A Schwarz-Pick inequality for harmonic quasiconformal mappings and its applications

The main result of this paper is the sharp generalized Schwarz-Pick inequality for euclidean harmonic quasiconformal mappings with convex ranges, which generalizes a result given by Mateljevi?. As its applications, we obtain the property of quasi-isometry with respect to the Poincaré distance and an analogue of the Koebe theorem for this class of mappings.     

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.     

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.     

A note on harmonic quasiconformal mappings

In this note we show that a harmonic quasiconformal mapping f=u+iv with respect to the Poincaré metric of the upper half plane onto itself such that v(x,y)=v(y) or u(x,y)=u(x) is a conformal mapping.     

A note on Hamilton sequences of extremal Beltrami differentials

Let X be a hyperbolic Riemann surface and let μ be an extremal Beltrami differential on X with ${6\mu 6}_{\infty }\in (0,1)$. It is proved that, if $\{{?}_n\}$ is a Hamilton sequence of μ, then $\{{?}_n\}$ must be a Hamilton sequence of any extremal Beltrami differential ν contained in $[\mu ]$. This result proved a conjecture of the first author of this paper in 1996. This result is also a generalization of two known results.     

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.     

Truncations of extremal quasiconformal mappings and their applications

In this paper we give a necessary and sufficient condition to decide whether the Teichmüller equivalency class [α] of a truncation α induced by a uniquely extremal Beltrami differential is a Strebel point in T. We also obtain a necessary and sufficient condition of the unique extremality of α. Using the properties of truncations we provide a method to construct Hamilton sequences. We also get a sufficient condition for the extremality of f(z,t) to be equivalent to that of F(w,t). The corresponding results in the infinitesimal case are obtained, too.     

Extremal polygonal quasiconformal mappings and biLipschitz mappings

We show that the extremal polygonal quasiconformal mappings are biLipschitz with respect to the hyperbolic metric in the unit disk.     

Metric Density and Quasimobius Mappings

We study the notion of -density of metric spaces which was introduced by V. Aseev and D. Trotsenko. Interrelation between -density and homogeneous density is established. We also characterize -dense spaces as arcwise connected metric spaces in which arcs are the quasimobius images of the middle-third Cantor set. Finally, we characterize quasiconformal self-mappings of ⁿ in terms of -density.     

Riemann曲面之间的极值拟共形映射

设Ｓ和Ｒ是两个以单位圆为万有覆盖的Ｒｉｅｍａｎｎ曲面,ｆ：Ｓ→Ｒ为拟共形同胚,类似于ＫＳｔｒｅｂｅｌ的方法。我们引ｉｅｍａｎｎ嗣面Ｓ上的点ｐ０关于模边同伦类「ｆ０」的可变性集合Ｖ「ｆ０」「ｐ０」的概念并且证明可变性集合是Ｒ的一个紧的连通子集。     

拟共形映射的偏差定理

本文得到了一个空间拟共形映射的偏差定理,这一结果是F.W.Gehring的平面偏差定理的空间拓广。     

Non-Strebel points and variability sets

This paper studies the subset of the non-Strebel points in the universal Teichmuller space T. Let Z0 ∈ △be a fixed point. Then we prove that for every non-Strebel point h, there is a holomorphic curve γ : [0, 1]→ T with h as its initial point satisfying the following conditions.(1) The curve γ is on a sphere centered at the base-point of T, i.e. dT(id, γ(t)) = dT(id, h), (t ∈ [0, 1]).(2) For every t ∈ (0,1], the variability set Vγ(t)[Z0] of γ(t) has non-empty interior, i.e. Vγ(t) [Z0] ≠ .     

Some remarks on the geodesics in infinite dimensional Teichmüller spaces

LetB denote the set of those pointsp in an infinite dimensional Teichmüller space such that a geodesic between the zero point andp is not unique. Some properties of the setB are given.     

模和拟共形映射

研究了模和拟共形映射，得到了一个同胚为拟共形映射的几个条件．