Zygmund函数在闭区间上最大值的估计

对任意实数集 R上的 Zygmund函数 f(x) ,满足条件 :|f(x+t) - 2 f(x) +f(x- t) | ‖ f‖z|t|,x,t∈ R ,且 f(0 ) =f (1 ) =0 ,本文证明maxx∈ [0 ,1 ] |f(x) | 13‖ f‖z.     

单位圆到凸区域上的调和拟共形映照

设F（x）=p（x）e^ir（x）为单位圆周到约当凸曲线Γ上的保向同胚映照.本文证明:若ess inf|F’（x）|>0且对于一切的φ∈R有|F（φ+x）+F（φ-x）-2F（φ）|≤M|x|^α,这里α>1,M为正常数,则ω=P[F]（z）为单位圆到凸区域Ω=int（Γ）上为调和拟共形映照.     

Fourier coefficients of Zygmund functions and analytic functions with quasiconformal deformation extensions

An open problem is to characterize the Fourier coefficients of Zygmund functions.This problem was also explicitly suggested by Nag and later by Teo and Takhtajan-Teo in the course of study of the universal Teichmu¨ller space.By a complex analysis approach,we give a characterization for the Fourier coefficients of a Zygmund function by a quadratic form.Some related topics are also discussed,including those analytic functions with quasiconformal deformation extensions.     

Grunsky算子的本性模

利用一个推广的Grunsky不等式,借助于单叶函数的拟共形延拓的边界伸缩商,我们给出Grunsky算子的本性模的一些估计.作为推论,我们推出Grunsky算子的紧性准则.     

拟共形映射与John域

本证明了有界一致域必定是Hohn域和Jphn域的拟共不变性．     

具有可积伸张同胚的Liouville定理

研究了具有可积伸张的同胚，在一定条件下得到了这类同胚的Liouville定理．     

紧致黎曼面上具有可积伸张及指定界值的拟共形同胚的极值映照

设S是亏格大于1的紧致黎曼面，本文对S上的拟共形ID—同胚定义了一种极值，证明了在每一个S到另外一紧致字文面S’的保向同胚同伦类中，如果存在一个广义的Teichmuller映照，那么在这种新定义的极值意义下，它是唯一最小的极值映照．     

有限偏差函数与调和函数

分别借助解析函数与调和函数两类函数的Dirichlet积分,利用相关文献给定边界值的拟共形映射极值伸缩商的估计方法,通过有限偏差函数和拟共形映射的关系估计了具有给定边界值的有限偏差函数的极值伸缩商.得到了解析函数的Dirichlet积分在有限偏差函数下具有拟不变性,同时给出有限偏差函数极值伸缩商的下界估计.     

拟共形映照和线性局部连通集

本文证明了Ｒｎ中线性局部连通集定义中的两个性质分别在保持无穷远点不变的拟共形映照下是不变的，并且指出保持无穷远点不变的条件是必不可少的．反过来，设ｆ是Ｒｎ上的同胚，ｆ（　）＝　，若线性局部连通集定义中的任意一条性质在ｆ下不变，则ｆ必是拟共形映照．     

On locally quasiconformal mappings

A homeomorphism w=f(z) of a domain D is called a locally quasiconformal mapping, if for each subdomain D' of D with 'D, the restriction of f(z) on D' is a quasiconformal mapping. We give some conditions for a measurable function μ(z) on the unit disc to be the complex dilatation of a locally quasiconformal mapping f which can be homeomorphically extended to the closed unit disc.     

拟圆的最大-最小不等式性质

利用区域的最大-最小不等式性质的拟共形不变性和圆的最大-最小不等式性质,得到了拟圆的最大-最小不等式性质.     

拟共不变集和拟圆的特征

证明了ＮＥＤ集在拟共形映照下的像仍是ＮＥＤ集，建立了关于拟圆的一个充分必要条件。     

Conformal Metrics on the Unit Ball in Euclidean Space

We study densities on the unit ball in euclidean space whichsatisfy a Harnack type inequality and a volume growth conditionfor the measure associated with . For these densities a geometrictheory can be developed which captures many features of thetheory of quasiconformal mappings. For example, we prove generalizationsof the Gehring-Hayman theorem, the radial limit theorem andfind analogues of compression and expansion phenomena on theboundary. 1991 Mathematics Subject Classification: 30C65.     

Counterexamples Concerning Quasiconformal Extensions of Strongly Starlike Functions

M. Fait, J. Krzyz and J. Zygmunt proved that a strongly starlike function of order α on the unit disk can be extended to a k-quasiconformal mapping with k ≤ sin（απ/2） on the whole complex plane C which fixes the point at infinity. An open question is whether such a function can be extended to a k-quasiconformal mapping with k 〈α to the whole plane C. In this paper we will give a negative approach to the question.     

拟共形映射与调和函数

本文利用调和函数的Ｄｉｒｉｃｈｌｅｔ积分来估计具有给定边界值的拟共形映射的极值伸缩商,回答Ｄ．Ｐａｒｔｙｋａ关于拟对称函数谱值和特征值的一个问题。     

QUASILINEAR-ADDITIVE PROPERTIES AND APPLICATIONS

In this article, the authors study some basic properties of the so-called quasilinear- additive functions, and some applications to the special functions of quasiconformal analysis are specified.     

拟共形映射和弱Cigar域

设f是R~n到R~n上的同胚,本文证明了f是拟共形映射的充要条件是f将R~n中的任一弱Cigar域映成R~n中的弱Cigar域。     

与星象函数有关的拟共形近于凸调和映射

讨论了一类解析部分为星象函数的拟共形近于凸调和映射的基本性质,得到了此类映射的系数不等式、积分表达式、增长定理、面积定理与部分和的近于凸半径.     

Moduli of quadrilaterals and extremal quasiconformal extensions of quasisymmetric functions

We establish a relationship between Strebel boundary dilatation of a quasisymmetric function of the unit circle and indicated by the change in the module of the quadrilaterals with vertices on the circle. By using general theory of universal Teichmüller space, we show that there are many quasisymmetric functions of the circle have the property that the smallest dilatation for a quasiconformal extension of a quasisymmetric function of the unit circle is larger than indicated by the change in the module of quadrilaterals with vertices on the circle. Received: December 8, 1996     

Propagation of Smallness and the Uniqueness of Solutions to Some Elliptic Equations in the Plane

In this paper we prove theorems on propagation of smallness and the uniqueness of solutions to some elliptic equations in the plane. We start with analogues of these theorems for harmonic functions and use their quasiinvariance under quasiconformal mappings as well as the connection of considered equations with such mappings.