共查询到20条相似文献,搜索用时 78 毫秒
1.
Shiquan WU 《应用数学学报(英文版)》1996,12(4):377-383
Letn, s
1,s
2, ... ands
n
be positive integers. Assume
is an integer for eachi}. For
,
, and
, denotes
p
(a)={j|1jn,a
j
p},
, and
.
is called anI
t
p
-intersecting family if, for any a,b
,a
i
b
i
=min(a
i
,b
i
)p for at leastt i's.
is called a greedyI
t
P
-intersecting family if
is anI
t
p
-intersecting family andW
p
(A)W
p
(B+A
c
) for anyAS
p
(
) and any
with |B|=t–1.In this paper, we obtain a sharp upper bound of |
| for greedyI
t
p
-intersecting families in
for the case 2ps
i
(1in) ands
1>s
2>...>s
n
.This project is partially supported by the National Natural Science Foundation of China (No.19401008) and by Postdoctoral Science Foundation of China. 相似文献
2.
El-B. Yallaoui 《Periodica Mathematica Hungarica》1991,23(2):109-120
Let X be an abstract set and L a lattice of subsets of X. To each lattice regular measure µ, we associate two induced measures
and
on suitable lattices of the Wallman space IR(L) and another measure µ on the spaceIR(L). We will investigate the reflection of smoothness properties of p onto
,
and µ; and try to set some new criterion for repleteness and measure repleteness. 相似文献
3.
T. Simon 《Journal of Theoretical Probability》2004,17(4):979-1002
Let Z
t
, t 0 be a strictly stable process on
with index (0, 2]. We prove that for every p > , there exists = , p
and
such that
where || Z||
p
stands for the strong p-variation of Z on [0,1]. The critical exponent p
, takes a different shape according as | Z| is a subordinator and p > 1, or not. The small ball constant
is explicitly computed when p > 1, and a lower bound on
is easily obtained in the general case. In the symmetric case and when p > 2, we can also give an upper bound on
in terms of the Brownian small ball constant under the (1/p)-Höder semi-norm. Along the way, we remark that the positive random variable
is not necessarily stable when p > 1, which gives a negative answer to an old question of P. E. Greenwood.10 相似文献
4.
A. N. Bakhvalov 《Analysis Mathematica》2001,27(1):3-36
Let a ={nlna (n+1)}, where a R. The following results are established: For every &fnof a BV ((- ]2), the triangular partial sums of its Fourier series are uniformly bounded if a = -1, and converge everywhere if a < -1.For every a>0, there exists &fnof a BV ((- ]2) such that the triangular partial sums of its Fourier series are unbounded at the point (0;0). 相似文献
5.
Matthew R. Brown 《Journal of Algebraic Combinatorics》2002,15(2):107-125
If a GQ S of order (s, s) is contained in a GQ S of order (s, s
2) as a subquadrangle, then for each point X of S\S the set of points
of S collinear with X form an ovoid of S. Thas and Payne proved that if S=
(4,q),q even, and
is an elliptic quadric for each XS\S,thenS
(5,q). In this paper we provide a single proof for the q odd and q even cases by establishing a link between the geometry involved and the first cohomology group of a related simplicial complex. 相似文献
6.
Alan S. McRae 《Geometriae Dedicata》2001,84(1-3):321-330
If denotes the curvature and the torsion of a closed, generic, and oriented polygonal space curve X in
, then we show that
X
(2 + 2) ds =
X
ds +
X
| | ds > 4 if is positive. We also show that
X
(2 + 2) ds 2n if no four consecutive vertices lie in a plane and X has linking number n with a straight line. These extend theorems of Milnor and Totaro. 相似文献
7.
