共查询到20条相似文献,搜索用时 46 毫秒
1.
B. Yousefi 《Czechoslovak Mathematical Journal》2004,54(1):261-266
Let
be a sequence of positive numbers and 1 p< . We consider the space H
p() of all power series
such that
. We investigate strict cyclicity of
the weakly closed algebra generated by the operator of multiplication by zacting on H
p(), and determine the maximal ideal space, the dual space and the reflexivity of the algebra
. We also give a necessary condition for a composition operator to be bounded on H
p() when
is strictly cyclic. 相似文献
2.
LetT be a contraction acting in a separable Hilbert space
and leaving invariant a nest
of subspaces of
. We answer the question: when doesT have an isometric extension to
which leaves invariant the nest
= {N N :N
;}. 相似文献
3.
Noboru Hamada 《Designs, Codes and Cryptography》1997,10(1):41-56
Let k and d be any integers such that k 4 and
. Then there exist two integers and in {0,1,2} such that
. The purpose of this paper is to prove that (1) in the case k 5 and (,) = (0,1), there exists a ternary
code meeting the Griesmer bound if and only if
and (2) in the case k 4 and (,) = (0,2) or (1,1), there is no ternary
code meeting the Griesmer bound for any integers k and d and (3) in the case k 5 and
, there is no projective ternary
code for any integers k and such that 1k-3, where
and
for any integer i 0. In the special case k=6, it follows from (1) that there is no ternary linear code with parameters [233,6,154] , [234,6,155] or [237,6,157] which are new results. 相似文献
4.
In normed spaces of functions analytic in the Jordan domain , we establish exact order estimates for the Kolmogorov widths of classes of functions that can be represented in by Cauchy-type integrals along = with densities f(·) such that
. Here, is a conformal mapping of
onto {w: |w| > 1}, and
is a certain subset of infinitely differentiable functions on T = {w: |w| = 1}. 相似文献
5.
E. P. Golubeva 《Journal of Mathematical Sciences》2003,118(1):4740-4752
Let h(d) be the class number of the field
and let
be the Lévy constant. A connection between these constants is studied. It is proved that if d is large, then the value h(d) increases, roughly speaking, at the rate
as
grows. A similar result is obtained in the case where the value
is close to
, i.e., to the least possible value. In addition, it is shown that the interval
contains no values of
for prime p such that p 3 (mod 4). As a corollary, a new criterion for the equality h(d)=1 is obtained. Bibliography: 14 titles. 相似文献
6.
Frank Marohn 《Extremes》2000,3(4):363-384
We consider the full statistical families of extreme value distributions
and generalized Pareto distributions
, where
, and
denote the shape, scale and location parameters, respectively. We consider the testing problems
against
and = 0 against 0, where and are treated as nuisance parameters. Showing local asymptotic normality (LAN), we derive asymptotic envelope power functions for test sequences and establish tests which attain these upper bounds. The finite sample size behavior is studied by simulations. 相似文献
7.
Dagmar Medková 《Czechoslovak Mathematical Journal》1997,47(4):651-679
The paper investigates the third boundary value problem
for the Laplace equation by the means of the potential theory. The solution is sought in the form of the Newtonian potential (1), (2), where is the unknown signed measure on the boundary. The boundary condition (4) is weakly characterized by a signed measure
the corresponding operator on the space of signed measures on the boundary of the investigated domain G. If there is 0 such that the essential spectral radius of
is smaller than || (for example, if G R
3 is a domain with a piecewise smooth boundary and the restriction of the Newtonian potential
on G is a finite continuous functions) then the third problem is uniquely solvable in the form of a single layer potential (1) with the only exception which occurs if we study the Neumann problem for a bounded domain. In this case the problem is solvable for the boundary condition
for which (G) = 0. 相似文献
8.
P. Cubiotti 《Journal of Optimization Theory and Applications》1997,92(3):457-475
In this paper, we deal with the following problem: given a real normed space E with topological dual E*, a closed convex set XE, two multifunctions :X2X and
, find
such that
We extend to the above problem a result established by Ricceri for the case (x)X, where in particular the multifunction is required only to satisfy the following very general assumption: each set (x) is nonempty, convex, and weakly-star compact, and for each yX–:X the set
is compactly closed. Our result also gives a partial affirmative answer to a conjecture raised by Ricceri himself. 相似文献
9.
