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1.
Given a polynomial , we calculate a subspace Gp of the linear space 〈X〉 generated by the indeterminates which is minimal with respect to the property (the algebra generated by Gp, and prove its uniqueness. Furthermore, we use this result to characterize the pairs (P,Q) of polynomials P(X1,…,Xn) and Q(X1,…,Xn) for which there exists an isomorphism T:〈X〉 →〈X〉 that “separates P from Q,” i.e., such that for some k(1<k<n) we can write P and Q as and respectively, where . 相似文献
2.
Let , let , where g2 and g3 are coefficients of the elliptic curve: Y2 = 4X3 ? g2X ? g3 over a finite field and Δ = g23 ? 27g32 and let . Then the p-adic cohomology theory will be applied to compute explicitly the zeta matrices of the elliptic curves, induced by the pth power map on the free -module . Main results are; Theorem 1.1: X2dY and YdX are basis elements for ; Theorem 1.2: YdX, X2dY, Y?1dX, Y?2dX and XY?2dX are basis elements for , where is a lifting of X, and all the necessary recursive formulas for this explicit computation are given. 相似文献
3.
Sidney I. Resnick 《Stochastic Processes and their Applications》1973,1(1):67-82
{Xn,n?1} are i.i.d. random variables with continuous d.f. F(x). Xj is a record value of this sequence if Xj>max{X1,…,Xj?1}. Consider the sequence of such record values {XLn,n?1}. Set R(x)=-log(1?F(x)). There exist Bn > 0 such that . in probability (i.p.) iff i.p. iff → ∞ as x→∞ for all k>1. Similar criteria hold for the existence of constants An such that XLn?An → 0 i.p. Limiting record value distributions are of the form N(-log(-logG(x))) where G(·) is an extreme value distribution and N(·) is the standard normal distribution. Domain of attraction criteria for each of the three types of limit laws can be derived by appealing to a duality theorem relating the limiting record value distributions to the extreme value distributions. Repeated use is made of the following lemma: If , then XLn=Y0+…+Yn where the Yj's are i.i.d. and . 相似文献
4.
A completely regular space X is called nearly pseudocompact if υX?X is dense in βX?X, where βX is the Stone-?ech compactification of X and υX is its Hewitt realcompactification. After characterizing nearly pseudocompact spaces in a variety of ways, we show that X is nearly pseudocompact if it has a dense locally compact pseudocompact subspace, or if no point of X has a closed realcompact neighborhood. Moreover, every nearly pseudocompact space X is the union of two regular closed subsets X1, X2 such that Int X1 is locally compact, no points of X2 has a closed realcompact neighborhood, and . It follows that a product of two nearly pseudocompact spaces, one of which is locally compact, is also nearly pseudocompact. 相似文献
5.
C.G Khatri 《Journal of multivariate analysis》1978,8(3):453-467
Optimization problems are connected with maximization of three functions, namely, geometric mean, arithmetic mean and harmonic mean of the eigenvalues of (X′ΣX)?1ΣY(Y′ΣY)?1Y′ΣX, where Σ is positive definite, X and Y are p × r and p × s matrices of ranks r and s (≥r), respectively, and X′Y = 0. Some interpretations of these functions are given. It is shown that the maximum values of these functions are obtained at the same point given by X = (h1 + ?1hp, …, hr + ?rhp?r+1) and , where h1, …, hp are the eigenvectors of Σ corresponding to the eigenvalues λ1 ≥ λ2 ≥ … ≥ λp > 0, ?j = +1 or ?1 for j = 1,2,…, r and , are linear functions of hr+1,…, hp?r. These results are extended to intermediate stationary values. They are utilized in obtaining the inequalities for canonical correlations θ1,…,θr and they are given by expressions (3.8)–(3.10). Further, some new union-intersection test procedures for testing the sphericity hypothesis are given through test statistics (3.11)–(3.13). 相似文献
6.
K.B. Athreya 《Statistics & probability letters》1983,1(3):147-150
Let X1, X2, X3, … be i.i.d. r.v. with E|X1| < ∞, E X1 = μ. Given a realization X = (X1,X2,…) and integers n and m, construct Yn,i, i = 1, 2, …, m as i.i.d. r.v. with conditional distribution for 1 ? j ? n. ( denotes conditional distribution given X). Conditions relating the growth rate of m with n and the moments of X1 are given to ensure the almost sure convergence of toμ. This equation is of some relevance in the theory of Bootstrap as developed by Efron (1979) and Bickel and Freedman (1981). 相似文献
7.
