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1.
Let K, D be centrally symmetric convex bodies in
Let k < n and let dk(K, D) be the smallest Banach–Mazur distance between k-dimensional sections of K and D. Define
where the supremum is taken over all n-dimensional convex symmetric bodies K, D. We prove that, for any k < n,
where
means that
for some absolute constants C, a > 0. 相似文献
2.
E. G. Emelyanov 《Journal of Mathematical Sciences》2004,122(6):3641-3647
A sharp estimate of the product
(as usual, R(D,b) denotes the conformal radius of a domain D with respect to a point b D) in the family of all quadruples of nonoverlapping simply connected domains {Dk},bk Dk,k=1,...,4, is obtained. Here, {b1,...,b4} are four arbitrary distinct points on
is an arbitrary positive number. The proof involves the solution of the problem on maximizing a certain conformal invariant, which is related to the problem under consideration. Bibliography: 5 titles. 相似文献
3.
Let = (1,...,d) be a vector with positive components and let D be the corresponding mixed derivative (of order j with respect to the jth variable). In the case where d > 1 and 0 < k < r are arbitrary, we prove that
and
for all
Moreover, if
is the least possible value of the exponent in this inequality, then
Deceased.Translated from Ukrainskyi Matematychnyi Zhurnal, Vol. 56, No. 5, pp. 579–594, May, 2004. 相似文献
4.
Let
be sequences of real numbers which are symmetric in k. Let
be independent sequences of independent normal random variables with mean zero and variance one. For each fixed choice of
we consider
Let
Several examples are given in which the condition
is either a sufficient, a necessary, or a necessary and sufficient condition for {Q(x), x[0, 2]
n
} to have a continuous version. 相似文献
5.
Anastasios D. Simalarides 《Periodica Mathematica Hungarica》2000,40(1):71-75
Let be a primitive character mod k, k > 2. In [1], the following elementary estimate
was given, where
by definition. In the present note we sharpen this estimate by a factor 3/4 in the case of an even primitive character , by improving upon the proof given in [1] in a way which does not alter the elementary character of the method. 相似文献
6.
For a trigonometric series
defined on [−π, π)
m
, where V is a certain polyhedron in R
m
, we prove that
if the coefficients a
k
satisfy the following Sidon-Telyakovskii-type conditions:
Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, No. 5, pp. 579–585, May, 2008. 相似文献
7.
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
8.
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
9.
K. Yoneda 《Acta Mathematica Hungarica》1999,83(4):327-338
When E is a closed set of measure zero in the dyadic group and the Walsh series
satisfies
, then for some c > 0,
Consequently any control function of the a.e. convergence is not L/(log+ L)-integrable. 相似文献
10.
Emmanuel Peyre 《K-Theory》1998,15(2):99-145
The central result of this paper is the following generalization of a result of the author on products of Severi–Brauer varieties. Let G be a semi-simple linear algebraic group over a field k. Let V be a generalized flag variety under G. Then there exist finite extensions ki of k for 1im, elements i in Br ki and a natural exact sequence
Ker
. After giving a more explicit expression of the second morphism in a particular case, we apply this result to get classes in H
which are k-negligible for any field k of characteristic different from 2 which contains a fourth root of unity, for a group Q which is a central extension of an F2 vector space by another. 相似文献
11.
We obtain new unimprovable Kolmogorov-type inequalities for differentiable periodic functions. In particular, we prove that, for r = 2, k = 1 or r = 3, k = 1, 2 and arbitrary q, p [1, ], the following unimprovable inequality holds for functions
:
where
and
r
is the perfect Euler spline of order r. 相似文献
12.
Vincent Borrelli Fabiano Brito Olga Gil-Medrano 《Annals of Global Analysis and Geometry》2003,23(2):129-140
We construct a one-parameter family of unit smooth vector fieldsglobally defined on the sphere
2k+1 for k 2, with energyconverging to the energy of the unit radial vector field, which isdefined on the complementary of two antipodal points. So we prove thatthe infimum of the energy of globally defined unit smooth vector fieldsis
相似文献
13.
Let β
0=0.308443… denote the Littlewood-Salem-Izumi number, i.e., the unique solution of the equation
In this paper it is proved that if a
0≥a
1≥⋅⋅⋅≥a
n
>0 and
, k≥1 then for all θ∈(0,π)
and furthermore, the number β
0 is best possible in the sense that for any β∈(0,β
0)
where the coefficients c
k
(β) are defined as
Results for the sine sums are obtained as well.
These results generalize and sharpen the well known trigonometric inequalities of Vietoris.
This research was supported by a grant from the Australian Research Council. The second author was also supported in part
by the NSERC Canada under grant G121211001. The third author was also supported in part by the NSFC of China under grant 10471010. 相似文献
14.
We investigate the relationship between the constants K(R) and K(T), where
is the exact constant in the Kolmogorov inequality, R is the real axis, T is a unit circle,
is the set of functions x L
p(G) such that x
(r) L
s(G), q, p, s [1, ], k, r N, k < r, We prove that if
thenK(R) = K(T),but if
thenK(R) K(T); moreover, the last inequality can be an equality as well as a strict inequality. As a corollary, we obtain new exact Kolmogorov-type inequalities on the real axis. 相似文献
15.
Xia Chen 《Journal of Theoretical Probability》1999,12(2):421-445
Let {X
n
}
n0 be a Harris recurrent Markov chain with state space E, transition probability P(x, A) and invariant measure , and let f be a real measurable function on E. We prove that with probability one,
under some best possible conditions. 相似文献
16.
O. L. Vinogradov 《Journal of Mathematical Sciences》2002,110(5):2944-2954
Let C[-1,1] be the space of continuous functions f:[-1,1] with the uniform norm, let
Pk
be the Legendre polynomials such that
Pk
(1)=1, and let
J0
be the Bessel function of zero index. We consider sequences of linear operators (summation methods)
Un:C
[-1,1] C[-1,1] defined by a multiplier function as follows:
The values
, the norms of the operators
Un
, are called the Lebesgue constants of a summation method. The main result of this paper is the following statement. If a function is continuous on [\0,+),
is the FourierBessel transform of , and the function
is summable on [\0,+) for some q>1, then
Bibliography: 8 titles. 相似文献
17.
Ram U. Verma 《Journal of Computational Analysis and Applications》2002,4(3):177-192
Consider the convergence of the projection methods based on an extension of a special class of algorithms for the approximation--solvability of the following class of nonlinear quasivariational inequality (NQVI) problems: find an element
such that
and
where
are mappings on H and K is a nonempty closed convex subset of a real Hilbert space H. The iterative procedure is characterized as a nonlinear quasivariational inequality: for any arbitrarily chosen initial point x
0 K and, for constants
0$$
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and
0$$
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, we have
where
This nonlinear quasivariational inequality type algorithm has an equivalent projection formula
where
for the projection P
K
of H onto K. 相似文献
18.
O. N. Litvin 《Ukrainian Mathematical Journal》1992,44(11):1378-1384
A general algorithm is proposed for constructing interlineation operators
, x=(x1, x2) with the properties
相似文献
19.
Let
be realhomogeneous functions in
ofdegree
and let bethe Borel measure on
given by
20.
O. M. Fomenko 《Journal of Mathematical Sciences》2003,118(1):4910-4917
Let
be the Hecke eigenbasis of the space
of
-cusp forms of weight 2. Let p be a prime. Let
be the Hecke L-series of form
. The following statements are proved:
|