We obtain the asymptotic behaviour for the L
norm of the first eigenfunction of the Dirichlet Laplace operator on a conic sector over a geodesic disc
in
as
. We are led to conjecture that for an open, bounded and convex set D with inradius and diameter d,
where
and
相似文献
10.
Summary In this paper, we continue earlier works of one of the authors on vague convergence of the sequence
k,n=
k+1 *...*
n, where
n is a sequence of probability measures on semigroups or groups. Typical results in this paper are: Theorem. Let S be a locally compact noncompact second countable group such that
being the support of a probability measure on S. Suppose there exists an open set V with compact closure such that x
–1
Vx=V for every xS. Then for all compact sets K, sup{
n
(Kx): xS0 as n. Theorem. Let S be an at most countable discrete group. Let
n be a sequence of probability measures on S. Then for all nonnegative integers k, the sequence
k,n converges vaguely to some probability measure if and only if there exists a finite subgroup G such that the series
and for any proper subgroup G of G and any choice of elements gn in S, the series
. A sufficient condition for the vague convergence of the sequence
k,n to a probability measure is that (i) there exists a finite subgroup G such that
and (ii)
n(e)>s>0 for all n, e being the identity.The author was supported by NSF grant MCS77-03639 相似文献
11.
Let (X
t
) be a one dimensional diffusion corresponding to the operator
, starting from x>0 and T
0 be the hitting time of 0. Consider the family of positive solutions of the equation
with (0, ), where
. We show that the distribution of the h-process induced by any such is
, for a suitable sequence of stopping times (S
M
: M0) related to which converges to with M. We also give analytical conditions for
, where
is the smallest point of increase of the spectral measure associated to
. 相似文献
12.
We discuss purely singular finite-rank perturbations of a self-adjoint operator A in a Hilbert space . The perturbed operators
are defined by the Krein resolvent formula
, Im z 0, where B
z are finite-rank operators such that dom B
z dom A = |0}. For an arbitrary system of orthonormal vectors
satisfying the condition span |
i
} dom A = |0} and an arbitrary collection of real numbers
, we construct an operator
that solves the eigenvalue problem
. We prove the uniqueness of
under the condition that rank B
z = n. 相似文献
13.
Zusammenfassung Es wird die Fortpflanzung elastisch-plastischer Spannungswellen in einem unendlichen Medium betrachtet, welches einer idealen Spannungs-Verformungs-Kurve folgt, Trescas Fliesskriterium unterworfen ist und einen sphärischen Hohlraum enthält, wobei an der Fläche des Hohlraumes ein Stoss
angenommen wird. Ein rechnerisches Verfahren, basiert auf endliche Differenzen, wird entwickelt and ein Beispiel gegeben.
Notation radial stress - tangential stress - K yield stress - rr non-dimensional radial stress ( /K) - non-dimensional tangential stress ( /K) - , Lame's constants - K b Bulk constant (=(3+2)/3) - v Poisson's constant - Material density - C Elastic wave velocity (=((+2)/)1/2) - C p Plastic wave velocity (=(K b /)1/2) - distance from center of cavity - r 0 cavity radius - v non-dimensional radial co-ordinate (= /r 0) - time - t non-dimensional time (=C /r 0) - radial displacement - u non-dimensional radial displacement (=/r 0) - particle velocity - v non-dimensional particle velocity (= /C) - pressure - P(t) non-dimensional pressure (= /K) 相似文献
Notation radial stress - tangential stress - K yield stress - rr non-dimensional radial stress ( /K) - non-dimensional tangential stress ( /K) - , Lame's constants - K b Bulk constant (=(3+2)/3) - v Poisson's constant - Material density - C Elastic wave velocity (=((+2)/)1/2) - C p Plastic wave velocity (=(K b /)1/2) - distance from center of cavity - r 0 cavity radius - v non-dimensional radial co-ordinate (= /r 0) - time - t non-dimensional time (=C /r 0) - radial displacement - u non-dimensional radial displacement (=/r 0) - particle velocity - v non-dimensional particle velocity (= /C) - pressure - P(t) non-dimensional pressure (= /K) 相似文献
14.
