Riemann–Poisson manifolds and Kähler–Riemann foliations

Riemann–Poisson manifolds were introduced by the author in C. R. Acad. Sci. Paris, Ser. I 333 (2001) 763–768, and studied in detail in preprint math.DG/0206102. Kähler–Riemann foliations form an interesting subset of the Riemannian foliations with remarkable properties (see Ann. Global Anal. Geom. 21 (2002) 377–399). In this Note we will show that to give a regular Riemann–Poisson structure on a manifold P is equivalent to give a Kähler–Riemann foliation on P such that the leafwise symplectic form is invariant with respect to all local foliation-preserving perpendicular vector fields. Finally, we give some examples of such manifolds. To cite this article: M. Boucetta, C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

Riemann—Lebesgue theorem

Пусть?(x) — ограниченн ая функция на отрезке [0,1] и ее функция распределен ияΦ(t) удовлетворяет услов ию $$\Phi \left( t \right) + \Phi \left( { - t} \right) = 1.$$ Еслиf(x) — конечная поч ти всюду функция, то дл яF _n (t) — функции распределе ния произведенияf(x)?(nx) — вы полнены соотношения и В частности, еслиf(x) — и нтегрируемая функци я, то из (1) следует, что $$\mathop {\lim }\limits_{n \to \infty } \mathop \smallint \limits_0^1 f\left( x \right)\varphi \left( {nx} \right)dx = 0 $$      

完备Riemann流形之共轭点

本文证明了具非负曲率完备Ｒｉｅｍａｎｎ测地线为无共轭点测地线的充要条件；并由此证明了若该流形上的截面含有一无共轭点测地线的切向量，则其对应的截曲率为零．     

Gromov Hyperbolicity of Riemann Surfaces

We study the hyperbolicity in the Gromov sense of Riemann surfaces. We deduce the hyperbolicity of a surface from the hyperbolicity of its ＂building block components＂. We also prove the equivalence between the hyperbolicity of a Riemann surface and the hyperbolicity of some graph associated with it. These results clarify how the decomposition of a Riemann surface into Y-pieces and funnels affects the hyperbolicity of the surface. The results simplify the topology of the surface and allow us to obtain global results from local information.     

双准周期的Riemann边值问题

对于双周期的Riemann边值问题 Φ (t)=G(t)Φ~-(t) g(t),t∈L,(0.1)其中L是基本胞腔S_0中某一光滑曲线L_0及其所有周期合同曲线的并,不论L_0是封闭或开口的情况,都已有较完善的研究。本文将讨论双准周期的类似问题。这种问题在实际应用中也是很有用的,因为在许多周期现象中,某些量是准周期的;例如周期应力的平面弹性问题,其位移一般就是准     

带根号的Riemann边值问题

本文讨论了一类开口弧带根号的Riemann边值问题,利用构造辅助函数ω(z)的方法解决了未知函数在开口弧情形下的单值性问题,获得了该问题的封闭解.     

双准周期的 Riemann 边值问题

对于双周期的 Riemann 边值问题Φ (t):G(t)Φ-(t) g(t),t∈L,(0.1)其中 L 是基本胞腔 S。中某一光滑曲线 L。及其所有周期合同曲线的并,不论L。是封闭或开口的情况,都已有较完善的研究.本文将讨论双准周期的类似问题。这种问题在实际应用中也是很有用的,因为在许多周期现象中,某些量是准周期的;例如周期应力的平面弹性问题,其位移一般就是准周期的.在讨论这个问题之前,我们对双准周期解析函数的一些性质作些说明.     

Hankel算子与Riemann猜测

本文证明了著名的Ｒｉｅｍａｎｎ猜测等价于单位圆的Ｈａｒｄｙ空间上的某族Ｈａｎｋｅｌ算子的奇异值的单重性．     

单准周期的Riemann边值问题

本文研究了光滑封闭曲线情况下的加法与乘法单准周期Riemann边值问题,运用保角变换的方法,获得了单准周期函数的一些性质,并且对解在无穷远处作适当要求下给出了单准周期边值问题的解法.     

