检索结果-南通市图书馆

Strong uniqueness of best approximations in spaces of bounded linear operators

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china mathematics 2004年第3期47卷 339-351页

作者： LI Chong HE Jinsu department of mathematics, zhejiang university hangzhou 310027, china department of mathematics, zhejiang normal university Jinhua 321004, china 1. department of mathematics Zhejiang University 310027 Hangzhou China 2. department of mathematics Zhejiang Normal University 321004 Jinhua China

The present paper is concerned with problems of the strong uniqueness of the best approximation and the characterization of a uniqueness element in operator *** results on the strong uniqueness of the best approximation operatorfrom RS-sets are proved and the uniqueness element of a sun in the compactoperator space from c0 to c0 is characterized by the strict Kolmogorov's *** recent results due to Lewicki and others are extended and improved.

关键词： best approximation operator, RS-set, sun, strong uniqueness, uniqueness element.

The best quadrature based on given Hermite information for the Sobolev class KW^r[a,b]

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2006年第8期49卷 1146-1152页

作者： WANG Xinghua & YANG Shijun department of mathematics, zhejiang university, hangzhou 310028, china department of mathematics, hangzhou normal College, hangzhou 3.003., china department of mathematics Zhejiang University Hangzhou 310028 China department of mathematics Hangzhou Normal College Hangzhou 310036 China

As usual, denote by KWr[a,b] the Sobolev class consisting of every function whose (r-1)th derivative is absolutely continuous on the interval [a,b] and rth derivative is bounded by K a.e. In [a,b]. For a function f ∈ KWr[a,b], its values and derivatives up to r-1 order at a set of nodes x are known. These values are said to be the given Hermite *** work reports the results on the best quadrature based on the given Hermite information for the class KWr[a,b]. Existence and concrete construction issue of the best quadrature are settled down by a perfect spline interpolation. It turns out that the best quadrature depends on a system of algebraic equations satisfied by a set of free nodes of the interpolation perfect spline. From our another new result, it is shown that the system can be converted in a closed form to two single-variable polynomial equations, each being of degree approximately r/2. As a by-product,the best interpolation formula for the class KWr[a,b] is also obtained.

关键词： Sobolev class, Hermite information, perfect spline, optimal recovery, best quadrature.

On Holomorphic Automorphisms of a Class of Non-homogeneous Rigid Hypersurfaces in C^(N+1)

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of mathematics,Series B 2010年第2期31卷 201-210页

作者： Qingyan WU department of mathematics,Linyi normal university,Linyi 276005,Shandong,china department of mathematics,zhejiang university,hangzhou 310027,china department of mathematics Linyi Normal University Linyi 276005 Shandong China department of mathematics Zhejiang University Hangzhou 310027 China

The author determines the real-analytic infinitesimal CR automorphisms of a class of non-homogeneous rigid hypersurfaces in CN+1 near the origin,and the connected component containing the identity transformation of al... 详细信息

关键词： Real-analytic infinitesimal CR automorphisms Rigid hypersurfaces Holomorphic automorphisms

On solving equations of algebraic sum of equal powers

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2006年第9期49卷 1153-1157页

It is well known that a system of equations of sum of equal powers can be converted to an algebraic equation of higher degree via Newton's identities. This is the Viete-Newton theorem. This work reports the generalizations of the Viete-Newton theorem to a system of equations of algebraic sum of equal powers. By exploiting some facts from algebra and combinatorics,it is shown that a system of equations of algebraic sum of equal powers can be converted in a closed form to two algebraic equations, whose degree sum equals the number of unknowns of the system of equations of algebraic sum of equal powers.

关键词： algebraic sum of equal powers, Newton's identities, system of equations,roots of a polynomial.

Littlewood-Paley operators with variable kernels

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2006年第5期49卷 639-650页

作者： CHEN Jiecheng, DING Yong & FAN Dashan department of mathematics, zhejiang university (Xixi Campus), hangzhou 310028, china School of Mathematical Sciences, Beijing normal university, Beijing 100875, china department of mathematics, university of Wisconsin-Milwaukee, Milwaukee WI 53201, USA department of mathematics, Central china normal university, Wuhan 430074, china department of mathematics Zhejiang University [Xixi Campus] Hangzhou 310028 China School of Mathematical Sciences Beijing Normal University Beijing 100875 China department of mathematics University of Wisconsin-Milwaukee Milwaukee WI 53201 USA department of mathematics Central China Normal University Wuhan 430074 China

In this paper we study a certain directional Hilbert transform and the boundedness on some mixed norm spaces. As one of applications, we prove the Lp-boundedness of the Littlewood-Paley operators with variable kernels... 详细信息

关键词： directional Hilbert transform, Sobolev spaces, Littlewood-Paley operator,variable kernel.