Peter Hellekalek 《Monatshefte für Mathematik》1980,90(4):291-295
Ifp2 is an integer, then every nonnegative integerk is represented by an expression of the form
with integersa
i
(k), 0a
i
(k)p–1,i=0.1,...,s. The radical-inverse function to the basep,
p
(k), is defined by
. The sequence
is uniformly distributed modulo 1 (it may be called a one-dimensional Halton sequence). In the casep=2 it is the van der Corput sequence. The set of all numbers (0, 1] such that the local discrepancy
is bounded inn is determined. 相似文献
15.
吴启光 《应用数学学报(英文版)》1995,11(4):378-388
QUADRATICESTIMATORSOFQUADRATICFUNCTIONSWITHPARAMETERSINNORMALLINEARMODELS¥WUQIGUANG(吴启光)(InstituteofSystemeScience,theChinese... 相似文献
16.
S. Yu. Orevkov 《Mathematical Notes》2000,68(5-6):588-593
Dehornoy constructed a right invariant order on the braid group B
n uniquely defined by the condition
1{\text{ if }}\beta _0 ,\beta _1$$
" align="middle" border="0">
are words in
. A braid is called strongly positive if
1$$
" align="middle" border="0">
for any
. In the present paper it is proved that the braid
is strongly positive if the word
does not contain
. We also provide a geometric proof of the result by Burckel and Laver that the standard generators of a braid group are strongly positive. Finally, we discuss relations between the right invariant order and quasipositivity. 相似文献
17.
Real valued M-estimators
in a statistical model 1 with observations
are replaced by
-valued M-estimators
in a new model with observations
where
are regressors,
is a structural parameter and
a structural function of the new model. Sufficient conditions for the consistency of
are derived, motivated by the sufficiency conditions for the simpler parent estimator
The result is a general method of consistent estimation in a class of nonlinear (pseudolinear) statistical problems. If F
has a natural exponential density ex–b( x ) then our pseudolinear model with u = (g o )–1 reduces to the well known generalized linear model, provided () = db()/d and g is the so-called link function of the generalized linear model. General results are illustrated for special pairs and leading to some classical M-estimators of mathematical statistics, as well as to a new class of generalized -quantile estimators. 相似文献
18.
Summary Let (,,P) be a probability space and let {itX
n
()}
n=1 be a sequence of i.i.d. random vectors whose state space isZ
m for some positive integerm, where Z denotes the integers. Forn = 1, 2,... letS
n
() be the random walk defined by
. ForxZ
m andU
m, them-dimensional torus, let
. Finally let
be the characteristic function of the X's.In this paper we show that, under mild restrictions, there exists a set withP{
0
} = 1 such that for
0 we have
for all aU
m,le0.As a consequence of this theorem, we obtain two corollaries. One is concerned with occupancy sets form-dimensional random walks, and the other is a mean ergodic theorem.Research supported by N.S.F. Grant # MCS 77-26809 相似文献
19.
We study the asymptotic behaviour ast tends to + of the solution of (u/t)–Lu+(u)–0,u
|=0 whereL is a second order self-adjoint elliptic operator and a maximal monotone graph of . If |(r)|/|r|2L
1 (-1, 1) and 1 is the first eigenvalue ofL we prove that
u(.,t) converges uniformly on
to some element of Ker (L + 1
I) and that the limit is nonzero if |(r)|/|r| is nondecreasing. We give also some properties of the limit (monotonicity, continuity, range). 相似文献
20.
The following theorem is proved. Let {
k(t)} be an arbitrary complete orthonormal system on [0, 1] and let 1/2<<1. Then anf(t) C exists for all< such that
k=1
· |ck(f)|p=, p=2/(l+2), where
.Translated from Matematicheskie Zametki, Vol. 6, No. 5, pp. 567–572, November, 1969.The authors wish to thank P. P. Zabreiko and P. L. Ul'yanov for helpful discussions and remarks. 相似文献