On the Joint Path Length Distribution in Random Binary Trees

During the 10th Seminar on Analysis of Algorithms , MSRI, Berkeley, June 2004, Knuth posed the problem of analyzing the left and the right path length in a random binary tree. In particular, Knuth asked about properties of the generating function of the joint distribution of the left and the right path lengths. In this paper, we mostly focus on the asymptotic properties of the distribution of the difference between the left and the right path lengths. Among other things, we show that the Laplace transform of the appropriately normalized moment generating function of the path difference satisfies the first Painlevé transcendent . This is a nonlinear differential equation that has appeared in many modern applications, from nonlinear waves to random matrices. Surprisingly, we find out that the difference between path lengths is of the order n ^5/4 where n is the number of nodes in the binary tree. This was also recently observed by Marckert and Janson. We present precise asymptotics of the distribution's tails and moments. We will also discuss the joint distribution of the left and right path lengths. Throughout, we use methods of analytic algorithmics such as generating functions and complex asymptotics, as well as methods of applied mathematics such as the Wentzel, Kramers, Brillouin (WKB) method.     

Lower Bounds for the Nodal Length of Eigenfunctions of the Laplacian

We prove lower bounds for the length of the zero set of aneigenfunction of the Laplace operator on a Riemann surface; inparticular, in non-negative curvature, or when the associated eigenvalueis large, we give a lower bound which involves only the square root ofthe eigenvalue and the area of the manifold (modulo a numericalconstant, this lower bound is sharp).     

Topologies of Nodal Sets of Random Band-Limited Functions

It is shown that the topologies and nestings of the zero and nodal sets of random (Gaussian) band-limited functions have universal laws of distribution. Qualitative features of the supports of these distributions are determined. In particular, the results apply to random monochromatic waves and to random real algebraic hypersurfaces in projective space. © 2018 Wiley Periodicals, Inc.     

Nonlinear Dynamics of Marine Systems in Random Waves

The dynamics of ships or offshore structures is influenced by several different effects, some of which have a distinctly nonlinear characteristic. Even though in many situations the motion can sufficiently be described by linear models, nonlinear phenomena play a crucial role in the investigation of some more critical operating conditions: Large amplitude motions, sudden jumps in the dynamical behavior and sensitivity to the initial conditions are likely to occur under some circumstances. The response of floating systems such as moored buoys and barges in regular waves can be approximated by analytical or numerical techniques. These analyses reveal the characteristics of different periodic motions. In order to determine how these responses change under a more general forcing, the motion of floating structures under the influence of random disturbances is described by probability distributions. Different mathematical tools can efficiently be applied to models with few degrees of freedom. The localized statistical linearization used here is also promising for larger systems. Modelling aspects of offshore structures and random waves are discussed as well as the determination of probability distributions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A New Proof of Szemerédi's Theorem for Arithmetic Progressions of Length Four

((Without abstract)) Submitted: November 1997, Final version: May 1998     

离散型指数差分布

本文提出了一个离散型概率分布:指数差分布,推导了该分布的最可能成功次数、数学期望和方差,探讨了该分布与几何分布的关系,给出了该分布在马尔可夫链模型中的应用。     

Random Minimum Length Spanning Trees in Regular Graphs

r -regular n-vertex graph G with random independent edge lengths, each uniformly distributed on (0, 1). Let mst(G) be the expected length of a minimum spanning tree. We show that mst(G) can be estimated quite accurately under two distinct circumstances. Firstly, if r is large and G has a modest edge expansion property then , where . Secondly, if G has large girth then there exists an explicitly defined constant such that . We find in particular that . Received: Februray 9, 1998     

随机环境中多物种分枝游动质点密度矩阵的极限分布

本文研究了随机环境中的多物种分枝游动于时刻k,位置x的质点密度矩阵序列{M~(k)(x)}k>1的极限分布。我们在证明了M~(k)(x),k>1,x∈Z是k个独立同分布的矩阵值随机元的乘积的基础上,主要证明了随机序列{logM_(ij)~(k)(x)}k>1依某种意义规范后是渐近正态的。     

The Poisson Distribution for Linear Statistics of Random Permutations

We examine the asymptotic distribution laws of integer-valued linear statistics defined via the multiplicities of lengths of cycles comprising a random permutation taken with equal probability. We establish necessary and sufficient conditions for the weak convergence to the Poisson limit law. The approach can be applied to investigate other logarithmic structures. __________ Translated from Lietuvos Matematikos Rinkinys, Vol. 45, No. 4, pp. 537–552, October–December, 2005.     

