首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
We obtain exact order estimates for the best M -term trigonometric approximations of the classes Bp,qW B_{p,\theta }^\Omega of periodic functions of many variables in the space L q .  相似文献   

2.
3.
We obtain order estimates for the best M-term trigonometric approximations of the classes $ B^{Omega }_{{p,{text{ $ B^{Omega }_{{p,{text{ of periodic functions of many variables in the space L q for several values of the parameters p and q.  相似文献   

4.
5.
6.
We obtain order-sharp estimates of best approximations to the classes $B_{p,\theta }^r$ of periodic functions of several variables in the space L q , 1 ≤ p, q ≤ ∞ by trigonometric polynomials with “numbers” of harmonics from step hyperbolic crosses. In the one-dimensional case, we establish the order of deviation of Fourier partial sums of functions from the classes $ B_{1,\theta }^{r_1 } $ in the space L 1.  相似文献   

7.
We obtain order estimates for the best trigonometric and bilinear approximations for the classesB p, r of functions of many variables.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 8, pp. 1097–1111, August, 1995.  相似文献   

8.
9.
We obtain estimates exact in order for the best approximations of the classes B ∞,θ r of periodic functions of two variables in the metric of L by trigonometric polynomials whose spectrum belongs to a hyperbolic cross. We also investigate the best approximations of the classes B p r , 1 ≤ p < ∞, of periodic functions of many variables in the metric of L by trigonometric polynomials whose spectrum belongs to a graded hyperbolic cross. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 10, pp. 1395–1406, October, 2006.  相似文献   

10.
Order-sharp estimates are established for the best N-term approximations of functions in the classes $B_{pq}^{sm} (\mathbb{T}^k )$ and $L_{pq}^{sm} (\mathbb{T}^k )$ of Nikol’skii-Besov and Lizorkin-Triebel types with respect to the multiple system of Meyer wavelets in the metric of $L_r (\mathbb{T}^k )$ for various relations between the parameters s, p, q, r, and m (s = (s 1, ..., s n ) ∈ ? + n , 1 ≤ p, q, r ≤ ∞, m = (m 1, ..., m n ) ∈ ? n , and k = m 1 + ... + m n ). The proof of upper estimates is based on variants of the so-called greedy algorithms.  相似文献   

11.
12.
Order-sharp estimates of the best orthogonal trigonometric approximations of the Nikol’skii-Besov classes B p,θ r of periodic functions of several variables in the space L q are obtained. Also the orders of the best approximations of functions of 2d variables of the form g(x, y) = f(x?y), x, y $\mathbb{T}$ d = Π j=1 d [?π, π], f(x) ∈ B p,θ r , by linear combinations of products of functions of d variables are established.  相似文献   

13.
Sommario Si definiscono gli spazi , dove δ è una metrica in n non necessariamente euclidea, e si generalizzano dei risultati di Campanato e Meyers relativi al caso della metrica euclidea. Lavoro eseguito nell'ambito del Gruppo di RicercaC del Comitato Nazionale per la matematica del C.N.R.  相似文献   

14.
Best-approximation estimates are obtained in the integral and uniform metric on classes of periodic functions of many variables, which are defined by restrictions imposed on the mixed generalized derivative introduced by Stepanets. In this case, theharmonic of trigonometric polynomials, which are used for approximation of the classes of functions under consideration, are taken from the so-called hyperbolic crosses.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 3, pp. 367–377, March, 1993.  相似文献   

15.
We obtain exact order estimates for the approximation of the classes B p,θ Ω of periodic functions of many variables in the space L q by using operators of orthogonal projection and linear operators satisfying certain conditions. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 5, pp. 692–704, May, 2006.  相似文献   

16.
Using Seiberg-Witten theory and rational blow-down procedures of R. Fintushel and R.J. Stern, we construct infinitely many irreducible smooth structures, both symplectic and non-symplectic, on the four-manifold for each integer n lying in the interval . Received: 17 January 2000 / Published online: 18 January 2002  相似文献   

17.
Rational proper holomorphic maps from the unit ball in ?2 into the unit ball ? N with degree 2 are classified, up to automorphisms of balls.  相似文献   

18.
Order estimates are obtained for the best approximations of the classesB 1, r in the spaceL q with 1<q< and classesB , r in a uniform metric. The behavior of Kolmogorov widths of the classesB p, r ,1<p, in the metric of L is studied.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 1, pp. 79–92, January, 1995.  相似文献   

19.
In this paper, following our previous studies, we investigate the renewal rewards process with respect to the necessity, credibility, chance measure and the expected value in which the random inter-arrival times and random rewards are characterized as weighted fuzzy numbers under \(t\) -norm-based fuzzy operations on \(\mathbb {R}^{p}\) and \(\mathbb {R}^{q}\,\,p,\,q \ge 1,\) respectively. Many versions of \(T\) -related fuzzy renewal rewards theorems are proved by using the law of large numbers for weighted fuzzy variables on \(\mathbb {R}^{p}\) . An application example is provided to illustrate the utility of the results.  相似文献   

20.
We prove that for each prime p, positive integer \(\alpha \), and non-negative integers \(\beta \) and \(\gamma \), the Diophantine equation \(X^{2N} + 2^{2\alpha }5^{2\beta }{p}^{2\gamma } = Z^5\) has no solution with N, X, \(Z\in \mathbb {Z}^+\), \(N > 1\), and \(\gcd (X,Z) = 1\).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号