THE CLASSIFICATION OF CONVEX ORDERS ON AFFINE ROOT SYSTEMS

We classify all total orders with a convex property on the positive root system of an arbitrary untwisted affine Lie algebra g. Such total orders are called convex orders and are used to construct convex bases of Poincaré-Birkhoff-Witt type of the upper triangular subalgebra U_q ⁺ of the quantized universal enveloping algebra U_q (g).     

NOTE ON THE PROJECTIVE DIFFERENTIAL GEOMETRY OF SPACE CURVES

<正> INTRODUGTION.1.In the proiective theory of a curve in ordinary space thereare introduced various systems of tetrahedrons associated to a pointof the curve.Most of them are,more or less,artificial and consequently 1.he geometrical significance of the projective invariantsrequires notions more complicated than the double ratio of fourelements of a primitive geometric forin.Bompiani has overcomethis difficulty by projecting the curve from the point of Sannia andreducing the problem to the theory of projective invariants of contact     

仿射框架的新准则

仿射框架是小波理论中很基本的概念.熟知的关于仿射框架的Daubechies判别法引用了由绝对值|ψ(ajω)ψ(ajω+lT)|算出的量来作判别.在本文建立的新判别法中引用了由ψ(ajω)ψ(ajω+lT)的适当组合的代数和算出的量来作判别.当ψ为偶函数时,新的判别法优于Daubechies判别法.     

仿射框架的新准则

仿射框架是小波理论中很基本的概念.熟知的关于仿射框架的Daubechies判别法引用了由绝对值| (ajω) (ajω lT)|算出的量来作判别.在本文建立的新判别法中引用了由(ajω) (ajω lT)的适当组合的代数和算出的量来作判别.当为偶函数时,新的判别法优于Daubechies判别法.     

有理B-样条曲线、曲面的包络性质

研究有理Bezier曲线和B-样条曲线、曲面的包络性质,愈来愈广泛,因为它从包络磨光的角度解释了曲线、曲面的一种几何构造特征,形象地说明了模型是由多边形或多面体逐步磨光的结果.     

一类椭圆曲线的正整数点

本文研究了一类椭圆曲线的正整数点个数的问题.利用二元四次Diophantine方程的新近结果,给出了这类椭圆曲线的正整数点个数的上界,推广了文献[4]中的结果     

THE CLOSED CURVES ON POSITIVE-TYPE HYPERSURFACES AND THE PERIODS OF NONLINEAR OSCILLATIONS

本文在Ｒｎ＋１中定义了一类超曲面并讨论了其上闭测地线长度的下界以及Ｈａｍｉｌｔｏｎ系统的周期解的最小周期，这类超曲面比星形超曲面广泛，因而本文结论包含了文献〔１〕、〔２〕、〔３〕中的相应结论     

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.     

PROPER AFFINE DEFORMATIONS OF THE ONE-HOLED TORUS

A Margulis spacetime is a complete at Lorentzian 3-manifold M with free fundamental group. Associated to M is a noncompact complete hyperbolic surface ∑ homotopy-equivalent to M. The purpose of this paper is to classify Margulis spacetimes when ∑ is homeomorphic to a one-holed torus. We show that every such M decomposes into polyhedra bounded by crooked planes, corresponding to an ideal triangulation of ∑. This paper classifies and analyzes the structure of crooked ideal triangles, which play the same role for Margulis spacetimes as ideal triangles play for hyperbolic surfaces.     

联系复平面上由弧长所引出的 Radon 测度的加权不等式

本文考虑联系 R~n 中 Radon 测度的极大算子的加权不等式,然后应用所得的结果得到沿复平面上正则曲线的极大算子及奇异积分的加权模不等式.     

REGULAR FUNCTIONS ON A PRODUCT OF AFFINE VARIETIES

ABSTRACT

Assume that f:X×Y→Z is a map from the product of two affine varieties into another affine variety such that f is a regular map when one variable is fixed. We show that f is a regular map if the underlying field is not countably infinite. The condition is indispensable.     

由仿射线诱导的图的第二次成分

本文研究了有限域上n维仿射空间的仿射线诱导的图Γ的第二次成分Γ2(α)的代数和组合性质.利用在仿射群作用下的轨道的代表元,证明了第二次成分Γ2(α)是连通的、正则的,但不是边正则的.     

SOME THEOREMS ON CONVEX HYPERSURFACES IN AN AFFINE SPACE

Let M and M~* be hypersurfaces in an affine space A~(n+1) of dimension n+1. The main results of this paper are the following:(1) Two types of integral formulas for M and M~*.(2) Some conditions for an affine convex hypersurface to be an affine sphere.(3) Some conditions for M and M~* to be different only by an affine transformation or a translation.     

ON PSEUDO-HOLOMORPHIC CURVES IN COMPLEX GRASSMANNIANS

0.IntroductionAsiswellknown,beginingwithaharmonicmapf:M-Gm(C")fromaRiemannstirfacetoacomplexGrassmannian,onecanobtaintheharmonicsequencesbyusingthe0-transformand0--transform.[1]Whenfisholomorphic,eachelementintheharmonicscsquenceiscalledapseudo-holomorphiccurveandthecorespondingmapiscalledapseudosholomorphicmap.[2]Theimportanceofsuchmapscomesfromthefactthatanyharmonicmapgb:M-- CPu~GI(C" ')ispseudo-holomorphicifIdeg(rk)I>n(g--1)wheredeg(rk)isthedegreeofacandgisthegenusofM.13'4]In[5]J.Bol…     

B—样条逼近曲线的应用

引进了一种构造曲线的逼近技术，它放松了曲线应包含所有数据点这一严格要求。为了度量一曲线能逼近已给数据多边形的好坏，使用了移动控制点的概念。     

THE ASSOCIATED FAMILIES OF SEMI-HOMOGENEOUS COMPLETE HYPERBOLIC AFFINE SPHERES

Hildebrand classified all semi-homogeneous cones in R~3 and computed their corresponding complete hyperbolic affine spheres.We compute isothermal parametrizations for Hildebrand's new examples.After giving their affine metrics and affine cubic forms,we construct the whole associated family for each of Hildebrand's examples.The generic member of these affine spheres is given by Weierstrass P,ζ and σ functions.In general any regular convex cone in R~3 has a natural associated S~1-family of such cones,which deserves further studies.     

ON CLIFFORD'S THEOREM FOR VECTOR BUNDLES ON ALGEBRAIC CURVES

Let X be a smooth projective curve of genus g ≥ 2 and E a rank r spanned vector bundle on X with deg(E)/rank(E) ≤ g ? 1. Here we give lower bounds for deg(E) refining the classical theorem of Clifford. Most results are for vector bundles with rank ≤ 5.