圆环上涉及重值及亏量的亚纯函数的唯一性

为了进一步丰富圆环上亚纯函数的唯一性理论,寻找更好的唯一性条件,本文研究了圆环上重值及亏量对亚纯函数唯一性的影响,得到两个圆环上亚纯函数与其导数涉及重值及亏量的唯一性定理,所得结果丰富了圆环上亚纯函数的唯一性理论.     

两指标随机微分方程的弱解和分布唯一性

本文定义了两指标随机微分方程(?)解的轨道唯一性和分布唯一性,进而研究了轨道唯一性和分布唯一性之间的关系,得出了两指标 Watanabe-Yamada 定理,并且得到了随机边界条件下方程(1)强解存在的充要条件。     

关于常微分方程解的存在唯一性簡介(再續)

§5.解的唯一性唯一性的研究集中在探求保証解唯一存在的各种具体条件和一般性的原則上。其次是研究唯一性定理的不同証法;也有少部分的工作討論破坏唯一性的充分条件;此外,还出現了初始条件給在无穷远处的唯一性問題。定理1 (Kamke普遍唯一性定理)。設ω(l,r)是定义在0     

一般型代数体函数的唯一性定理

研究了一般型代数体函数的唯一性问题,得到几个一般型代数体函数的唯一性定理,所得结论推广了已有的结果,丰富了代数体函数的唯一性理论.     

一类多时滞微分方程初值问题解的存在唯一性

研究了一类多时滞微分方程初值问题解的存在唯一性,用Picard方法证明了这类初值问题解的存在唯一性结论,它是常微分方程基本理论中著名的Picard存在唯一性定理的推广.     

多个亚纯函数的分担值与唯一性

本文研究了多个亚纯函数的分担值与唯一性问题,得到了一般情况下相应的唯一性定理。     

一类重特征方程柯西问题的存在唯一性

讨论了一类高维重特征方程栖西问题存在唯一性中的离散现象，证明发池方程的参数取某些值时存在唯一性有离散现象发生。并建立了存在唯一性与黎曼问题的联系。     

几类区域上不等维的边界唯一性定理

本文研究边界唯一性问题.利用构造函数与最大模原理的方法,得到了一些不等维的边界唯一性结果,将Burns-Krantz等人的等维边界唯一性结果推广到了不等维情形.     

等熵可压Navier-Stokes-Poisson方程局部强解适定性

该文得到了三维情形等熵可压Navier-Stokes-Poisson方程局部强解的存在性、唯一性及稳定性. 重要的是,该文允许初始密度真空的存在. 首先用推广形式的Gronwall不等式得到了强解的局部存在性,然后得到了较弱条件下的唯一性,在证明唯一性的同时得到了稳定性.     

一类函数方程C^2解的唯一性

讨论了一类迭代方程的唯一性,对「１」中关于唯一性的猜测给出了肯定的解答。     

Eigenvector p-Bases of Rings of Constants of Derivations

Let A be a UFD of characteristic p > 0, let 𝒵 be a set of some eigenvectors of a derivation of A. We prove, under some additional assumptions, a necessary and sufficient condition for 𝒵 to be a p-basis of the minimal ring of constants containing 𝒵. The main preparatory result is the unique decomposition theorem with respect to a factor from a given subalgebra containing A^p.     

Estimation of the number of components of finite mixtures of multivariate distributions

An estimator of the number of components of a finite mixture ofk-dimensional distributions is given on the basis of a one-dimensional independent random sample obtained by a transformation of ak-dimensional independent random sample. A consistency of the estimator is shown. Some simulation results are given in a case of finite mixtures of two-dimensional normal distributions.     

有资格限制的指派问题的求解方法

在实际的指派工作中，常会遇到某个人有没有资格去承担某项工作的问题，因此，本建立了有资格限制的指派问题的数学模型。在此数学模型中，将效益矩阵转化为判定矩阵，由此给出了判定此种指派问题是否有解的方法；在有解的情况下，进一步将效益矩阵转化为求解矩阵，从而将有资格限制的指派问题化为传统的指派问题来求解。最后给出了一个数值例子来说明这样的处理方法是有效的。     

Asymptotic Behavior of Solutions of Equations of Main Resonance

We investigate a system of two first-order differential equations that appears when averaging nonlinear systems over fast one-frequency oscillations. The main result is the asymptotic behavior of a two-parameter family of solutions with an infinitely growing amplitude. In addition, we find the asymptotic behavior of another two-parameter family of solutions with a bounded amplitude. In particular, these results provide the key to understanding autoresonance as the phenomenon of a considerable growth of forced nonlinear oscillations initiated by a small external pumping.     