Mervyn J. Silvapulle Pranab K. Sen 《Annals of the Institute of Statistical Mathematics》1993,45(1):159-171
Consider the linear modelY=X+E in the usual matrix notation where the errors are independent and identically distributed. We develop robust tests for a large class of one- and two-sided hypotheses about when the data are obtained and tests are carried out according to a group sequential design. To illustrate the nature of the main results, let
and
be anM- and the least squares estimator of respectively which are asymptotically normal about with covariance matrices 2(X
t
X)–1 and 2(X
t
X)–1 respectively. Let the Wald-type statistics based on
and
be denoted byRW andW respectively. It is shown thatRW andW have the same asymptotic null distributions; here the limit is taken with the number of groups fixed but the numbers of observations in the groups increase proportionately. Our main result is that the asymptotic Pitman efficiency ofRW relative toW is (2/2). Thus, the asymptotic efficiency-robustness properties of
relative to
translate to asymptotic power-robustness ofRW relative toW. Clearly, this is an attractive result since we already have a large literature which shows that
is efficiency-robust compared to
. The results of a simulation study show that with realistic sample sizes,RW is likely to have almost as much power asW for normal errors, and substantially more power if the errors have long tails. The simulation results also illustrate the advantages of group sequential designs compared to a fixed sample design, in terms of sample size requirements to achieve a specified power. 相似文献
8.
Horst Elmar Winkelnkemper 《Annals of Global Analysis and Geometry》1992,10(3):209-218
Let
t
be the flow (parametrized with respect to arc length) of a smooth unit vector field v on a closed Riemannian manifold M
n
, whose orbits are geodesics. Then the (n-1)-plane field normal to v, v, is invariant under d
t
and, for each x M, we define a smooth real function
x
(t) : (1 +
i
(t)), where the i(t) are the eigenvalues of AA
T, A being the matrix (with respect to orthonormal bases) of the non-singular linear map d2t
, restricted to v at the point x
-t M
n.Among other things, we prove the
Theorem (Theorem II, below). Assume v is also volume preserving and that
x
'
(t) 0 for all x M and real t; then, if
x
t
: M M is weakly missng for some t, it is necessary that vx 0 at all x M. 相似文献
9.
Summary We examine the problem:u+a(x)u–b(x)u=f(x) for 0<x<1,a(x)>0,b(x)>,
2
= 4>0,a, b andf inC
2 [0, 1], in (0, 1],u(0) andu(1) given. Using finite elements and a discretized Green's function, we show that the El-Mistikawy and Werle difference scheme on an equidistant mesh of widthh is uniformly second order accurate for this problem (i.e., the nodal errors are bounded byCh
2, whereC is independent ofh and ). With a natural choice of trial functions, uniform first order accuracy is obtained in theL
(0, 1) norm. On choosing piecewise linear trial functions (hat functions), uniform first order accuracy is obtained in theL
1 (0, 1) norm. 相似文献
10.
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
11.
Dynamical systems of the form
,u(0)=u
0, where,B is a densely defined linear operator mapping its domainD (B
) into — the infinitesimal generator of a semigroup of operatorsT (t, B) of classC
0 — are investigated, such that for each solutionu to
, whereP is the spectral eigenprojection onto the null space ofB.It is shown that under some general hypotheses concerning spectral properties ofB the above stability condition is equivalent with the following situation: There exist (i) a normal generating coneK such thatT(t;B)KK fort0 and (ii) a strictly positive element
in the dual coneK such that
, whereB denotes the dual ofB. Condition (ii) implies the so called total concentration time preservation, i. e.
. 相似文献
12.
S. A. Kruglyak V. I. Rabanovich Yu. S. Samoilenko 《Functional Analysis and Its Applications》2002,36(3):182-195
In the paper, for all n, we describe the set n of all real numbers admitting a collection of projections P
1,...,P
n on a Hilbert space H such that k=1
n
P
k= I (I is the identity operator on H) and study the problem to find all collections of this kind for a given
n
. 相似文献
13.
