共查询到20条相似文献,搜索用时 31 毫秒
1.
The paper deals with the problem of recovering the parameters (functions)
and
of the Maxwell dynamical system
(tan is the tangent component;
is a solution) by the response operator
(
is the normal). The parameters determine the velocity
, the c-metric
, and the time
. It is shown that for any fixed
, the operator
determines
and
in
uniquely. Bibliography: 15 titles. 相似文献
2.
Introduce the notation:
, is the union of two segments [-1,1] and [-1 +
,1+
],
is a noninteger number,
is the Hölder class with exponent
on
The following result announced by the authors in [J. Math. Sci. 117 (2003), No. 3] is proved. There exist numbers a
1 (
) , b
1 (
)
0 depending only on
such that for any
there exists a polynomial
, such that
. Bibliography: 11 titles. 相似文献
3.
S. Ya. Novikov 《Journal of Mathematical Sciences》2004,120(5):1733-1751
We study operators
(not necessarily linear) defined on a quasi-Bahach space X and taking values in the space of real-valued Lebesgue-measurable functions. Factorization theorems for linear and superlinear operators with values in the space
are proved with the help of the Lorentz sequence spaces
. Sequences of functions belonging to fixed bounded sets in the spaces
are characterized for
and
. The possibility of distinguishing weak type operators (bounded in the space
) from operators factorizable through
is obtained in terms of sequences of independent random variables. A criterion under which an operator is symmetrically bounded in order in
, is established. Some refinements of the above-mentioned results are obtained for translation shift-invariant sets and operators. Bibliography: 30 titles. 相似文献
4.
Al Dababseh Avni Faez 《Ukrainian Mathematical Journal》2001,53(1):129-133
We prove that if G is a nonsingle-element n-ary finite group that belongs to a -closed formation
, then
, where
is the intersection of all maximal -closed subformations of the -closed formation of n-ary groups
. 相似文献
5.
An analog of the classical Fourier formula for the characteristic function of a convex compact set
is considered:
where W is a polyhedral in
. Bibliography: 6 titles. 相似文献
6.
D. E. Apushkinskaya H. Shahgholian N. N. Uraltseva 《Journal of Mathematical Sciences》2003,115(6):2720-2730
Let u and solve the problem
where is an open set in
0\} ,n \geqslant 2,H = \Delta - \partial _t \hfill \\ \hfill \\ \end{gathered} $$
" align="middle" border="0">
is the heat operator,
denotes the characteristic function of ,
is the unit cylinder in n+1,
, and the first equation is satisfied in the sense of distributions. We obtain the optimal regularity of the function u, i.e., we show that
. Bibliography: 6 titles. 相似文献
7.
Let {\bold x}[] be a stationary Gaussian process with zero mean and spectral density f, let
be the -algebra induced by the random variables {\bold x}[], D(R1), and let
t, t > 0, be the -algebra induced by the random variables x[],supp [-t,t]. Denote by
(f) the Gaussian measure on
generated by {\bold x}. Let
t(f) be the restriction of
(f) to
t. Let f and g be nonnegative functions such that the measures
t(f) and
t(g) are absolutely continuous. Put
For a fixed g(u) and for f(u)= ft(u) close to g(u) in some sense, the asymptotic normality of
t(f,g) is proved under some regularity conditions. Bibliography: 14 titles. 相似文献
8.
M. Bildhauer 《Journal of Mathematical Sciences》2003,115(6):2747-2752
Uniqueness is proved for solutions of the dual problem that is associated with the minimum problem
among the mappings
with prescribed Dirichlet boundary data and for smooth strictly convex integrands f of linear growth. No further assumptions on f or its conjugate function
are imposed, in particular,
is not assumed to be strictly convex. A special solution of the dual problem is seen to be a mapping into the image of
, which immediately implies uniqueness. Bibliography: 13 titles. 相似文献
9.
M. M. Roginskaya 《Journal of Mathematical Sciences》2001,107(4):4083-4091
A new collection of Riesz sets for
and
is exhibited. The results are new even in the one-dimensional case. The asymptotic estimate of Fourier multipliers on finite measures in the space
used in the proof is interesting in itself. Bibliography: 3 titles. 相似文献
10.
G. V. Kuz'mina 《Journal of Mathematical Sciences》2003,118(1):4880-4894
We apply a variant of the method of the extremal metric to some problems concerning extremal decompositions and related problems. Let
be a system of distinct points on
and let
be the family of all systems
of nonoverlapping simply connected domains on
such that
. Let
where
is the reduced module of the domain
with respect to the point
. At present, the problem concerning the value
was solved completely for
. In this work, we continue the previous author's investigations and consider the case
. In addition, we consider the problem concerning the maximum of the sum
in the family
introduced above, where
, are arbitrary points of the circle
, and is a positive number. We prove that if
, then the maximum is attained only for systems of equidistant points of the circle
. For
, this result was obtained earlier by Dubinin who applied the method of symmetrization. It is shown that if
, where
is an even number, then equidistant points of the circle
do not realize the indicated maximum. Bibliography: 11 titles. 相似文献
11.
Niels Jakob Laustsen 《K-Theory》2001,23(2):115-127
We prove that the K-groups of the Banach algebra
of bounded, linear operators on the pth James space
, where 1 < p < , are given by
and
. Moreover, for each Banach space
and each non-zero, closed ideal
contained in the ideal of inessential operators, we show that
and
. This enables us to calculate the K-groups of
for each Banach space
which is a direct sum of finitely many James spaces and
-spaces. 相似文献
12.
