共查询到20条相似文献,搜索用时 15 毫秒
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As everyone knows, the classical Jackson theorem in approximation theory was generalized in Lp spaces by R. A. Devore[4]. In this paper, we proved the Jackson theorem in Ba spaces which introduced by Ding Xia Xi. 相似文献
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陈乃辉 《纯粹数学与应用数学》2008,24(2)
在随机函数的环境下,推广了经典函数逼近论中的Jackson逼近阶定理.建立了随机函数均方连续模的概念,并得到其有关性质后,研究了四种不同条件下随机函数被随机系数三角多项式逼近的阶之估计. 相似文献
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N. N. Pustovoitov 《Mathematical Notes》1992,52(1):709-716
This article considers the best approximation of a periodic function of several real variables by trigonometric polynomials with hyperbolic-cross harmonics. Theorems are proved on upper bounds for the indicated best approximation in terms of the modulus of continuity of the given function.Translated from Matematicheski Zametki, Vol. 52, No. 1, pp. 105–113, July, 1992. 相似文献
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H.Vaezi S.F.Rzaev 《逼近论及其应用》2002,18(3):79-85
In this article we consider the generalized shift operator defined by (Shuf)(g)=∫Gf(tut^-1g)dt on compact group G and by help of this operator we define “Spherical” modulus of continuity.So we prove Stechkin and Jackson type theorems. 相似文献
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N. N. Pustovoitov 《Mathematical Notes》1991,49(5):552-553
Translated from Matematicheskie Zametki, Vol. 49, No. 5, pp. 154–156, May, 1991. 相似文献
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O. I. Smirnov 《Mathematical Notes》1993,53(4):430-442
Translated from Matematicheskie Zametki, Vol., 53, No. 4, pp. 111–130, April, 1993. 相似文献
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J. Saint Raymond 《Archiv der Mathematik》2000,74(6):432-437
The aim of this note is to prove the following statement. It gives an extension of the theorem proved by O. Y. Borenshtein and V. S. Shul'man in [1]. 相似文献
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ON A MIN-MAX THEOREM 总被引:2,自引:0,他引:2
WUGUANGRONG HUANGWENHUA SHENZUHE 《高校应用数学学报(英文版)》1997,12(3):293-298
In this paper we prove a nonvariational form of a rain-max problem in [l] and give its application to a periodical problem. 相似文献
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Czechoslovak Mathematical Journal - We prove that for normal operators N1, $${N_2} \in {\cal L}({\cal H})$$ , the generalized commutator [N1, N2; X] approaches zero when [N1, N2; [N1, N2; X]] tends... 相似文献
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Institute of Mathematics, Hanoi. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 30, No. 3, pp. 93–94, July–September,
1996. 相似文献
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S. A. Gritsenko 《Mathematical Notes》1992,51(6):553-558
Translated from Matematichskie Zametki, Vol. 51, No. 6, pp. 32–40, June, 1992. 相似文献
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Svatoslav Staněk 《Journal of Differential Equations》1978,30(3):287-295
This paper gives a generalization of the Sturm comparison theorem for differential equations (p): y″ = p(t)y, (q): y″ = q(t)y under the assumption that the function p ? q changes its sign exactly once on [a, b] or ∝tbp ? q, ∝atp ? q maintain the sign on [a, b]. The results are used for investigating the distributions of zeros of solutions and the derivative of solutions of (p), (q). 相似文献
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Thomas Kaijser 《Acta Appl Math》1994,34(1-2):51-69
Starting from an old result of S. Karlin, we demonstrate the usefulness of couplings within the theory of random systems with complete connections. We also give a short exposé of some limit results for the state sequences associated to random systems with complete connections. 相似文献
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If A and B are bounded selfadjoint operators and AB is trace class, then the absolutely continuous part of A + B is unitarily equivalent to the direct sum of the absolutely continuous parts of A and B. 相似文献
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We extend Picard's theorem on the existence of elliptic solutions of the second kind of linear homogeneous -order scalar ordinary differential equations with coefficients being elliptic functions (associated with a common period lattice) to linear homogeneous first-order systems. In particular, the qualitative Floquet-type structure of fundamental systems of solutions in terms of elliptic and exponential functions, polynomials, and Weierstrass zeta functions of the independent variable is determined. Connections with completely integrable systems are mentioned.