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1.
We solve independently the equations 1/θ(x)θ(y)=ψ(x)−ψ(y)+φ(xy)/θ(xy) and 1/θ(x)θ(y)=σ(x)−σ(y)/θ(xy)+τ(x)τ(y), τ(0)=0. In both cases we find θ2=aθ4+bθ2+c. We deduce estimates for the spectral radius of a matrix of type(1/θ(x r x s )) (the accent meaning that the coefficients of the main diagonal are zero) and we study the case where thex r are equidistant.
Dédié to à Monsieur le Professeur Otto Haupt à l'occasion de son cententiare avec les meilleurs voeux  相似文献   

2.
In this paper we show that there exist mod 2 obstructions to the smoothness of 3-Sasakian reductions of spheres. Specifically, ifS is a smooth 3-Sasakian manifold obtained by reduction of the 3-Sasakian sphereS 4n−1 by a torus, and if the second Betti numberb 2(S)≥2 then dimS=7, 11, 15, whereas, ifb 2 (S)≥5 then dimS=7. We also show that the above bounds are sharp, in that we construct explicit examples of 3-Sasakian manifolds in the cases not excluded by these bounds. During the preparation of this work the authors were partially supported by an NSF grant. This article was processed by the author using the LATEX style file from Springer-Verlag.  相似文献   

3.
Summary.   Let X={X i } i =−∞ be a stationary random process with a countable alphabet and distribution q. Let q (·|x k 0) denote the conditional distribution of X =(X 1,X 2,…,X n ,…) given the k-length past:
Write d(1,x 1)=0 if 1=x 1, and d(1,x 1)=1 otherwise. We say that the process X admits a joining with finite distance u if for any two past sequences k 0=( k +1,…,0) and x k 0=(x k +1,…,x 0), there is a joining of q (·| k 0) and q (·|x k 0), say dist(0 ,X 0 | k 0,x k 0), such that
The main result of this paper is the following inequality for processes that admit a joining with finite distance: Received: 6 May 1996 / In revised form: 29 September 1997  相似文献   

4.
We investigate relationship between Kolmogorov–s condition and Petrov–s condition in theorems on the strong law of large numbers for a sequence of independent random variables X 1, X 2, … with finite variances. The convergence (S n ES n )/n → 0 holds a.s. (here, S n = Σ k=1 n X k ), provided that Σ n=1 DX n /n 2 < ∞ (Kolmogorov’s condition) or DS n = O(n 2/ψ(n)) for some positive non-decreasing function ψ(n) such that Σ1/(nψ(n)) < ∞ (Petrov’s condition). Kolmogorov’s condition is shown to follow from Petrov’s condition. Besides, under some additional restrictions, Petrov’s condition, in turn, follows from Kolmogorov’s condition.  相似文献   

5.
Let X 1, X 2,... be independent identically distributed random variables with distribution function F, S 0 = 0, S n = X 1 + ⋯ + X n , and n = max1⩽kn S k . We obtain large-deviation theorems for S n and n under the condition 1 − F(x) = P{X 1x} = el(x), l(x) = x α L(x), α ∈ (0, 1), where L(x) is a slowly varying function as x → ∞. __________ Translated from Lietuvos Matematikos Rinkinys, Vol. 45, No. 4, pp. 447–456, October–December, 2005.  相似文献   

6.
LetX be a probability space and letf: X n → {0, 1} be a measurable map. Define the influence of thek-th variable onf, denoted byI f (k), as follows: Foru=(u 1,u 2,…,u n−1) ∈X n−1 consider the setl k (u)={(u 1,u 2,...,u k−1,t,u k ,…,u n−1):tX}. More generally, forS a subset of [n]={1,...,n} let the influence ofS onf, denoted byI f (S), be the probability that assigning values to the variables not inS at random, the value off is undetermined. Theorem 1:There is an absolute constant c 1 so that for every function f: X n → {0, 1},with Pr(f −1(1))=p≤1/2,there is a variable k so that Theorem 2:For every f: X n → {0, 1},with Prob(f=1)=1/2, and every ε>0,there is S ⊂ [n], |S|=c 2(ε)n/logn so that I f (S)≥1−ε. These extend previous results by Kahn, Kalai and Linial for Boolean functions, i.e., the caseX={0, 1}. Work supported in part by grants from the Binational Israel-US Science Foundation and the Israeli Academy of Science.  相似文献   