R. N. Karasev 《Journal of Mathematical Sciences》2001,104(4):1293-1300
Let
be a family of translations of a convex compact set
such that every two elements of
have a common point. Then there exist three points
such that each element of
contains one of these points. This answers in the affirmative an old question by Grünbaum. Bibliography: 13 titles. 相似文献
13.
In what follows, $C$ is the space of
-periodic continuous functions; P is a seminorm defined on C, shift-invariant, and majorized by the uniform norm;
is the mth modulus of continuity of a function f with step h and calculated with respect to P;
,
(
),
,
,
Theorem 1.
Let
. Then
For some values of
and seminorms related to best approximations by trigonometric polynomials and splines in the uniform and integral metrics, the inequalities are sharp. Bibliography: 6 titles. 相似文献
14.
E. G. Emelyanov 《Journal of Mathematical Sciences》2004,122(6):3648-3653
Let
be a finite Riemann surface. For a quadratic differential on
associated with a certain problem on extremal decomposition of
into n domains, a parametric family of quasiconformal mappings
, is defined. These mappings map the domains of the extremal decomposition of
onto the domains of the extremal decomposition of
.K This allows one to study the functional dependence of the problem on the parameters. Bibliography: 6 titles. 相似文献
15.
V.G. Osmolovskii 《Journal of Mathematical Sciences》2004,122(3):3278-3289
We consider the energy functional of a two-phase elastic medium
with quadratic energy densities
defined for
such that
,where
is a measurable characteristic function. Under some natural conditions on the data of the problem, we prove the existence of an interval (t
-,t
+) of the change of temperature
such that the energy functional has only a minimizer
such that
for
or
such that
t^ + $$
" align="middle" border="0">
. The energy functional has no minimizers
such that
or
if
. We derive two-sided estimates for the numbers
in terms of the characteristics of the two-phase elastic medium and the boundary condition. Bibliography: 3 titles. 相似文献
16.
O. M. Fomenko 《Journal of Mathematical Sciences》2003,118(1):4918-4932
Let
be the class number of properly equivalent primitive binary quadratic forms
of discriminant
. The case of indefinite forms
is considered. Assuming that the extended Riemann hypothesis for some fields of algebraic numbers holds, the following results are proved. 1. Let
be an arbitrarily slow monotonically increasing function such that
. Then
where
. 2. Let F be an arbitrary sufficiently large positive constant. Then for
x_F$$
" align="middle" border="0">
, the relation
holds. 3. The relation
holds, where A is Artin's constant. Hence, for the majority of discriminants of the form
, where
, the class numbers are small. This is consistent with the Gauss conjecture concerning the behavior of
for the majority of discriminants
0$$
" align="middle" border="0">
in the general case. Bibliography: 22 titles. 相似文献
(\log p)^{\alpha (p)} } \right\} = o(\pi (x)),$$ " align="middle" vspace="20%" border="0"> |
F} \right\} \asymp \frac{{\pi (x)}}{F}$$ " align="middle" vspace="20%" border="0"> |
17.
V. Zayachkovski 《Journal of Mathematical Sciences》1983,21(5):665-679
For the system of Euler equations and the incompressibility equation one considers the following initial-boundary value problem: the field of velocities
is prescribed at the initial moment and for all to one gives the following boundary conditions: on the entire boundary of the normal component of the velocity
is prescribed and on that part S1 of the boundary of where inflow occurs one prescribes the value of the velocity =rot
|S2, whose components satisfy a certain necessary equality, derived in the paper. For such a problem one proves its unique solvability on a small interval of time.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akad. Nauk SSSR, Vol. 96, pp. 39–56, 1980. 相似文献
18.
M. S. Lyapina 《Journal of Mathematical Sciences》2004,120(2):1109-1116
A bi-Lipschitz continuous mapping of a space X is a bijection
such that
, where
. We write
if f is a Lipschitz (bi-Lipschitz) mapping of X into itself and denote by
the set of all bi-Lipschitz mappings of X that are not isometry. Thus,
if
and blip
. For X we consider a standard Cantor set K on the real line (with standard metric). The main result of this paper is formulated as follows:
where
Bibliography: 2 titles. 相似文献
19.
L. Yu. Kolotilina 《Journal of Mathematical Sciences》2004,121(4):2465-2473
This paper studies irreducible matrices
, satisfying Brualdi's conditions
, or, shortly, Brualdi matrices. Here,
is the set of circuits of length
in the directed graph of A, and
is the support of
. Among the results obtained are a characterization of Brualdi matrices, implying, in particular, that they are generalized diagonally dominant; the necessary and sufficient conditions of singularity of Brualdi matrices; explicit expressions for the absolute values of the components of right null-vectors of a singular Brualdi matrix, and conditions necessary and sufficient for a boundary point of Brualdi's inclusion region to be an eigenvalue of an irreducible matrix. Bibliography: 8 titles. 相似文献
20.
An existence criterion for the Cesàro limit
of a bounded solution y(t) of the problem dy(t)/dt = Ay(t), y(0)=y0, t [O, ), where A is a closed linear operator with dense domain of definition D(A) in a reflexive Banach space E, is obtained under the condition that there exists a sufficiently small interval (O, ) belonging to the set of the regular points (A) of the operator A.Translated from Ukrayins'kyy Matematychnyy Zhurnal, Vol. 44, No. 9, pp. 1279–1280, September, 1992. 相似文献