G2,n中的可兼共形调和曲面

本文通过建立复Ｇｒａｓｓｍａｎｎ流形Ｇ２，ｎ中调和曲面的Ｇａｕｓｓ丛的基本公式，在适当的拓扑条件下给出了Ｇ２，ｎ中可兼共形调和曲面的构造定理．推广和改进了Ｂｕｒｓｔａｌｌ和Ｗｏｏｄ的低亏格曲面的结果．     

仿射极大曲面的Weierstrass公式及其应用

本文主订研究如何用Ｗｅｉｅｒｓｔｒａｓｓ公式构造仿射极大曲面；并应用Ｗｅｉｅｒｓｔｒａｓｓ公式证明Ａ＾３中不存在紧致无边的仿射极大曲面。     

关于Finsler曲面的几何和拓扑

本文在Ｆｉｎｓｌｅｒ曲面上定义了一个新的不变量Ｈ。该不变量等于零刻画了Ｒｉｅｍａｎｎ流形。文章给出了Ｈ的一个上界并且构造了Ｈ为常值的非Ｒｉｅｍａｎｎ的Ｆｉｎｓｌｅｒ曲面。此外，本文还推广了Ｌａｎｄｓｂｅｒｇ曲面的Ｇａｕｓ－Ｂｏｎｎｅｔ－Ｃｈｅｒｎ定理并分类了非正曲率的Ｆｉｎｓｌｅｒ曲面。     

三角域上Bernsterin—Bezier曲面的一种推广

本文给出了三角域上Ｂｅｒｎｓｔｅｉｎ－Ｂｅｚｉｅｒ曲面的一种推广，并研究了这种曲面的性质和算法。     

欧氏空间中具有共形Gauss映照的曲面

本文考虑欧氏空间中具有共形Ｇａｕｓｓ映照的曲面．从Ｇａｕｓｓ映照的观点给出了 ｖｅｒｏｎｅｓｅ曲面的一个新特征．     

拟欧氏空间IR_n~(n 2)中类空曲面的Gaus映照

本文讨论拟欧氏空间ＩＲｎ＋２ｎ中的类空曲面，利用Ｇａｕｓ映照给出这类曲面的一般表示公式，从而推广了Ａｋｕｔａｇａｗａ和Ｎｉｓｈｉｋａｗａ的结果．     

Bcklund变换与类时极值平移曲面

首先通过选取适当的等温参数将三维Ｍｉｎｋｏｗｓｋｉ空间Ｒ２．１中的全脐点类时曲面与Ｌｉｏｕｖｉｌｅ方程相联系．其次，通过类时曲面上的类光曲线坐标将Ｒ２．１中的类时极值曲面与齐次波动方程相联系．进一步，利用Ｌｉｏｕｖｉｌｅ方程与齐次波动方程之间的Ｂａｃｋｌｕｎｄ变换，我们可以从三维Ｍｉｎｋｏｗｓｋｉ空间中一个全脐点的类时曲面得到该空间中一个类时极值平移曲面．     

Backlund变换与类时极值平移曲面

首先通过选取适当的等温参数将三维Ｍｉｎｋｏｗｓｋｉ空间Ｒ＾２．１中的全脐点集时曲面与Ｌｉｏｕｖｉｌｌｅ方程相联系。其次，通过类时曲面上的类光曲线坐标将Ｒ＾２．１中的类时极值曲面与齐次波动方程相联系。进一步，利用Ｌｏｕｖｉｌｌｅ方程与齐次波动方程之间的Ｂａｃｋｌｕｎｄ变换，我们可以从三维Ｍｉｎｋｏｗｓｋｉ空间中一个全脐点的类时曲面得到该空间中一个类时极值平移曲面。     

黎曼曲面上Riemann边值问题的一点注记

本文给出了紧黎曼曲面上关于Ｒｉｅｍａｎｎ边值问题的Ａｂｅｌ定理，由此定理可得经典Ａｂｅｌ定理，并且解决了非紧黎曼曲面上关于Ｒｉｅｍａｎｎ边值问题的ＣｏｕｓｉｎＩ，ＩＩ问题。     

关于3维欧氏空间中一族嵌入极小曲面的一个注记

本文证明了在 Ｄ． Ｈｏｆｆｍａｎ和 Ｗ．Ｈ． Ｍｅｅｋｓ， Ⅲ［４］给出的 ３维欧氏空间的一族嵌入极小曲面中，每一个曲面与其自身的和曲面是平凡的极小核心．     

On One Family of Minimal Tori in ℝ<Superscript>3</Superscript> with Planar Embedded Ends

We construct new examples of complete minimal tori in the three-dimensional Euclidean space with an arbitrary even number n ≥ 6 of planar embedded ends.     