Joachim Schröder 《Topology and its Applications》1983,16(3):237-241
It is shown that the category of Urysohn spaces and continuous maps is not cowellpowered. To this end we will construct for each ordinal number β a Urysohn space Yβ with card and a continuous map from the rationals into Yβ. It turns out that is an external monomorphism in the category of Hausdorff spaces and an epimorphism in the category of Urysohn spaces. 相似文献
8.
Estimation d'une rupture en dépendance faibleChange point estimation for a weakly dependent sequence
Let be a stationary sequence governed by the model Yn=m(Xn)+σ(Xn)εn where is i.i.d. and independent from The latter sequence satisfy a weak dependence condition proposed by Doukhan and Louhichi in [2]. We provide a Central Limit Theorem for jumps in the regression function. Our method deals with linear local regression described in [4]. We use a variation on Lindeberg–Rio method as in [5]. To cite this article: P. Ango Nze, C. Prieur, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 267–270. 相似文献
9.
Hans G. Feichtinger 《Journal of Mathematical Analysis and Applications》1984,102(2):289-327
It is shown that for a comprehensive family of translation invariant Banach spaces (B, ∥ ∥B) of (classes of) measurable functions or distributions on a locally compact group (including most of the spaces of interest in harmonic analysis) the following compactness criterion generalizing the well-known results due to Kolmogorov-Riesz-Weil concerning compact sets in Lp(G), 1 ? p < ∞, holds true: A closed subset M ? B is compact in B if and only if it satisfies the following conditions: (a) sup? ? M ∥?∥B < ∞; (b) for all ; (c) for all . Among various applications a characterization of the space of all compact multipliers between suitable pairs of such spaces can be derived. 相似文献
10.
Roger Howe 《Journal of Functional Analysis》1979,32(3):297-303
Let (i, H, E) and (j, K, F) be abstract Wiener spaces and let α be a reasonable norm on E ? F. We are interested in the following problem: is () an abstract Wiener space ? The first thing we do is to prove that the setting of the problem is meaningfull: namely, i ? j is always a continuous one to one map from into . Then we exhibit an example which shows that the answer cannot be positive in full generality. Finally we prove that if F=Lp(X,,λ) for some σ-finite measure λ ? 0 then (X,,λ) is an abstract Wiener space. By-products are some new results on γ-radonifying operators, and new examples of Banach spaces and cross norms for which the answer is affirmative (in particular α = π the projective norm, and F=L1(X,,λ)). 相似文献
11.
David S Jerison 《Journal of Functional Analysis》1981,43(1):97-142
For (x,y,t)∈n × n × , denote and . When α = n ? 2q, a represents the action of the Kohn Laplacian □b on q-forms on the Heisenberg group. For ?n < α < n, we construct a parametrix for the Dirichlet problem in smooth domains D near non-characteristic points of ?D. A point w of ?D is non-characteristic if one of X1,…, Xn, Y1,…, Yn is transverse to ?D at w. This yields sharp local estimates in the Dirichlet problem in the appropriate non-isotropic Lipschitz classes. The main new tool is a “convolution calculus” of pseudo-differential operators that can be applied to the relevant layer potentials, for which the usual asymptotic composition formula is false. Characteristic points are treated in Part II. 相似文献
12.
The Fréchet distance between two multivariate normal distributions having means μX, μY and covariance matrices ΣX, ΣY is shown to be given by . The quantity d0 given by is a natural metric on the space of real covariance matrices of given order. 相似文献
13.
Allan R Sampson 《Statistics & probability letters》1984,2(2):77-81
A multivariate correlation ratio of a random vector upon a random vector is defined by where Λ, a fixed positive definite matrix, is related to the relative importance of predictability for the entries of . The properties of ηΛ are discussed, with particular attention paid to a ‘correlation-maximizing’ property. Given are applications of ηΛ to the elliptically symmetric family of distributions and the multinomial distribution. Also discussed is the problem of finding those r linear functions of that are most predictable (in a correlation ratio sense) from . 相似文献
14.
