关于Poincaré-Hopf的奇点指数公式

在一般的文献中,Poincaré-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Poincaré-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:     

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.     

高阶Euler数的推广及其应用

给出了高阶Euler数的一种Apostol型(看T.M.Apostol,[Pacific J.Math.,1(1951),161～167])推广,我们称之为高阶Apostol-Euler数,然后推导出它的几个递推公式并给出了它们的一些特殊情况和应用,从而得到了相应的高阶Euler数和经典Euler数的新公式.     

曲面的Galois三重覆盖

本文建立了曲面Galois三重覆盖的基本理论,证明了它的奇点可以通过典范的方法进行解消,并且得到了其不变量计算的基本公式。     

P~3中3次曲面与平面4次曲线间的关系

本文通过二重覆盖建立了P3中仅有二重的孤立奇点的3次曲面与平面带孤立奇点的4次曲线的对应关系，这种关系使我们能用平面4次曲线的奇点分类及几何性质研究P3中3次曲面的奇点类型及几何性质     

残数基本定理的推广与应用

本文引入单值解析函数在非弧立奇点的残数概念,并且把残数基本定理推广到函数在区域内可以有非孤立奇点的情形。最后,作为推广的残数基本定理的应用,我们导出了一些级数求和公式。     

THOM类与广义POINCARE-HOPF定理

本文得到球丛上的一个相交类公式及其与广义Poincare-Hopf定理的联系。作为应用,给出经典的Hopf定理与拓扑Gauss-Bonnet定理的一个统一证明。     

Hopf指数和公式的推广

<正> 设M是一个定向无边界的闭微分流形,ξ是M上一个光滑(切)向量场,它只有有限个孤立奇点.Hopf在ξ的每个奇点a处定义了一个指数Ind(ξ,a),并且证明了一条著名的指数和公式     

A Discrete Analog of Euler's Summation Formula

In this paper, we prove a discrete analog of Euler's summation formula. The difference from the classical Euler formula is in that the derivatives are replaced by finite differences and the integrals by finite sums. Instead of Bernoulli numbers and Bernoulli polynomials, special numbers P_n and special polynomials P_n(x) introduced by Korobov in 1996 appear in the formula.     

关于一般Hilbert二重级数定理的改进

应用Ｅｌｕｅｒ求和公式．证明对任意正整数ｎ及实数ｐ＞１．有这里，由此改进了一般Ｈｉｌｂｅｒｔ二重级数定理．     

Hyperharmonic series involving Hurwitz zeta function

We show that the sum of the series formed by the so-called hyperharmonic numbers can be expressed in terms of the Riemann zeta function. These results enable us to reformulate Euler's formula involving the Hurwitz zeta function. In additon, we improve Conway and Guy's formula for hyperharmonic numbers.     

De Moivre''s formula for quaternions

Euler's formula and De Moivre's formula for complex numbers are generalized for quaternions. De Moivre's formula implies that there are uncountably many unit quaternions satisfying xⁿ = 1 for n ≥ 3.     

Quasilinear Stochastic Hyperbolic Differential Equations with Nondecreasing Coefficient

In this note we prove a result of existence and uniqueness of solutions for a certain class of hyperbolic stochastic differential equations with additive white noise and nondecreasing coefficient. We then show the convergence of Euler's approximation scheme for this equation.     

s型加性算子与a型加性算子

设有定义于某线性空间而取值于规定了乘法的另一线性空间的映象A,满足 A(x+y)=B_1(y)A_x+B_2(x)AY+C(x,y), 则A称为泛义加性算子。本文所研究的s型加性算子与α型加性算子是泛义加性算子的特例。它们分别是通常加性算子与E.Hill等关于指数函数(算子)概念的拓广。但引入方式与结论不同。     

Convergence of votex methods in a bounded domain using linear finite elements

In this work, the vortex method for the initial boundary valueproblem of Euler's equation is considered. We analyze linearfinite element methods to solve the Poisson equation, whichrequire less operations to compute the velocity field from thevorticity. We prove that the rate of convergence of the linearfinite element scheme is independent of the vortex blob parameters.     

A new characterization of euler's gamma function by a functional equation

This paper gives a new characterization of Euler's gamma function from the aspect of complex analysis. To this end the Gauss multiplication formula is used.     

Cobordism invariance of the index of Callias-type operators

We introduce a notion of cobordism of Callias-type operators overcomplete Riemannian manifolds and prove that the index is preserved by such a cobordism. As an application, we prove a gluing formula for Callias-type index. In particular, a usual index of an elliptic operator on a compact manifold can be computed as a sum of indexes of Callias-type operators on two noncompact but topologically simpler manifolds. As another application, we give a new proof of the relative index theorem for Callias-type operators, which also leads to a new proof of the Callias index theorem.     

Multiple extensions of a finite Euler's pentagonal number theorem and the Lucas formulas

Motivated by the resemblance of a multivariate series identity and a finite analogue of Euler's pentagonal number theorem, we study multiple extensions of the latter formula. In a different direction we derive a common extension of this multivariate series identity and two formulas of Lucas. Finally we give a combinatorial proof of Lucas’ formulas.