A Sufficient Condition for a Smash Product as a Transfinite Left Free normalizing Extension and Its Application

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2000年第1期16卷 71-78页

作者： Fang Li department of mathematics,zhejiang university Xixi Campus,hangzhou 310028,P.R.chinaZhongkui Liu department of mathematics,Northwest normal university,Lanzhou 730070,P.R.china department of mathematics Zhejing University Xixi Campus Hangzhou 310028 P.R. China

In this paper,a sufficient condition is given under which the smash product A#H is a transfinite *** normalizing extension of an algebra ***,the result is applied to a skew semigroup ring,a skew group ring and the qua... 详细信息

关键词： Smash product Transfinite left free normalizing extension Skew semigroup ring Quantum group

The maximal super-singular integral operators on product spaces

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2011年第12期54卷 2615-2626页

作者： WANG Hui1 & CHEN JieCheng2,3, 1department of mathematics, Xidian university, Xi’an 710071, china 2department of mathematics, zhejiang normal university, Jinhua 321004, china 3department of mathematics, zhejiang university, hangzhou 310027, china 1. department of mathematics Xidian University Xi’an 710071 China2. Department of Mathematics Zhejiang Normal University Jinhua 321004 China3. Department of Mathematics Zhejiang University Hangzhou 310027 China

We study the maximal super-singular integral operator T＊Ω,α,β（f）（x,y）=sup ∈1〉0,∈2〉0｜∫｜u｜〉ε1,｜v｜〉ε2 b1（｜u｜）b2（｜u｜）Ω（u＇,u＇）/｜u｜^n＋α｜u｜^m＋β-f（x-u,y-u）dudu｜defined on all f ∈ S（R^n ×R^m）, where 0 ≤ α,β〈∞, b1 b2 ∈ L∞（R＋1 ）,Ω satisfies certain cancellation conditions and Ω∈L1（S^n-1×S^m-1）in the case α,β〉0;Ω∈L（log＋L）（S^n-1×S^m-1）in the case αβ=0 and α＋β 〉0. It is proved that, for 1〈p〈∞.T＊Ω,α,βis a bounded operator from the homogeneous Sobolev space Lα,β^p（R^n×R^m）to the Lebesgue space L^p（R^n×R^m）.

关键词： super-singular integral maximal operator product spaces

COMPUTING EIGENVECTORS OF normal MATRICES WITH SIMPLE INVERSE ITERATION

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2003年第5期21卷 657-670页

作者： Zhen-yue Zhang Tiang-wei Ouyang (department of mathematics, zhejiang university, Yuquan Campus, hangzhou 310027, china) department of mathematics Zhejiang University Yuquan Campus Hangzhou 310027

It is well-known that if we have an approximate eigenvalue A of a normal matrix A of order n, a good approximation to the corresponding eigenvector u can be computed by one inverse iteration provided the position, say kmax, of the largest component of u is known. In this paper we give a detailed theoretical analysis to show relations between the eigenvector u and vector Xk, k = 1, … ,n, obtained by simple inverse iteration, i.e., the solution to the system (A - I)x = ek with ek the kth column of the identity matrix I. We prove that under some weak conditions, the index kmax is of some optimal properties related to the smallest residual and smallest approximation error to u in spectral norm and Probenius norm. We also prove that the normalized absolute vector v = |u|/||u|| of u can be approximated by the normalized vector of (||x1||2, … ||xn||2)T- We also give some upper bounds of |u(k)| for those 'optimal' indexes such as Fernando's heuristic for kmax without any assumptions. A stable double orthogonal factorization method and a simpler but may less stable approach are proposed for locating the largest component of u.

关键词： Eigenvector Inverse iteration Accuracy Error estimation.

RATIONALITY OF THE OFFSETS TO ALGEBRAIC CURVES AND SURFACES　

在线全文

学校读者我要写书评

暂无评论

Applied mathematics(A Journal of Chinese Universities) 1994年第3期9卷 265-277页

作者： LU wei(department of Applied mathematics, zhejiang university, hangzhou 310027) 1. department of Applied mathematics Zhejiang University 310027 Hangzhou

ＲＡＴＩＯＮＡＬＩＴＹＯＦＴＨＥＯＦＦＳＥＴＳＴＯＡＬＧＥＢＲＡＩＣＣＵＲＶＥＳＡＮＤＳＵＲＦＡＣＥＳ￥ＬＵＷＥＩ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＺｈｅｊｉａｎｇＵｎｉｖｅｒｓｉｔｙ，... 详细信息

ＲＡＴＩＯＮＡＬＩＴＹＯＦＴＨＥＯＦＦＳＥＴＳＴＯＡＬＧＥＢＲＡＩＣＣＵＲＶＥＳＡＮＤＳＵＲＦＡＣＥＳ￥ＬＵＷＥＩ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＺｈｅｊｉａｎｇＵｎｉｖｅｒｓｉｔｙ，Ｈａｎｇｚｈｏｕ３１００２７）Ａｂ...

关键词： offsets genus rational parametrizations algebraic curves and surfaces quadric curves and surfaces cubics.