Existence of normal Hall subgroups by means of orders of products

Let G be a finite group, let π be a set of primes and let p be a prime. We characterize the existence of a normal Hall π‐subgroup in G in terms of the order of products of certain elements of G. This theorem generalizes a characterization of A. Moretó and the second author by using the orders of products of elements for those groups having a normal Sylow p‐subgroup 6 . As a consequence, we also give a π‐decomposability criterion for a finite group also by means of the orders of products.     

Geometry of the Space of Phylogenetic Trees

We consider a continuous space which models the set of all phylogenetic trees having a fixed set of leaves. This space has a natural metric of nonpositive curvature, giving a way of measuring distance between phylogenetic trees and providing some procedures for averaging or combining several trees whose leaves are identical. This geometry also shows which trees appear within a fixed distance of a given tree and enables construction of convex hulls of a set of trees. This geometric model of tree space provides a setting in which questions that have been posed by biologists and statisticians over the last decade can be approached in a systematic fashion. For example, it provides a justification for disregarding portions of a collection of trees that agree, thus simplifying the space in which comparisons are to be made.     

Admissibility of estimators of the probability of unobserved outcomes

The problem of estimating the probability of unobserved outcomes or, as it is sometimes called, the conditional probability of a new species, is studied. Good's estimator, which is essentially the same as Robbins' estimator, namely the number of singleton species observed divided by the sample size, is studied from a decision theory point of view. The results obtained are as follows: (1) When the total number of different species is assumed bounded by some known number, Good's and Robbins' estimators are inadmissible for squared error loss. (2) If the number of different species can be infinite, Good's and Robbins' estimators are admissible for squared error loss. (3) Whereas Robbins' estimator is a UMVUE for theunconditional probability of a new species obtained in one extra sample point, Robbins' estimator is not a uniformly minimum mean squared error unbiased estimator of the conditional probability of a new species. This answers a question raised by Robbins. (4) It is shown that for Robbins' model and squared error loss, there are admissible Bayes estimators which do not depend only on a minimal sufficient statistic. A discussion of interpretations and significance of the results is offered. Research supported by NSF Grant DMS-88-22622.     

Products of operators of multidimensional structured model of systems

The author has previously defined the concept of a general system in terms of operators and operands. An operand is a mapping defined on a subset of an m-fold Cartesian product instead of the usual set and collection of k-ary relations on it. An operator is a kind of mapping between two collections of operands. Here subsystems, extensions, and the notion of P-semiexactness is studied. In particular we derive conditions such that P-semiexactness of a composition of operators, and of one factor, implies P-semiexactness of the other factor.     

Some properties of c-covers of a pair of Lie algebras

In [H. Safa and H. Arabyani, On c-nilpotent multiplier and c-covers of a pair of Lie algebras, Commun. Algebra 45(10) (2017), 4429–4434], we characterized the structure of the c-nilpotent multiplier of a pair of Lie algebras in terms of its c-covering pairs and discussed some results on the existence of c-covers of a pair of Lie algebras. In the present paper, it is shown under some conditions that a relative c-central extension of a pair of Lie algebras is a homomorphic image of a c-covering pair. Moreover, we prove that a c-cover of a pair of finite dimensional Lie algebras, under some assumptions, has a unique domain up to isomorphism and also that every perfect pair of Lie algebras admits at least one c-cover. Finally, we discuss a result concerning the isoclinism of c-covering pairs.     

On Location and Approximation of Clusters of Zeros of Analytic Functions

At the beginning of the 1980s, M. Shub and S. Smale developed a quantitative analysis of Newton's method for multivariate analytic maps. In particular, their α-theory gives an effective criterion that ensures safe convergence to a simple isolated zero. This criterion requires only information concerning the map at the initial point of the iteration. Generalizing this theory to multiple zeros and clusters of zeros is still a challenging problem. In this paper we focus on one complex variable function. We study general criteria for detecting clusters and analyze the convergence of Schroder's iteration to a cluster. In the case of a multiple root, it is well known that this convergence is quadratic. In the case of a cluster with positive diameter, the convergence is still quadratic provided the iteration is stopped sufficiently early. We propose a criterion for stopping this iteration at a distance from the cluster which is of the order of its diameter.