R1^m+1中拟迷向类空超曲面

设f:M^m→R1^m+1是无脐点类空超曲面,则在Mm上可以定义四个基本的共形不变量:共形度量g,共形1-形式C,共形第二基本形式B,共形Blaschke张量A.如果存在光滑函数λ和常数μ,使得A+μB=Ag,则称M^m是拟迷向类空超曲面.本文不仅构造了拟迷向类空超曲面的例子,同时在相差R1^m+1的一个共形变换下,本文还完全分类了拟迷向类空超曲面.     

Lorentz空间R_1~(n+1)中类空λ-超曲面的刚性定理（英文）

本文研究了Lorentz空间R_1~(n+1)中完备的类空λ-超曲面的刚性问题.利用推广了的L-算子的性质和一些积分不等式,最终得到了关于这类超曲面的若干刚性定理,其中包括R_1~(n+1)中加权的完备类空自收缩子的刚性,推广了此前欧氏空间完备λ-超曲面的相关结果.     

赋范空间的λ——性质

本文讨论赋范空间的λ－性质，得到了ｌ１（ｘｎ）和Ｌ∞（Ｘｎ）具有λ－性质的充分必要条件，解决了Ｒ．Ｍ．Ａｒｏｎ和Ｒ．Ｈ．Ｌｏｈｍａｎ在文（１）中提出的两个问题，此外，还研究了Ｂａｎａｃｈ空间，ｌｐ（Ｘｎ）（１〈ｐ〈∞）具有一致λ－性质的充分必要条件。     

n维Anti-de Sitter空间中类空超曲面的类时Gauss像的奇点

本文利用奇点理论研究了n维Anti-deSitter空间中的类空超曲面,介绍了类空超曲面的局部微分几何,定义了类时Anti-deSitterGauss像及Anti-deSitter高度函数,并进一步的利用Anti-deSitter高度函数族和流形间的切触理论研究了类时Anti-deSitterGauss像的几何意义及类空超曲面的通有性.最后研究了类空超曲面的AdS-Monge型.     

De Sitter空间中半对称的类空超曲面

给出了De Sitter空间S1^n 1(1)（n≥3)的类空超英面是半对称的充要条件，决定了S1^n 1(1)（n≥3)的半对称类空超曲面的局部结构，证明了S1^n 1(1)（n≥3)具有常平均曲率的连通完备的半对称类空超曲面或是全脐的，或是具有两上不同主曲率的等参超曲面。     

某些椭圆曲线的L－级数的L（1）的非零性

本文考虑了椭圆曲线Γ＿Ｄ：Ｘ￣３＋Ｙ￣３＝ＤＺ￣３．以ＬＤ（ｓ）记Γ＿Ｄ的ＨｅｃｋｅＬ－级数．由Ｌ＿Ｄ（ｓ）的解析延拓我们将Ｌ＿Ｄ（１）展成有限项之和，然后通过建立ｙ￣２＝ｘ￣３－１６的一个处处有好的约化的模型，证明了当ｐ≡２或５（ｍｏｄ　９）时，Ｌ＿（ｐ￣２）（１）≠０．这些结果是对Ｂｉｒｃｈ和Ｓｗｉｎｎｅｒｆｏｎ－Ｄｙｅｒ猜想的支持。     

有界F-支撑函数和类空Wulff形

给定H_+~n上适合凸条件的正函数F,对L~(n+1)中具有非退化Gauss映射的类空超曲面引入了Θ_F曲率.对适当的F,本文证得:具有常Θ_F曲率,且F-支撑函数介于两个负常数之间的类空超曲面必是类空Wulff形.在F=1的情况下,对H_i/H_n为常数的类空超曲面也建立了类似的唯一性结果.     

某些椭圆曲线的L—级数的L（1）的非零性

本文考虑了椭圆曲线ΓＤ：Ｘ＾３＋Ｙ＾３＝ＤＺ＾３。以ＬＤ（ｓ）记ΓＤ的ＨｅｃｋｅＬ－级数。由ＬＤ（ｓ）的解析延拓我们将ＬＤ（１）展成有限项之和，然后通过建立ｙ＾２＝ｘ＾３－１６的一个处处有好的约化的模型，证明了当ｐ≡２或５（ｍｏｄ９）时，Ｌｐ（１）≠０，Ｌｐ＾２（１）≠０。这些结果是对Ｂｉｒｃｈ和Ｓｗｉｎｎｅｒｆｏｎ－Ｄｙｅｒ猜想的支持。     

4维Lorentz空间形式中的类空Willmore曲面

本文研究4维Lorentz空间形式中的类空Willmore曲面.
这是Lorentz共形几何中与$S^4$中的Willmore曲面理论相对应的一个主题.
对每一个类空Willmore曲面定义了两类变换,
导出左/右polar曲面和伴随曲面.
这些新的曲面都是与原来曲面共形的Willlmore曲面,
并且它们满足一些有趣的对偶定理.
应用这些对偶定理, 我们分类了4维Lorentz空间形式中的类空Willmore球面. 最后作为例子, 构造了一族齐性类空Willmore环面.     

de Sitter 空间中的常平均曲率完备类空超曲面

设Ｍ是常曲率ｃ的ｄｅ Ｓｉｔｔｅｒ空间Ｓ１＾ｎ＋１（ｃ）的常平均曲率的完备类空超曲面,Ｓ表示第二形式的范数平方。本文证明：差Ｓ〈２√ｎ－１ｃ,则Ｍ是全脐的和等距于一球面。     

Constant Mean Curvature Surfaces Foliated by Circles in Lorentz–Minkowski Space

We prove that a spacelike surface in L3 with nonzero constant mean curvature and foliated by pieces of circles in spacelike planes is a surface of revolution. When the planes containing the circles are timelike or null, examples of nonrotational constant mean curvature surfaces constructed by circles are presented. Finally, we prove that a nonzero constant mean curvature spacelike surface foliated by pieces of circles in parallel planes is a surface of revolution.     