随机模拟算法在体育教学评价中应用

针对传统体育教学评价中优劣判别的绝对性,以及多评价结论非一致性问题,构建一种凸显自身优势的自主优势评价方法,评价中运用一种基于概率型随机模拟算法,通过计算各评价对象之间的优胜度,来评判评价对象的优势.经过算例验证方法的有效性,得到带有概率信息的评价结论.     

三维粘弹性分层介质中平稳随机波的传播

研究平稳随机波在粘弹性分层横观各向同性介质中的传播问题．将岩层考虑为分层介质,各层性质不同,岩层位于基岩上面,并且认为基岩比岩层刚很多,在基岩处给出随机激励．在频率和波数域中将控制方程化为常微分方程求解．对常微分方程,应用两点边值问题的精细积分法进行求解．因此,近年来发展的应用于结构随机振动的虚拟激励法可推广于当前分层岩层响应的计算．     

随机增长网络的度分布

增长和择优机制是无标度网络中的两种重要的演化机制,在分析BA模型的基础上,提出了一种新的节点增长方式,即考虑了新增节点的连边数是随机变量的情况,从而建立了随机增长网络模型,并利用随机过程理论得到了在这种增长方式下网络的度分布,结果表明这个网络是无标度网络。     

Distribution of Arithmetic Functions on Particular Subsets of Integers

Lithuanian Mathematical Journal - Let Q1, . . . , Qt ∈?[x] be polynomials with no constant term for which each linear combination m1Q1(x) + · · ·+mtQt (x) with m1, . . ....     

负二项分布随机变量的分解定理

给出了负二项分布的分解定理,并进一步研究了负二项分布的有关性质和近似计算公式.在复杂排队系统中离散状态下顾客等待时间分布的概率计算中起到了重要作用.     

Limiting Spectral Distribution of Random k-Circulants

Consider random k-circulants A _k,n with n????,k=k(n) and whose input sequence {a _l } _l??0 is independent with mean zero and variance one and $\sup_{n}n^{-1}\sum_{l=1}^{n}\mathbb{E}|a_{l}|^{2+\delta}<\infty$ for some ??>0. Under suitable restrictions on the sequence {k(n)} _n??1, we show that the limiting spectral distribution (LSD) of the empirical distribution of suitably scaled eigenvalues exists, and we identify the limits. In particular, we prove the following: Suppose g??1 is fixed and p ₁ is the smallest prime divisor of g. Suppose $P_{g}=\prod_{j=1}^{g}E_{j}$ where {E _j }_1??j??g are i.i.d. exponential random variables with mean one. (i) If k ^g =?1+sn where s=1 if g=1 and $s=o(n^{p_{1}-1})$ if g>1, then the empirical spectral distribution of n ^?1/2 A _k,n converges weakly in probability to $U_{1}P_{g}^{1/(2g)}$ where U ₁ is uniformly distributed over the (2g)th roots of unity, independent of P _g . (ii) If g??2 and k ^g =1+sn with $s=o(n^{p_{1}-1})$ , then the empirical spectral distribution of n ^?1/2 A _k,n converges weakly in probability to $U_{2}P_{g}^{1/(2g)}$ where U ₂ is uniformly distributed over the unit circle in ?², independent of P _g . On the other hand, if k??2, k=n ^o(1) with gcd?(n,k)=1, and the input is i.i.d. standard normal variables, then $F_{n^{-1/2}A_{k,n}}$ converges weakly in probability to the uniform distribution over the circle with center at (0,0) and radius $r=\exp(\mathbb{E}[\log\sqrt{E}_{1}])$ .     

关于等差数列在三素数中的分布

基于著名的Hardy-Littlewood猜想,证明了长为3的素数等差数列出现频率最高的公差是素数连乘.另外,举例说明了这种素数等差数列并不一定是三素数最喜欢的分布形式.