共查询到20条相似文献，搜索用时 31 毫秒
1.
We investigate limiting behavior as γ tends to ∞ of the best polynomial approximations in the Sobolev-Laguerre space WN,2([0, ∞); e−x) and the Sobolev-Legendre space WN,2([−1, 1]) with respect to the Sobolev-Laguerre inner product
and with respect to the Sobolev-Legendre inner product
respectively, where a0 = 1, ak ≥0, 1 ≤k ≤N −1, γ > 0, and N ≥1 is an integer. 相似文献
2.
We prove inequalities about the quermassintegralsV
k
(K) of a convex bodyK in ℝ
n
(here,V
k
(K) is the mixed volumeV((K, k), (B
n
,n − k)) whereB
n
is the Euclidean unit ball). (i) The inequality
holds for every pair of convex bodiesK andL in ℝ
n
if and only ifk=2 ork=1. (ii) Let 0≤k≤p≤n. Then, for everyp-dimensional subspaceE of ℝ
n
,
whereP
E
K denotes the orthogonal projection ofK ontoE. The proof is based on a sharp upper estimate for the volume ratio |K|/|L| in terms ofV
n−k
(K)/V
n−k
(L), wheneverL andK are two convex bodies in ℝ
n
such thatK ⊆L. 相似文献
3.
周泽华 《中国科学A辑(英文版)》2003,46(1):33-38
Let Un be the unit polydisc of Cn and φ= (φ1,...,φn? a holomorphic self-map of Un. Let 0≤α< 1. This paper shows that the composition operator Cφ, is bounded on the Lipschitz space Lipa(Un) if and only if there exists M > 0 such thatfor z∈Un. Moreover Cφ is compact on Lipa(Un) if and only if Cφ is bounded on Lipa(Un) and for every ε > 0, there exists a δ > 0 such that whenever dist(φ(z),σUn) <δ 相似文献
4.
Song Li 《中国科学A辑(英文版)》2003,46(3):364-375
The purpose of this paper is to investigate the refinement equations of the form
where the vector of functions ϕ=(ϕ
1..., ϕ
r
)
T
is in (L
p
(ℝ
s
))
r
, 1⩽p⩽∞, a(α), α∈ℤ
s
is a finitely supported sequence of r × r matrices called the refinement mask, and M is an s × s integer matrix such that lim→∞ M-n = 0. In order to solve the refinement equation mentioned above, we start with a vector of compactly supported functions φ
0∈(L
p
(ℝ
s
))
r
and use the iteration schemes f
n
:=Q
a
n
φ
0, n=1,2,..., where Q
n
is the linear operator defined on (L
p
(ℝ
s
))
r
given by
This iteration scheme is called a subdivision scheme or cascade algorithm. In this paper, we characterize the Lp-convergence of subdivision schemes in terms of the p-norm joint spectral radius of a finite collection of some linear operators
determined by the sequence a and the set B restricted to a certain invariant subspace, where the set B is a complete set of representatives of the distinct cosets of the quotient group ℤs/Mℤs containing 0. 相似文献
5.
A. S. Zhuk 《Journal of Mathematical Sciences》2008,150(3):2034-2044
Let M be either the space of 2π-periodic functions Lp, where 1 ≤ p < ∞, or C; let ωr(f, h) be the continuity modulus of order r of the function f, and let
, where
, be the generalized Jackson-Vallée-Poussin integral. Denote
. The paper studies the quantity Km(f − Dn,r,l(f)). The general results obtained are applicable to other approximation methods. Bibliography: 11 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 350, 2007, pp. 52–69. 相似文献
6.
Let A
0, ... , A
n−1 be operators on a separable complex Hilbert space , and let α0,..., α
n−1 be positive real numbers such that 1. We prove that for every unitarily invariant norm,
for 2 ≤ p < ∞, and the reverse inequality holds for 0 < p ≤ 2. Moreover, we prove that if ω0,..., ω
n−1 are the n roots of unity with ω
j
= e
2πij/n
, 0 ≤ j ≤ n − 1, then for every unitarily invariant norm,
for 2 ≤ p < ∞, and the reverse inequalities hold for 0 < p ≤ 2. These inequalities, which involve n-tuples of operators, lead to natural generalizations and refinements of some of the classical Clarkson inequalities in the
Schatten p-norms. Extensions of these inequalities to certain convex and concave functions, including the power functions, are olso
optained.
