共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
We consider second-order subelliptic operators with complex coefficients over a connected Lie group G. If the principal coefficients are right uniformly continuous then we prove that the operators generate strongly continuous holomorphic semigroups with kernels K satisfying Gaussian bounds. Moreover, the kernels are Hölder continuous and for each 0, 1 and > 0 one has estimates
for g, h, k, l G and all z in a subsector of the sector of holomorphy with
where
denotes the canonical subelliptic modulus and D " the local dimension.These results are established by a blend of elliptic and parabolic techniques in which De Giorgi estimates and Morrey–Campanato spaces play an important role. 相似文献
3.
We establish a criterion for the existence of a solution of the interpolation problem f(
n
) = b
n in the class of functions f analytic in the unit disk and satisfying the relation
where : [1; +) (0; +) is an increasing function such that the function ln(t) is convex with respect to lnt on the interval [1; +) and lnt = o(ln(t)), t . 相似文献
4.
G. A. Kalyabin 《Functional Analysis and Its Applications》2004,38(3):184-191
We solve Tikhomirov's problem on the explicit computation of sharp constants in the Kolmogorov type inequalities
Specifically, we prove that
for all and k{0,...,n-1}. We establish symmetry and regularity properties of the numbers A
n,k
and study their asymptotic behavior as n for the cases k=O(n
2/3) and k/n(0,1).Similar problems were previously studied by Gabushin and Taikov. 相似文献
5.
Gerald Kuba 《Acta Mathematica Hungarica》2002,95(1-2):115-124
For a positive real parameter t, real numbers , , and
, we consider sums
, where
is the rounding error function, i.e.\
. Generalizing and improving the main result of Part I of the paper we show that there exists an absolute constant
such that
for all
, and all
. Further, we give applications concerning the circle problem with linear, polynomial, and general weight. 相似文献
6.
On the Range of the Aluthge Transform 总被引:1,自引:0,他引:1
Let
be the algebra of all bounded linear operators on a complex separable Hilbert space
For an operator
let
be the Aluthge transform of T and we define
for all
where T = U|T| is a polar decomposition of T. In this short note, we consider an elementary property of the range
of Δ. We prove that R(Δ) is neither closed nor dense in
However R(Δ) is strongly dense if
is infinite dimensional.
An erratum to this article is available at . 相似文献
7.
8.
F. Morits 《Mathematical Notes》1975,17(2):127-133
Let {Xi}
–
be a sequence of random variables, E(Xi) 0. If 1, estimates for the -th moments
can be derived from known estimates
of the -th moment. Here we generalized the Men'shov-Rademacher inequality for =2 for orthonormal Xi, to the case 1 and dependent random variables. The Men'shov-Payley inequality >2 for orthonormal Xi) is generalized for >2 to general random variables. A theorem is also proved that contains both the Erdös -Stechkin theorem and Serfling's theorem withv > 2 for dependent random variables.Translated from Matematicheskie Zametki, Vol. 17, No. 2, pp. 219–230, February, 1975.This article was written while the author was working in the V. A. Steklov Mathematics Institute, Academy of Sciences of the USSR. 相似文献
9.
10.
F. G. Abdullayev 《Czechoslovak Mathematical Journal》2001,51(3):643-660
Let C be the extended complex plane; G C a finite Jordan with 0 G; w= (z) the conformal mapping of G onto the disk
normalized by
. Let us set
, and let
be the generalized Bieberbach polynomial of degree n for the pair (G,0), which minimizes the integral
in the class of all polynomials of degree not exceeding n with
. In this paper we study the uniform convergence of the generalized Bieberbach polynomials
with interior and exterior zero angles and determine its dependence on the properties of boundary arcs and the degree of their tangency. 相似文献
11.
The Maurey–Rosenthal theorem states that each bounded and linear operator T from a quasi normed space E into some Lp()(0) which satisfies a vector-valued norm inequality
even allows a weighted norm inequality: there is a function 0wL
0() such that
Continuing the work of Garcia-Cuerva and Rubio de Francia we give several scalar and vector-valued variants of this fundamental result within the framework of quasi Köthe function spaces X() over measure spaces. They are all special cases of our main result (Theorem 2) which extends the Maurey–Rosenthal cycle of ideas to the case of homogeneous operators between vector spaces being homogeneously representable in quasi Köthe function spaces. 相似文献
12.