Yosio Mutō 《Geometriae Dedicata》1981,11(1):1-18
In a previous paper [4] the present author studied a C
mapping
where M is an m-dimensional C
manifold, I is some interval and for each tI the mapping
is an immersion satisfying the following conditions, (i) The Gauss map associated with the immersion is regular. (ii) The Gauss image of the immersed submanifold is fixed against t for each point p of M. Such a mapping
was called an admissible deformation. The purpose of the present paper is to give results obtained since then. 相似文献
14.
Michel Weber 《Journal of Theoretical Probability》1996,9(1):105-112
Let (Y,,,T) be an ergodic dynamical system. LetA be an nonempty subset ofL
2() such that
, whereA=sup{||sȒt||2
,s, tA} andN(A, u) is the smallest number ofL
2()-open balls of radiusu, centered inA, enough to coverA. Let
. We prove as a consequence of a more general result, thatC(A) is aGB subset ofL
2(). 相似文献
15.
Let X be an open subset of
n and (f1, ...,fp): X
p be a holomorphic mapping. We prove that if (x0,0, 0) T* ×
p does not belong to the characteristic variety of the
X []-module
X[]f, then there exists a conic neighborhood V × of (x0, 0) such the function
is rapidely decreasing in | Im | for with Re bounded, for any (n,n)-form of class C with compact support in V. The following partial converse of this result is also established: if
for all (n,n)-forms of class C with compact support in X, then
. 相似文献
16.
Michael Lin 《Probability Theory and Related Fields》1981,55(2):231-236
Summary Let P be a Markov operator on L
(X, , m). Theorem 1: (i) P is weakly mixing (ii) For every fL
there is a sequence {nt} of density 1 such that all w
*-cluster points of
are constants (iii) For every fL
there is a {kj} with
w
*-convergent to a constant. Theorem 2: If P is induced by a non-singular transformation , P is weakly mixing For every A, {
–n(A)} has a remotely trivial subsequence. The existence of a finite invariant measure is not required in these results. 相似文献
17.
Bernard Krötz 《Compositio Mathematica》2001,125(2):155-191
If G is a semisimple Lie group and (,
) an irreducible unitary representation of G with square integrable matrix coefficients, then there exists a number d() such that
The constant d() is called the formal dimension of (,
) and was computed by Harish-Chandra in [HC56, 66]. If now HG is a semisimple symmetric space and (,
) an irreducible H-spherical unitary (,
) belonging to the holomorphic discrete series of HG, then one can define a formal dimension d() in an analogous manner. In this paper we compute d() for these classes of representations. 相似文献
18.
E. Bolthausen 《Probability Theory and Related Fields》1982,60(3):283-289
Summary Let 0, 1,... be a stationary Harris recurrent Markov chain with state space (E,), and let f E IR, X
i=f(i). It is known that the sequence X
i, i0, is strongly mixing, i.e. (n)>0 where (n) are the strong (or Rosenblatt) mixing coefficients. If (n) decreases at a sufficiently fast rate and f is suitable, then a central limit holds for the partial sums
. The present paper gives conditions in order that the convergence rates are O(n
–1/2). 相似文献
19.
Pavel Valtr 《Discrete and Computational Geometry》1992,7(1):135-152
For a finite setA of points in the plane, letq(A) denote the ratio of the maximum distance of any pair of points ofA to the minimum distance of any pair of points ofA. Fork>0 letc
(k) denote the largest integerc such that any setA ofk points in general position in the plane, satisfying
for fixed
, contains at leastc convex independent points. We determine the exact asymptotic behavior ofc
(k), proving that there are two positive constants=(), such thatk
1/3c
(k)k
1/3. To establish the upper bound ofc
(k) we construct a set, which also solves (affirmatively) the problem of Alonet al. [1] about the existence of a setA ofk points in general position without a 7-hole (i.e., vertices of a convex 7-gon containing no other points fromA), satisfying
. The construction uses Horton sets, which generalize sets without 7-holes constructed by Horton and which have some interesting properties. 相似文献
20.
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