关于随机最远点

首先给出在随机赋范模中子集的随机最远点的概念．进一步,利用随机一致凸性和经典一致凸性之间的联系证明了下面的结果：令（E,｜｜·｜｜）为完备的随机一致凸的随机赋范模,S为E中几乎处处有界并在（ε, λ）一拓扑下的闭子集,则具有S中随机最远点的集合稠于E．     

有关不连续随机增算子的随机不动点

本文利用Zorn引理和锥理论,研究了不连续随机算子的随机不动点的存在性问题,得到了几个有关不连续随机增算子的随机不动点定理.     

Rainbows in the Hypercube

Let Q_n be a hypercube of dimension n, that is, a graph whose vertices are binary n-tuples and two vertices are adjacent iff the corresponding n-tuples differ in exactly one position. An edge coloring of a graph H is called rainbow if no two edges of H have the same color. Let f(G,H) be the largest number of colors such that there exists an edge coloring of G with f(G,H) colors such that no subgraph isomorphic to H is rainbow. In this paper we start the investigation of this anti-Ramsey problem by providing bounds on f(Q_n,Q_k) which are asymptotically tight for k = 2 and by giving some exact results.     

Cut Points and Diffusions in Random Environment

In this article we investigate the asymptotic behavior of a new class of multidimensional diffusions in random environment. We introduce cut times in the spirit of the work done by Bolthausen et al. (Ann. Inst. Henri Poincaré 39(5):527–555, 2003) in the discrete setting providing a decoupling effect in the process. This allows us to take advantage of an ergodic structure to derive a strong law of large numbers with possibly vanishing limiting velocity and a central limit theorem under the quenched measure.     

Random Points in the Unit Ball of ℓ n p

We show that two limit results from random matrix theory, due to Marčenko–Pastur and Bai–Yin, are also valid for matrices with independent rows (as opposed to independent entries in the classical theory), when rows are uniformly distributed on the unit ball of ℓⁿ_p, under proper normalization. Research was supported in part by the European Network PHD, FP6 Marie Curie Actions, MCRN-511953 and was done in part while the author was visiting the University of Athens.     

On the Behavior of Random Walk Around Heavy Points

Consider a symmetric aperiodic random walk in Z ^d , d≥3. There are points (called heavy points) where the number of visits by the random walk is close to its maximum. We investigate the local times around these heavy points and show that they converge to a deterministic limit as the number of steps tends to infinity.     

Subcodes of the Projective Generalized Reed-Muller Codes Spanned by Minimum-Weight Vectors

We use methods of Mortimer [19] to examine the subcodes spanned by minimum-weight vectors of the projective generalized Reed-Muller codes and their duals. These methods provide a proof, alternative to a dimension argument, that neither the projective generalized Reed-Muller code of order r and of length over the finite field F _q of prime-power order q, nor its dual, is spanned by its minimum-weight vectors for 0<r<m–1 unless q is prime. The methods of proof are the projective analogue of those developed in [17], and show that the codes spanned by the minimum-weight vectors are spanned over F _q by monomial functions in the m variables. We examine the same question for the subfield subcodes and their duals, and make a conjecture for the generators of the dual of the binary subfield subcode when the order r of the code is 1.     

Inequalities for Convex Hulls of Random Points

 We prove an estimate for the probability that the convex hull of j independent random points is disjoint from the convex hull of k further independent random points chosen in a plane convex body. (Received 25 January 2000)     

Inequalities for Convex Hulls of Random Points

 We prove an estimate for the probability that the convex hull of j independent random points is disjoint from the convex hull of k further independent random points chosen in a plane convex body.     

Existence Theorems of Random Nash Equilibrium Points for Random Set-valued Maps

ＥｘｉｓｔｅｎｃｅＴｈｅｏｒｅｍｓｏｆＲａｎｄｏｍＮａｓｈＥｑｕｉｌｉｂｒｉｕｍＰｏｉｎｔｓｆｏｒＲａｎｄｏｍＳｅｔ┐ｖａｌｕｅｄＭａｐｓＬｕｏＱｕｎ（罗群）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＧｕｉｚｈｏｕＮｏｒｍａｌＵｎｉｖｅｒｓｉ...     

随机弱内向映射的多个随机不动点定理

利用随机不动点指数理论及Banach常微分方程理论的随机结果,证明了关于随机弱内向映射一个随机三解定理.     

Spanned patterns for the logical analysis of data

In a finite dataset consisting of positive and negative observations represented as real valued n-vectors, a positive (negative) pattern is an interval in Rⁿ with the property that it contains sufficiently many positive (negative) observations, and sufficiently few negative (positive) ones. A pattern is spanned if it does not include properly any other interval containing the same set of observations. Although large collections of spanned patterns can provide highly accurate classification models within the framework of the Logical Analysis of Data, no efficient method for their generation is currently known. We propose in this paper, an incrementally polynomial time algorithm for the generation of all spanned patterns in a dataset, which runs in linear time in the output; the algorithm resembles closely the Blake and Quine consensus method for finding the prime implicants of Boolean functions. The efficiency of the proposed algorithm is tested on various publicly available datasets. In the last part of the paper, we present the results of a series of computational experiments which show the high degree of robustness of spanned patterns.     

Percentage Points of the Largest Among Student's T Random Variable

Let us consider k( 2) independent random variables U₁, . . . ,U_k where U_i is distributed as the Student's t random variable with a degree of freedom m_i, i=1, . . . ,k. Here, m₁, . . . ,m_k are arbitrary positive integers. We denote m=(m₁, . . . ,m_k) and U_k:k=max {U₁, . . . ,U_k}, the largest Student's t random variable. Having fixed 0< <1, let a a(k,) and h_m h_m (k,) be two positive numbers for which we can claim that (i) ^k(a)–^k(–a)=1–, and (ii) P{–h_m U_k:k h_m}=1–. Then, we proceed to derive a Cornish–Fisher expansion (Theorem 3.1) of the percentage point h_m. This expansion involves a as well as expressions such as _i=1 ^k m_i ^–1, _i=1 ^km_i ^–2, and _i=1 ^k m_i ^–3. The corresponding approximation of h_m is shown to be remarkably accurate even when k or m₁, . . . ,m_k are not very large.     

Conjugate Points on a Geodesic with Random Curvature

We study conjugate points on a renewable geodesic on which the curvature is a random process. We construct the upper bound for the mean distance between neighboring conjugate points.     

Large Deviations View Points for Heavy-Tailed Random Walks

Let X ₁, X ₂,... be a sequence of i.i.d. non-negative random variables with heavy tails. W e study logarithmic asymptotics for the distributions of the partial sums S _n = X ₁ + ··· + X _n . Our main interest is in the crude estimates P(S _n > n ^x ) n ^{–x + 1} for appropriate values of x where is a specific parameter. The related conjecture proposed by Gantert (Stat. Probab. Lett. 49, 113–118) is investigated.     

椭圆上距离任意已知点最远或最近的点分析

采用微分几何与函数极值分析相结合的方法 ,利用椭圆星形线的特性 ,确定了椭圆上的几何切点与距离函数极值点的对应关系 ,指出了距离函数极值点存在的几何区域 (或条件 ) ,建立了最远点及最近点的准确数值计算方法 .