相似文献
7.
Bogdan Batko Jacek Tabor 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》1999,69(1):67-73
Let G be a commutative semigroup and letL be a complete Archimedean Riesz Space. Suppose thatF: G → L satisfies for somee ∈ L
+ the inequality
Then there exists a unique additive mappingA : G → L such that
As the method of the proof we use the Johnson-Kist Representation Theorem. 相似文献
8.
L. G. Arabadzhyan 《Mathematical Notes》1997,62(3):271-277
We study the solvability of the integral equation
, wheref∈L
1
loc(ℝ) is the unknown function andg,T
1, andT
2 are given functions satisfying the conditions
.
Most attention is paid to the nontrivial solvability of the homogeneous equation
.
Translated fromMatematicheskie Zametki, Vol. 62, No. 3, pp. 323–331, September, 1997.
Translated by M. A. Shishkova 相似文献
9.
CongWenLIU JiHuaiSHI 《数学学报(英文版)》2003,19(1):187-200
In 1993,Ahern,Flores and Rudin showed that,if f is integrable over the unit ball BC^n of C^n and satisfies∫BC^nfoφdv=f（φ（0)) for every φ∈Aut(BC^n),then f is M-harmonic if and only if n≤11.The present paper is about an analogous question in the context of the unit ball Bn of R^n as well as in the weighted setting. 相似文献
10.
V. E. Slyusarchuk 《Mathematical Notes》2000,68(3):386-391
Necessary and sufficient conditions for the Lipschitzian invertibility of the difference map
, wheref: ℝ → ℝ is a continuous function, in the spacesl
p
(ℤ, ℝ), where 1≤p≤∞, of two-sided numerical sequences are obtained.
Translated fromMatematicheskie Zametki, Vol. 68, No. 3, pp. 448–454, September, 2000. 相似文献
11.
P. Ding 《Journal of Mathematical Sciences》2006,137(2):4645-4653
Let p be a prime number, n be a positive integer, and ƒ(x) = axk + bx. We put
where e(t) = exp(2πit). This special exponential sum has been widely studied in connection with Waring’s problem. We write n in the form n
= Qk + r, where 0 ≤ r ≤ k − 1 and Q ≥ 0. Let α = ord
p(k), β = ord
p(k − 1), and θ = ord
p(b). We define
and J = [ζ]. Moreover, we denote V = min(Q, J). Improving the preceding result, we establish the theorem. Theorem. Let k ≥ 2 and n ≥ 2. If p > 2, then
. An example showing that this result is best possible is given. Bibliography: 15 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 322, 2005, pp. 63–75. 相似文献
12.
Let P be a non-negative, self-adjoint differential operator of degree d on ℝn. Assume that the associated Bochner-Riesz kernel s
R
δ
satisfies the estimate, |s
R
δ
(x, y)| ≤ C Rn/d(1+R1/d|x - y|-αδ+β)for some fixed constants a>0 and β. We study Lp boundedness of operators of the form m(P), m coming from the symbol class S
p
−α
. We prove that m(P) is bounded on LP if
. We also study multipliers associated to the Hermite operator H on ℝn and the special Hermite operator L on ℂn given by the symbols
. As a special case we obtain Lp boundedness of solutions to the Wave equation associated to H and L. 相似文献
13.
A. I. Zvyagintsev 《Mathematical Notes》1997,62(5):596-606
For functions satisfying the boundary conditions
, the following inequality with sharp constants in additive form is proved:
wheren≥2, 0≤1≤n−2,−1≤m≤1, m+1≤n−3, and1≤p,q,r≤∞.
Translated fromMatematicheskie Zametki, Vol. 62, No. 5, pp. 712–724, November, 1997.
Translated by N. K. Kulman 相似文献
14.
