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1.
This article improves results of Hamada, Helleseth and Maekawa on minihypers in projective spaces and linear codes meeting the Griesmer bound.In [10,12],it was shown that any
-minihyper, with
, where
, is the disjoint union of
points,
lines,...,
-dimensional subspaces. For q large, we improve on this result by increasing the upper bound on
non-square, to
non-square,
square,
, and (4) for
square, p prime, p<3, to
. In the case q non-square, the conclusion is the same as written above; the minihyper is the disjoint union of subspaces. When q is square however, the minihyper is either the disjoint union of subspaces, or the disjoint union of subspaces and one subgeometry
. For the coding-theoretical problem, our results classify the corresponding
codes meeting the Griesmer bound. 相似文献
2.
In this article, we consider the operator L defined by the differential expression
in L
2(–, ), where q is a complex valued function. Discussing the spectrum, we prove that L has a finite number of eigenvalues and spectral singularities, if the condition
holds. Later we investigate the properties of the principal functions corresponding to the eigenvalues and the spectral singularities. 相似文献
3.
Let
be the j-fold iterated function of
. Let
and > 0 be fixed, Q be a prime, and let N
k(Q|x) denote the number of those nx for which Q
. We give the asymptotics of N
k(Q|x) in the range
. 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.
With
, we here construct, for each positive integer N, a smooth function
of degree zero so that there must be at least N singular points for any map that minimizes the energy
in the family
. The infimum of over U(g) is strictly smaller than the infimum of over the continuous functions in U(g). There are some generalizations to higher dimensions.Research partially supported by the National Science FoundationResearch supported by an Alfred P. Sloan Graduate Fellowship 相似文献
6.
In [1--3] an extension of the solution of the equation
, to the singular set
, is defined in terms of the first integral. In this case all stationary points and all local extrema of the integral curve
such that the function
has a derivative at the extreme point belong to a set
, where Y is the line
. We study the local stability of local extrema of different types in the families of equations
small enough. Introduce the notation
. By abuse of language, we talk about the stability of local extrema when S is replaced with
. Some sufficient conditions for stability and instability are found. 相似文献
7.
Let u(x) xR
q
be a symmetric nonnegative definite function which is bounded outside of all neighborhoods of zero but which may have u(0)=. Let p
x, (·) be the density of an R
q
valued canonical normal random variable with mean x and variance and let {G
x, ; (x, )R
q
×[0,1 ]} be the mean zero Gaussian process with covariance
A finite positive measure on R
q
is said to be in
with respect to u, if
When
, a multiple Wick product chaos
is defined to be the limit in L
2, as 0, of
where
,
denotes the Wick product of the m
j
normal random variables
.Consider also the associated decoupled chaos processes
,
defined as the limit in L
2, as 0, of
where
are independent copies of G
x,.Define
Note that a neighborhood of the diagonals of
in
is excluded, except those points on the diagonal which originate in the same Wick product in (i). Set
One of the main results of this paper is:
Theorem A. If
is continuous on (R
q
)
r
for all
then
is continuous on
.When u satisfies some regularity conditions simple sufficient conditions are obtained for the continuity of
on (R
q
)
r
. Also several variants of (i) are considered and related to different types of decoupled processes. These results have applications in the study of intersections of Lévy process and continuous additive functionals of several Lévy processes. 相似文献
8.
Let S = x
1,...,x
n} be a finite subset of a partially ordered set P. Let f be an incidence function of P. Let
denote the n × n matrix having f evaluated at the meet
of x
i and x
j as its i, j-entry and
denote the n × n matrix having f evaluated at the join
of x
i and x
j as its i, j-entry. The set S is said to be meet-closed if
for all 1 i, j n. In this paper we get explicit combinatorial formulas for the determinants of matrices
and
on any meet-closed set S. We also obtain necessary and sufficient conditions for the matrices
and
on any meet-closed set S to be nonsingular. Finally, we give some number-theoretic applications. 相似文献
9.
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
10.
Let (x) = A(x)
, where A(x) denotes the number of square-full integers not exceeding x. In this paper, we prove that (x) = O
, which improves the exponent 4/27 obtained by Y.-C. Cai [5]. 相似文献
11.
Let
be a continuous semimartingale and let
be a continuous function of bounded variation. Setting
and
suppose that a continuous function
is given such that F is C1,2 on
and F is
on
. Then the following change-of-variable formula holds:
where
is the local time of X at the curve b given by
and
refers to the integration with respect to
. A version of the same formula derived for an Itô diffusion X under weaker conditions on F has found applications in free-boundary problems of optimal stopping. 相似文献
12.
The multidimensional Sparr interpolation method is implemented in the Besov spaces
and the Lizorkin--Triebel spaces
. It is shown that this results in Besov spaces of type
. An interpolation theorem for Besov spaces using weak conditions of the form
is formulated. 相似文献
13.
V. V. Kornienko 《Mathematical Notes》2000,68(5-6):576-587
We study the distribution in the complex plane
of the spectrum of the operator
, generated by the closure in
of the operation
originally defined on smooth functions
with values in a Hilbert space
satisfying the Dirichlet conditions
. Here
and A is a model operator acting in
. Criterial conditions on the parameter
for the eigenfunctions of the operator
to form a complete and minimal system as well as a Riesz basis in the Hilbert space H are given. 相似文献
14.
Mohan Namasivayam 《Annali di Matematica Pura ed Applicata》1986,144(1):157-172
Summary
Integral representations of junctions in the anisotropic Sobolev spaces
on unbounded domains are used in the study of the embeddings of these spaces into Lebesgue spaces. Estimates of entropy numbers of the embedding
are obtained, where k, p and q satisfy certain conditions and where is a certain type of quasibounded domain, 相似文献
15.
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
16.
S. Ya. Makhno 《Journal of Mathematical Sciences》1991,53(1):62-65
We study the behavior as 0 of the solution of the equation with periodic coefficients
相似文献
17.
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:
18.
G. Kuba 《Acta Mathematica Hungarica》2001,91(4):325-332
For a large real parameter t and 0 a b
we consider sums
where is the rounding error function, i.e. (z) = z - [z] - 1/2. We generalize Huxley's well known estimate
by showing that
holds uniformly in 0 a b
. Fruther, we investigate an analogous question related to the divisor problem and show that the inequality
, which (due to Huxley) holds uniformly in 0 a b
, and which is in general not true for 1 a b t, is true uniformly in 0 a b
. 相似文献
19.
Summary LetX be a diffusion in natural scale on (0,1], with 1 reflecting, and letc(x)(H
x
) andv(x)var (H
x
), whereH
x
=inf{t: X
t
=x}. Let
x
=sup{t:X
t
=x}. The main results of this paper are firstly that (i)c is slowly varying; (ii)
are all equivalent: and secondly that (v)
are all equivalent, and are implied by the condition
. Other partial results for more general limit theorems are proved, and new results on regular variation are established. 相似文献
20.
Moharram A. Khan 《Czechoslovak Mathematical Journal》2000,50(4):791-801
In this paper we investigate commutativity of rings with unity satisfying any one of the properties:
|