关于Poincare—Hopf的奇点指数公式

在一般的文献中，Poincare-Hopf的曲面奇点指数公式的证明需要利用Euler的曲面示性数公式。本文将通过微分方程的定性方法，直接证明了Poincare-Hopf的奇点指数公式，然后作为简单的应用可得到Euler的曲面示性数公式。     

环面上具有一个奇点的积分曲线分布之拓扑结构

<正> 考虑带有一个奇点的微分方程在环面上所确定的积分曲线的拓扑结构.因环面之示性数为0,由环面上奇点的指数与环面示性数之间的关系知:所考虑的奇点的指数为0.因此,问题首先化为考虑在指数为0的奇点的邻近积分曲线分布的拓扑结构问题.引理1:至少有两条半积分曲线流入或流出奇点.这引理保证了可将奇点附近划分成扇形来考虑.     

不可定向曲面嵌入四维流形的法 Euler 数

设 M 是不可定向的连通闭曲面,具有 Euler 示性数 x.M 光滑嵌入四维球 S~4,法丛为 v.v 的 Euler 类 e(v)是上同调群 H~2(M,(?))中的元,其中(?)是由 w_1(v)=w_1(M)所决定的局部整系数.有名的 Whitney 猜想是说 e(v)[M]只可能取如下值之一:     

一类变系数混合时滞神经网络周期解的存在性和指数稳定性

在不需要激活函数有界的条件下,利用分析技巧和Poincaré映射给出了一类变系数混合时滞神经网络周期解的存在、唯一和指数稳定的充分条件.结论对神经网络的设计具有重要的意义.     

半代数集的一个计数定理及其应用

给出半代数集基数的计数原理和不可约紧代数流形上Euler示性数及亏格的算法.     

图上曲率维数不等式的若干等价性质

本文研究局部有限图上的曲率维数不等式CD(n,K)的若干等价性质,包括梯度估计、Poincaré不等式和逆Poincaré不等式.还得到了局部有限图上的修正曲率维数不等式CDE′(∞,K)的其中一个等价性质,即梯度估计.     

具有共振特征值的轨道翻转双同宿环分支

该文研究了具有轨道翻转的双同宿环四维系统,在主特征值共振和沿轨道奇点处切方向共振下的两种分支.我们分别在系统奇点小邻域内利用规范型的解构造一个奇异映射,再在双同宿环的管状邻域内引起局部活动坐标架,利用系统线性变分方程的解定义了一个正则映射,通过复合两个映射而得到分支研究中一类重要的Poincaré映射,经过简单的计算最终得到后继函数的精确表达式.对分支方程细致地研究,我们给出了原双同宿环的保存性条件,并证明了"大"1-同宿环分支曲面,2-重"大"1-周期轨分支曲面,"大"2-同宿环分支曲面的存在性、存在区域和近似表达式,及其分支出的"大"周期轨和"大"同宿轨的存在性区域和数量.     

Lévy噪声驱动的非对称耗散随机系统的Poincaré-型不等式和分部积分公式（英文）

研究了Lévy噪声驱动的非对称耗散随机系统的mild解的存在唯一性以及不变测度的存在性,随后得到了关于不变测度的Poincaré-型不等式和分部积分公式.     

Poincaré非正则积分问题的新进展

关于非Fuchs型方程,Poincaré曾经作出过重要的论断:没有方法可以求出非正则积分的显示表述.为了阐明这一论断的实质,我们证明对应定理:非正则积分是类具有树结构的新型解析函数,其中一部份解是通常的递推级数,而另一部则是不遵循递推关系的“树级数”.与经典理论(Hill-Poincaré-von Koch)计算无穷行列式的数值解不同,本法自然地给出严格解析解的显示表式.本法可以建立统一的解析理论以讨论一般变系数方程,包括有奇线在内的多种奇点.由于树级数具有自守性.我们讨论Poincaré猜测的意义.     

复合算子的双权Poincaré-型不等式

函数形式的Poincaré不等式在偏微分方程、位势分析等领域有着广泛的应用.给出LaplaceBeltrami算子和Green算子复合作用下A-调和张量的双权Poincaré不等式.它是经典Poincaré不等式的自然推广,并为A-调和张量性质的研究提供了有效工具.     

Distribution of types of symmetry of tensors of high degree

The asymptotic distribution of tensors of degree N in symmetry types is studied in this paper.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 155, pp. 181–186, 1986.     

Estimates of stability of characterization of additive types of distributions

An estimate of stability of characterization of distribution types is obtained for the case of additive types. Under some conditions, the estimate has the order ε^1/3L(ε), where L(ε) is a slowly varying function. Proceedings of the Seminar on Stability Problems for Stochastic Models, Moscow, Russia, 1996, Part I.     

Study of the blow-up of solutions of systems of equations of hydrodynamic type

Mathematical Notes - We study the initial boundary-value problem for three-dimensional systems of equations of pseudoparabolic type. The system is similar to the Oskolkov system, but differs from...     

一类完全正则半群簇子簇格的性质

本文研究了完全正则半群簇的子簇格［Ｖ＋∩ＰＶ，Ｖ＋∩ＰＶ］的某些格运算性质，我们证明了簇Ｖ＋∩ＰＶ可分解为Ｖ与Ｖ＋∩ＰＶ的并；对任意完全正则半群簇Ｗ，有Ｗ∩（Ｖ∨Ｖ＋∩ＰＶ）＝（Ｗ∩Ｖ）∨（Ｗ∩Ｖ＋∩ＰＶ）．特别地，我们得到了等式Ｖ＋∩ＰＶ＝Ｖ成立的若干条件．     

Characterization of types of asymptotic discernibility of families of hypotheses

We give a characterization of the types of asymptotic discernibility of families of hypotheses in the case of hypothetical measures that are not, in general, mutually absolutely continuous. The case when the logarithm of the likelihood ratio admits an asymptotic expansion of the type of an expansion with local asymptotic normality is examined in detail. Examples are studied.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 64–71, 1987.     

Bases of the identities of products of certain varieties of groups

The following theorem is proved: The product of any variety of two-step solvable groups and a variety having a finite basis of identity relations has a finite basis of identity relations.Translated from Matematicheskie Zametki, Vol. 5, No. 1, pp. 137–144, January, 1969.     

Birational aspects of the geometry of Varieties of Sums of Powers

Varieties of Sums of Powers describe the additive decompositions of a homogeneous polynomial into powers of linear forms. The study of these varieties dates back to Sylvester and Hilbert, but only few of them, for special degrees and number of variables, are concretely identified. In this paper we aim to understand a general birational behavior of VSP. To do this we birationally embed these varieties into Grassmannians and prove the rational connectedness of many VSP in arbitrary degrees and number of variables.