Derek W Robinson 《Journal of Functional Analysis》1977,24(3):280-290
Let U, V be two strongly continuous one-parameter groups of bounded operators on a Banach space with corresponding infinitesimal generators S, T. We prove the following: ∥Ut, ? Vt ∥ = O(t), t → 0, if and only if U = V; ∥Ut ? Vt∥ = O(tα), t → 0; with 0 ? α ? 1, if and only if , where Ω, P, are bounded operators on such that if and only if has a bounded extension to 1. Further results of this nature are inferred for semigroups, reflexive spaces, Hilbert spaces, and von Neumann algebras. 相似文献
15.
Let and denote respectively the space of n×n complex matrices and the real space of n×n hermitian matrices. Let p,q,n be positive integers such that p?q?n. For , the (p,q)-numerical range of A is the set , where Cp(X) is the pth compound matrix of X, and Jq is the matrix Iq?On-q. Let denote n or . The problem of determining all linear operators T: → such that is treated in this paper. 相似文献
16.
J.G. Besjes 《Journal of Mathematical Analysis and Applications》1974,48(2):594-609
We consider the first initial-boundary value problem for and L1 are linear elliptic partial differential operators) and investigate the properties of u(x, t, ?) as ? ↓ 0 in the maximum norm. Special attention is paid to approximations obtained by the boundary layer method. We use a priori estimates. 相似文献
17.
We study the question: given a morphism in the category pro-(Poi nted. Homotopy) where the domain and range are inverse sequences of well-pointed CW complexes, and given that ? induces an isomorphism {Xn}→{Yn} in pro-(Homotopy), what additional hypotheses force ? to be an isomorphism in pro-(Pointed Homotopy)? Conjecture. If the dimensions of the Yn's are bounded, then ? is an isomorphism in pro-(Pointed Homotopy). We first prove the special case of this conjecture in which dim Yn?d<∞ for all n, and , Yn being the universal cover of Yn. Then we deal with the general case: we show that there are certain elements of each π1Yn with the properties: (i) these elements commute if and only if ? is an isomorphism in pro-(Pointed Homotopy); (ii) if dim Yn?d<∞ for all n, then powers of these elements commute. While (i) and (ii) are not incompatible, this result puts severe restrictions on the nature of any possible counter-example to the conjecture.Our method also gives pro-homotopy analogues of the well-known fact that if a K(π, 1) is N-dimensional, then π is torsion-free and contains no abelian subgroup of rank>N. The latter theorems apply to inverse sequences {Yn} of CW complexes where dim Yn is finite but not necessarily bounded, hence in particular to infinite-dimensional shape-aspherical compacta. 相似文献
18.
Let be the injective tensor product of the separable Banach spaces X and Y and let SX, SY and be the unit spheres of these spaces. The tensor product of two symmetric finite measures η1 on SX and η2 on SY, η1?η2, is defined in a natural way as a measure on . It is shown that η1? η2 is the spectral measure of a p-stable random variable W on , 0 <p < 2, if and only if η1 and η2 are the spectral measures of p-stable random variables U and V on X and Y, respectively. Actually upper and lower bounds for in terms of the random variables U and V are obtained. When X = C(S), Y = C(T) with S, T compact metric spaces, and η1, and η2 are discrete, our results imply that if θi, θij are i.i.d. standard symmetric real valued p-stable random variables, 0 < p <2, xi?C(S), and yi?C(T), then the series ∑ijθijxi(s) yj(t) converges uniformly a.s. iff the series ∑iθixi(s) and ∑iθiyi(t) both converge uniformly a.s. When p = 2 this follows from Chevet's theorem on Gaussian processes. Several examples are given. One of them requires an interesting upper bound on the probability distribution of the maximum of i.i.d. p-stable random variables taking values in a general Banach space. 相似文献
19.
R.A. Maller 《Stochastic Processes and their Applications》1978,8(2):171-179
Let Xi be iidrv's and Sn=X1+X2+…+Xn. When EX21<+∞, by the law of the iterated logarithm for some constants αn. Thus the r.v. is a.s.finite when δ>0. We prove a rate of convergence theorem related to the classical results of Baum and Katz, and apply it to show, without the prior assumption EX21<+∞ that EYh<+∞ if and only if for 0<h<1 and δ> , whereas whenever h>0 and . 相似文献
20.
S. Ihara 《Journal of multivariate analysis》1974,4(1):74-87
The message m = {m(t)} is a Gaussian process that is to be transmitted through the white Gaussian channel with feedback: . Under the average power constraint, , we construct causally the optimal coding, in the sense that the mutual information It(m, Y) between the message m and the channel output Y (up to t) is maximized. The optimal coding is presented by , where and A(s) is a positive function such that . 相似文献