Lightlike surfaces of Darboux-like indicatrixes and binormal indicatrixes of spacelike curves in lightcone 3-space

In this paper, by introducing a new frame on spacelike curves lying in lightcone 3-space, we investigate the geometric properties of the lightlike surface of the Darboux-like indicatrix and the lightlike surface of the binormal indicatrix generated by spacelike curves in lightcone 3-space. As an extension of our previous work and an application of the singularity theory, the singularities of the lightlike surfaces of the Darboux-like indicatrix and the lightlike surface of the binormal indicatrix are classified, several new invariants of spacelike curves are discovered to be useful for characterizing these singularities, meanwhile, it is found that the new invariants also measure the order of contact between spacelike curves or principal normal indicatrixes of spacelike curves located in lightcone 3-space and two-dimensional lightcone whose vertices are at the singularities of lightlike surfaces. One concrete example is provided to illustrate our results.     

INTEGRABLE SYSTEM AND SPACELIKE SURFACES WITH PRESCRIBED MEAN CURVATURE IN MINKOWSKI 3-SPACE

1IntroductionItiswell-knownthattheclassicalWeierstrass-EnneperrepresentationformuladescribeschinalsurfacesinEuclidean3-spaceR3intermsoftheirGaussmapsandauxiliaryholomorphicfunctions[1].Moregenerally,aremarkablerepresentationforlllulahasbeendiscoveredbyKenmotsu[2]forarbitrarysurfaCesinR3withnonvallishingmeancurvature,whichdescribesthesesurfacesintermsoftheirGaussmapsandmeancurvaturefunctions.Recently,Konopelchenko[31rediscoveredthisrepresentationformulaindifferentbutequivalentformillconnect…     

On the Surface the Fermi–Walker Derivative in Minkowski 3-Space

In this paper Fermi–Walker derivative and Fermi–Walker parallelism and non-rotating frame concepts are given along the curve lying on the spacelike surface and the timelike surface in Minkowski 3-space. First, we consider a curve lying on the spacelike surface and investigate the Fermi–Walker derivative along the curve. The concepts which Fermi–Walker derivative and its theorems are analyzed along the curve lying on the spacelike surface in Minkowski 3-space. And then we consider a curve lying on the timelike surface and investigate the Fermi–Walker derivative along the curve.     

Closed Strong Spacelike Curves,Fenchel Theorem and Plateau Problem in the 3-Dimensional Minkowski Space

The authors generalize the Fenchel theorem for strong spacelike closed curves of index 1 in the 3-dimensional Minkowski space, showing that the total curvature must be less than or equal to 2π. Here the strong spacelike condition means that the tangent vector and the curvature vector span a spacelike 2-plane at each point of the curve γ under consideration. The assumption of index 1 is equivalent to saying that γ winds around some timelike axis with winding number 1. This reversed Fenchel-type inequality is proved by constructing a ruled spacelike surface with the given curve as boundary and applying the Gauss-Bonnet formula. As a by-product, this shows the existence of a maximal surface with γ as the boundary.     

An alternative moving frame for a tubular surface around a spacelike curve with a spacelike normal in Minkowski 3-space

We describe a robust method for constructing a tubular surface surrounding a spacelike curve with a spacelike principal normal in Minkowski 3-Space. Our method is designed to eliminate undesirable twists and wrinkles in the tubular surface’s skin at points where the curve experiences high torsion. In our construction the tubular surface’s twist is bounded by the spacelike curve’s curvature and is independent of the spacelike curve’s torsion.      

二维Minkowski空间R~(2.1)中混合型时空曲面的等温参数

对于三维Minkowski空间中的混合型时空曲面，证明了其在类空部分和类时部分上分别存在光滑的，并且连续到交界线上的等温参数．进一步，给出了混合型时空曲面存在在其类空部分和类时部分上是光滑的，而在交界线上是连续的等温多数的一个必要条件．     

三维De Sitter与Anti-de Sitter空间中的等参曲面

A spacelike surface M in 3-dimensional de sitter space S13 or 3-dimensional anti-de Sitter space H13 is called isoparametric, if M has constant principal curvatures. A timelike surface is called isoparametric, if its minimal polynomial of the shape operator is constant. In this paper, we determine the spacelike isoparametric surfaces and the timelike isoparametric surfaces in S13 and H13.     

Singularities of maximal surfaces

We show that the singularities of spacelike maximal surfaces in Lorentz–Minkowski 3-space generically consist of cuspidal edges, swallowtails and cuspidal cross caps. The same result holds for spacelike mean curvature one surfaces in de Sitter 3-space. To prove these, we shall give a simple criterion for a given singular point on a surface to be a cuspidal cross cap. Dedicated to Yusuke Sakane on the occasion of his 60th birthday.     

On the mean curvature of spacelike surfaces in certain three-dimensional Robertson–Walker spacetimes and Calabi–Bernstein’s type problems

Several uniqueness results for the spacelike slices in certain Robertson–Walker spacetimes are proved under boundedness assumptions either on the mean curvature function of the spacelike surface or on the restriction of the time coordinate on the surface when the mean curvature is a constant. In the nonparametric case, a uniqueness result and a nonexistence one are proved for bounded entire solutions of some constant mean curvature spacelike differential equations.