7.
We study hypersurfaces in the Lorentz-Minkowski space \mathbbLn+1{\mathbb{L}^{n+1}} whose position vector ψ satisfies the condition L k ψ = + b, where L k is the linearized operator of the (k + 1)th mean curvature of the hypersurface for a fixed k = 0, . . . , n − 1, A ? \mathbbR(n+1)×(n+1){A\in\mathbb{R}^{(n+1)\times(n+1)}} is a constant matrix and b ? \mathbbLn+1{b\in\mathbb{L}^{n+1}} is a constant vector. For every k, we prove that the only hypersurfaces satisfying that condition are hypersurfaces with zero (k + 1)th mean curvature, open pieces of totally umbilical hypersurfaces \mathbbSn1(r){\mathbb{S}^n_1(r)} or \mathbbHn(-r){\mathbb{H}^n(-r)}, and open pieces of generalized cylinders \mathbbSm1(r)×\mathbbRn-m{\mathbb{S}^m_1(r)\times\mathbb{R}^{n-m}}, \mathbbHm(-r)×\mathbbRn-m{\mathbb{H}^m(-r)\times\mathbb{R}^{n-m}}, with k + 1 ≤ m ≤ n − 1, or \mathbbLm×\mathbbSn-m(r){\mathbb{L}^m\times\mathbb{S}^{n-m}(r)}, with k + 1 ≤ nm ≤ n − 1. This completely extends to the Lorentz-Minkowski space a previous classification for hypersurfaces in \mathbbRn+1{\mathbb{R}^{n+1}} given by Alías and Gürbüz (Geom. Dedicata 121:113–127, 2006).  相似文献   

8.
Let k≥2 be an integer and G = (V(G), E(G)) be a k-edge-connected graph. For XV(G), e(X) denotes the number of edges between X and V(G) − X. Let {si, ti}⊆XiV(G) (i=1,2) and X1X2=∅. We here prove that if k is even and e(Xi)≤2k−1 (i=1,2), then there exist paths P1 and P2 such that Pi joins si and ti, V(Pi)⊆Xi (i=1,2) and GE(P1P2) is (k−2)-edge-connected (for odd k, if e(X1)≤2k−2 and e(X2)≤2k−1, then the same result holds [10]), and we give a generalization of this result and some other results about paths not containing given edges.  相似文献   

9.
Let S⊂ℝ k+m be a compact semi-algebraic set defined by P 1≥0,…,P ≥0, where P i ∈ℝ[X 1,…,X k ,Y 1,…,Y m ], and deg (P i )≤2, 1≤i. Let π denote the standard projection from ℝ k+m onto ℝ m . We prove that for any q>0, the sum of the first q Betti numbers of π(S) is bounded by (k+m) O(q ). We also present an algorithm for computing the first q Betti numbers of π(S), whose complexity is . For fixed q and , both the bounds are polynomial in k+m. The author was supported in part by an NSF Career Award 0133597 and a Sloan Foundation Fellowship.  相似文献   

10.
It is shown that the realizability of the sequences ϕ=(a 1,…, a ), ψ=(b 1,…,b n ) and ϕ+ψ is a sufficient condition for the realizability of ϕ+ψ by a graph with a ϕ-factor ifb i ≦1 fori=1,…,n. The condition is not sufficient in general. A necessary and sufficient condition for the realizability of ϕ+ψ by a graph with a ϕ-factor is given for the case that ϕ is realizable by a star and isolated vertices.  相似文献   

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