Riemann问题的间断有限元

用时空全离散间断零次有限元对Riemarm问题进行了数值求解，没有出现振荡，很好的模拟了稀疏波的逐渐稀疏化和激波的剧烈变化。     

Riemann的Zeta函数论简介

本文将介绍Riemann Zeta函数的发展梗概、基本结果和它的主要研究方面。众所周知,Riemann Zeta函数的定义是     

一类Riemann边值逆问题

本文给出了一类Ｒｉｅｍａｎｎ边值逆问题的正则型与非正则型情况的数学提法和解法     

二阶复椭圆Riemann—Hilbert边值问题

讨论了一般二阶非线性椭圆复方程的Riemann-Hilbert边值问题,首先给出Riemann-Hilbert问题及其适应性的概念,其次给出改进后的边值问题解的表述并证明了它的可解性,最后导出原Rremann-Hilbert边值问题的可解条件。     

Riemann Sums and Möbius

Let S be the set of square-free natural numbers. A Hilbert-Schmidt operator, A, associated to the Möbius function has the property that it maps from \({ \cup _{0 < r < \infty }}{l^r}(s)\) to \({ \cap _{0 < r < \infty }}{l^r}(s)\), injectively. If 0 < r< 2 and ξ ∈ l^r (S), the series \({f_\zeta } = \sum\nolimits_{n \in s} {A\zeta (x)cos2\pi nx} \) converges uniformly to an element of f_ξR₀, i.e., a periodic, even, continuous function with equally spaced Riemann sums, \(\sum\nolimits_{j = 0}^{N - 1} {{f_\zeta }} (j/N) = 0,N = 1,2....\) If \({A_{\zeta \lambda }} = \lambda {\zeta _\lambda },{\zeta _\lambda }(1) = 1\), then ξ_λ is multiplicative. If \({f_{{\zeta _\lambda }}} \in {\Lambda _a}\), the space of α-Lipschitz continous functions, for some α > 0, and if χ is any Dirichlet character, then L(s, χ) ≠ 0, Res > 1 ? α. Conjecturally, the Generalized Riemann Hypothesis (GRH) is equivalent to f_ξ ∈ Λ_α, α < 1/2, ξ ∈ l^r (S), 0 < r < 2. Using a 1991 estimate by R. C. Baker and G. Harman, one finds GRH implies f_ξ ∈ Λ_α, α < 1/4, ξ ∈ l^r (S), 0 < r < 2. The question of whether R₀ ∩ Λ_α ≠ {0} for some positive α > 0 is open.     

The Riemann Hypothesis, the Generalized Riemann Hypothesis, and the Cesáro Operator

A result due to Nyman establishes the equivalence of the Riemann hypothesis with the density of a set of functions in L ²[0, 1]. Here a large class of analytic functions is considered, which includes the Riemann zeta function and the Dirichlet L-functions as well as functions not given by a Dirichlet series. For each such function there is an associated integral operator T on L ²[0, 1] such that has no zeros in Re(s) > 1/2 iff the operator T has dense range iff a specified set of functions is dense in L ²[0, 1].      

风机叶片的Riemann几何研究

用 Riemann几何方法研究了风机叶片的设计问题 .得到了螺旋线切曲面的 Riemann曲率张量 Rlkij=0 ,从而指出了切曲面为可展曲面 ,并给出了设计单片式连续曲面结构叶片的有关参数 .     

Fredholm Composition Operators on Riemann Surfaces

It is proved that the invertibility of a composition operator on the differential form space for a Riemann surface is equivalent to its Fredholmness. In addition, the Fredholmness of weighted composition operators is discussed.     

A Microlocal Riemann–Hilbert Correspondence

We present a microlocal version of the Riemann–Hilbert correspondence for regular holonomic D-modules. We show that a regular holonomic system of microdifferential equations is associated to a perverse sheaf concentrated in degree 0. Moreover, we show that this perverse sheaf can be recovered from the local system it determines on the complementary of its singular locus. We characterize the classes of perverse sheaves and local systems associated to regular holonomic systems of microdifferential equations.