M. Felten 《Acta Mathematica Hungarica》2008,118(3):265-297
The paper is concerned with bounds for integrals of the type
, involving Jacobi polynomials p
n
(α,β)
and Jacobi weights w
(a,b)
depending on α,β, a, b > −1, where the subsets U
k
(x) ⊂ [−1, 1] located around x and are given by with . The functions to be integrated will also be of the type on the domain [−1,1] t/ U
k
(x). This approach uses estimates of Jacobi polynomials modified Jacobi weights initiated by Totik and Lubinsky in [1]. Various
bounds for integrals involving Jacobi weights will be derived. The results of the present paper form the basis of the proof
of the uniform boundedness of (C, 1) means of Jacobi expansions in weighted sup norms in [3].
相似文献
15.
Two-direction refinable functions and two-direction wavelets with high approximation order and regularity 总被引：2，自引：0，他引：2
Shou-zhi YANG~ You-fa LI Department of Mathematics Shantou University Shantou China 《中国科学A辑(英文版)》2007,50(12):1687-1704
The concept of two-direction refinable functions and two-direction wavelets is introduced. We investigate the existence of distributional(or L~2-stable) solutions of the two-direction refinement equation: (?)(x)=(?)p_k~ (?)(mx-k) (?)p_k~-(?)(k-mx), where m≥2 is an integer.Based on the positive mask {p_k~ } and negative mask {p_k~-},the conditions that guarantee the above equation has compactly distributional solutions or L~2-stable solutions are established.Furthermore,the condition that the L~2-stable solution of the above equation can generate a two-direction MRA is given.The support interval of (?)(x) is discussed amply.The definition of orthogonal two-direction refinable function and orthogonal two-direction wavelets is presented,and the orthogonality criteria for two-direction refinable functions are established.An algorithm for construct- ing orthogonal two-direction refinable functions and their two-direction wavelets is presented.Another construction algorithm for two-direction L~2-refinable functions,which have nonnegative symbol masks and possess high approximation order and regularity,is presented.Finally,two construction examples are given. 相似文献
16.
There are reverse inequalities for square functions of differences arising in ergodic theory and differentiation of functions.
For example, it is shown that if An is the usual average in ergodic theory, and (nk∶k=1,2,3,...) is an increasing lacunary sequence with no non-trivial common divisor, then one has for any p, 1<p<∞, there
is a constant Cp such that for all f∃ Lp(X),
. 相似文献
17.
Cubic elliptic functions 总被引：1，自引：1，他引：0
Shaun Cooper 《The Ramanujan Journal》2006,11(3):355-397
The function
occurs in one of Ramanujan’s inversion formulas for elliptic integrals. In this article, a common generalization of the cubic
elliptic functions
is given. The function g1 is the derivative of Ramanujan’s function Φ (after rescaling), and χ3(n) = 0, 1 or −1 according as n≡ 0, 1 or 2 (mod 3), respectively, and |q| < 1. Many properties of the common generalization, as well as the functions g1 and g2, are proved.
2000 Mathematics Subject Classification Primary—33E05; Secondary—11F11, 11F27 相似文献
18.
We consider semilinear partial differential equations in ℝ
n
of the form
|
$
\sum\limits_{\frac{{|\alpha |}}
{m} + \frac{{|\beta |}}
{k} \leqslant 1} {c_{\alpha \beta } x^\beta D_x^\alpha u = F(u)} ,
$
\sum\limits_{\frac{{|\alpha |}}
{m} + \frac{{|\beta |}}
{k} \leqslant 1} {c_{\alpha \beta } x^\beta D_x^\alpha u = F(u)} ,
相似文献
19.
Zhi Wen DUAN Kwang Ik KIM 《数学学报(英文版)》2007,23(6):1083-1094
This paper is concerned with a nonlocal hyperbolic system as follows utt = △u ＋ （∫Ωvdx ）^p for x∈R^N,t〉0 ,utt = △u ＋ （∫Ωvdx ）^q for x∈R^N,t〉0 ,u（x,0）=u0（x）,ut（x,0）=u01（x） for x∈R^N,u（x,0）=u0（x）,ut（x,0）=u01（x） for x∈R^N, where 1≤ N ≤3, p ≥1, q ≥ 1 and pq 〉 1. Here the initial values are compactly supported and Ω belong to R^N is a bounded open region. The blow-up curve, blow-up rate and profile of the solution are discussed. 相似文献
20.
The purpose of the paper is to study the behavior at infinity of Fourier-Laplace transforms of distributions or more generally
plurisubharmonic functions u in Cn with bounds of the form
|