New Examples of Willmore Surfaces in S n

A surface x: M S ⁿ is called a Willmore surface if it is a criticalsurface of the Willmore functional _M (S – 2H ²)dv, where H isthe mean curvature and S is the square of the length of the secondfundamental form. It is well known that any minimal surface is aWillmore surface. The first nonminimal example of a flat Willmoresurface in higher codimension was obtained by Ejiri. This example whichcan be viewed as a tensor product immersion of S ¹(1) and a particularsmall circle in S ²(1), and therefore is contained in S ⁵(1) gives anegative answer to a question by Weiner. In this paper we generalize theabove mentioned example by investigating Willmore surfaces in S ⁿ (1)which can be obtained as a tensor product immersion of two curves. We inparticular show that in this case too, one of the curves has to beS ¹(1), whereas the other one is contained either in S ²(1) or in S ³(1). In the first case, we explicitly determine the immersion interms of elliptic functions, thus constructing infinetely many newnonminimal flat Willmore surfaces in S ⁵. Also in the latter casewe explicitly include examples.     

There exist no 2-type surfaces in E 3 which are images under stereographic projection of minimal surfaces in S 3

In this paper we deal with the following particular case of a weaker conjecture by B. Y. Chen: Are there 2-type Willmore surfaces in E ³? In particular we prove that the above question has a negative answer when the surface is the image under stereographic projection of a minimal surface in S ³.     

Willmore Surfaces in S n

A surface x> : M S ⁿ is called a Willmore surface if it is a critical surface of the Willmore functional. It is well known that any minimal surface is a Willmore surface and that many nonminimal Willmore surfaces exists. In this paper, we establish an integral inequality for compact Willmore surfaces in S ⁿ and obtain a new characterization of the Veronese surface in S ⁴ as a Willmore surface. Our result reduces to a well-known result in the case of minimal surfaces.     

A note on Kneser-Haken finiteness

Kneser-Haken finiteness asserts that for each compact 3-manifold there is an integer such that any collection of c(M)$"> closed, essential, 2-sided surfaces in must contain parallel elements. We show here that if is closed, then twice the number of tetrahedra in a (pseudo)-triangulation of suffices for .

     

Willmore two-spheres in the four-sphere

Genus zero Willmore surfaces immersed in the three-sphere correspond via the stereographic projection to minimal surfaces in Euclidean three-space with finite total curvature and embedded planar ends. The critical values of the Willmore functional are , where , with . When the ambient space is the four-sphere , the regular homotopy class of immersions of the two-sphere is determined by the self-intersection number ; here we shall prove that the possible critical values are , where . Moreover, if , the corresponding immersion, or its antipodal, is obtained, via the twistor Penrose fibration , from a rational curve in and, if , via stereographic projection, from a minimal surface in with finite total curvature and embedded planar ends. An immersion lies in both families when the rational curve is contained in some or (equivalently) when the minimal surface of is complex with respect to a suitable complex structure of .

     

Synchronism of an incompressible non-free Seifert surface for a knot and an algebraically split closed incompressible surface in the knot complement

We give a necessary and sufficient condition for knots to bound incompressible non-free Seifert surfaces.

     

极小曲面中的若干问题

本文综述了Ｅ＾ｎ和Ｓ＾ｎ中极小曲面的若干经典结果和最新发展，指出了一些尚未解决的问题，在第４节中，对Ｅ＾３中极小曲面的Ｆｕｊｉｍｏｔｏ定理给出了一个更直接的证明。     

On Some Special Surfaces Connected with Convex Surfaces of the Lobachevskii Space

With a closed convex surface in a Lobachevskii space we associate four special surfaces: the inscribed and circumscribed spheres, a sphere rolling freely over the inner side of , and an equidistant surface over whose inner side rolls freely. We find an exact dependence between these four special surfaces.