导数逼近具有一阶连续导数的函数的收敛阶。并且指出ｌｉｍｎ→∞Ｂ′ｎ（ｆ;－１）≠ｆ′（－１）。     

P．Turán问题XXXV的一个注记

本文给出了有关Ｐ．Ｔｕｒáｎ，问题ＸＸＸＶ［关于逼近论的某些未解决的问题，Ｊ．ＡｐｐｒｏｘｉｍａｔｉｏｎＴｈｅｏｒｙ，１９８０，２９（１）：２３－８５］的一个结果．设ｒ＿（ｉｎ）（ｘ）为（０，２）插值的第一类基函数，其插值节点为（１－ｘ）（ｘ）之零点而Ｐ＿ｎ（ｘ）为ｎ次Ｌｅｇｅｎｄｒｅ多项式．那么．但对ｆ￣＊＝ｘ￣２却有     

RECENT PROGRESS ON SPHERICAL HARMONIC APPROXIMATION MADE BY BNU RESEARCH GROUP ——In memory of Professor Sun Yongsheng

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.     

On a class of self-similar processes with stationary increments in higher order Wiener chaoses

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.     

A REPRESENTATION FORMULA RELATED TO SCHR(O)DINGER OPERATORS

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.     

On a class of Riemann surfaces

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.     

Boundedness for commutators of multipliers on Hardy type spaces

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.     

A unified approach to certain problems of best local approximation

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.     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

<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     

Towards Excellence in Science Chinese Academy of Sciences

<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