Adhemar Bultheel Pablo González-Vera Erik Hendriksen Olav Njåstad 《Acta Appl Math》2000,61(1-3):101-118
From the Erds–Turán theorem, it is known that if f is a continuous function on
and L
n
(f, z) denotes the unique Laurent polynomial interpolating f at the (2 n + 1)th roots of unity, then
Several years later, Walsh and Sharma produced similar result but taking into consideration a function analytic in
and continuous on
and making use of algebraic interpolating polynomials in the roots of unity.In this paper, the above results will be generalized in two directions. On the one hand, more general rational functions than polynomials or Laurent polynomials will be used as interpolants and, on the other hand, the interpolation points will be zeros of certain para-orthogonal functions with respect to a given measure on
. 相似文献
13.
Define the operator of Sunouchi
(f L
1) on the Walsh group with respect to the Walsh-Kaczmarz system. In this paper we prove that the operator T
is of weak type (1, 1), of type (H
1, L
1) and of type (p, p) for all 1 < p 2. 相似文献
14.
M. N. Sheremeta 《Mathematical Notes》1975,18(3):823-827
Suppose thatf(z) is an entire transcendental function with real Taylor coefficients, M(r)= max¦f(z)¦on¦z¦=r, and {n} is the sequence of sign changes of the coefficients. We will show that if (1/n)<, then
.Translated from Matematicheskie Zametki, Vol. 18, No. 3, pp. 395–402, September, 1975.The author thanks A. A. Gol'dberg for his useful comments. 相似文献
15.
O. L. Vinogradov 《Journal of Mathematical Sciences》2004,120(5):1662-1671
Let
be the Jacobi polynomials and let C[a,b] be the space of continuous functions on [a,b] with the uniform norm. In this paper, we study sequences of Lebesgue constants, i.e., of the norms of linear operators
generated by a multiplier matrix
defined by the following relations:
and
In the case || = || = 1/2, we prove the following statements for the Jacobi polynomials (these statements are similar to known results for the trigonometrical system). Consider the cases
and
Under some conditions on a function , the values
and
equal
and
In addition, we show that for the Fourier–Legendre summation methods ( = = 0) generated by the multiplier function
, the limit and supremum of the sequence of Lebesgue constants may differ. Bibliography: 11 titles. 相似文献
16.
Proper holomorphic mappings between generalized pseudoellipsoids 总被引:3,自引:0,他引:3
Gilberto Dini Angela Selvaggi Primicerio 《Annali di Matematica Pura ed Applicata》1991,158(1):219-229
Summary We characterize the existence of proper holomorphic mappings between pseudoellipsoids of the form
. If f:()() is any such mapping, the existence of a subgroup of Aut (()) such that
is shown equivalent to a condition on the branch locus of f. 相似文献
17.
Suppose z
1, z
2, ... z
n are complex numbers with absolute values more than 1 and Arg z
j Arg z
k for j k where Arg w stands for the argument of the complex number w in [0,2). In this note we show that
We also give necessary and sufficient conditions for equality in the above inequality. As an application, we improve the result of Govil and Labelle on Bernstein's inequality for some special polynomials. 相似文献
18.
On a Binary Diophantine Inequality Involving Prime Numbers 总被引:1,自引:0,他引:1
M. B. S. Laporta 《Acta Mathematica Hungarica》1999,83(3):179-187
Let 1 < c < 15/14 and N a sufficiently large real number. In this paper we prove that, for all (N, 2N\ A with
, the inequality
has solutions in primes
. 相似文献
19.
For f L
n
(T
d
) and
, the modulus of smoothness
is shown to be equivalent to
where T
n is the best trigonometric polynomial approximant of degree n to f in L
p and is the Laplacian. The above result is shown to be incorrect for 0 < p
. 相似文献
20.
In this paper we consider the weakly coupled elliptic system with critical growth
where a, b, c, d are C
1-functions defined in a bounded regular domain of
N
. Here we construct families of solutions which blow-up and concentrate at some points in as the positive parameter goes to zero.*The authors are supported by M.I.U.R., project Metodi variazionali e topologici nello studio di fenomeni non lineari. 相似文献