关于Teichmüller空间中一个问题的注记(英文)

本文指出了Ara Basmajian在美国数学会出版的“Contemporary Mathematics”第221 卷中提出的一个关于Teichmuller空间的问题的答案是完全否定的.     

极值拟共形扩张的一个问题

对每个单位圆到自身的拟对称映射h以及每个整数m≥ 4,引入了一个以K₀ (h) =sup{M (h(Q) ) /M(Q) ｜Q是以Δ为域的拓扑四边形 }为特殊情形的常数K^(m)₀ (h) ,建立了K^(m)₀ (h) =K₁(h)的一个充分必要条件并证明了存在无穷多个单位圆到自身的拟对称映射h具有性质K^(m)₀ (h)＜K₁(h)，其中K₁(h)为h的最大伸缩商。     

拟对称映射的最大伸缩商与边界伸缩商

文献[1]在研究单位圆周$\pd$上的拟对称自同胚的最大伸缩商与极值最大伸缩商之间的关系时,证明了:如果拟对称自同胚h的最大伸缩商K_q(h)不能在某个以开单位圆△为域、顶点在单位圆周$\pd$上的拓扑四边形Q处达到,则一定有K_q(h)≤H(h)成立,其中H(h)为h的边界伸缩商.这一结论在文献[1]中起着重要作用,但证明比较烦琐.该文主要给出该结论一个简单的证明,并且利用这一结论研究拟对称自同胚的最大伸缩商何时可以在某个拓扑四边形上达到.     

关于Teichmuller空间中一个问题的注记

本文指出了Ara Basmajian在美国数学会出版的“Contemporary Mathematics”第221卷中提出的一个关于Teichmuller空间的问题的答案是完全否定的。     

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。     

The eventually distance minimizing rays in moduli spaces

The eventually distance minimizing ray(EDM ray) in moduli spaces of the Riemann surfaces of analytic finite type with 3 g + n-3 0 is studied, which was introduced by Farb and Masur [5]. The asymptotic distance of EDM rays in a moduli space and the distance of end points of EDM rays in the boundary of the moduli space in the augmented moduli space are discussed in this article. A relation between the asymptotic distance of EDM rays and the distance of their end points is established. It is proved also that the distance of end points of two EDM rays is equal to that of end points of two Strebel rays in the Teichmu¨ller space of a covering Riemann surface which are leftings of some representatives of the EDM rays. Meanwhile, simpler proofs for some known results are given.     

THE REAL HYPER-ELLIPTIC SUBSPACES OF TEICHMüLLER SPACE AND MODULI SPACE

Although the existence and uniqueness of Strebel differentials are proved by Jenkins and Strebel, the specific constructions of Strebel differentials are difficult. Two special kinds of special Strebel differentials are constructed in [5, 6]. The Strebel rays [3] and the eventually distance minimizing rays [9] are important in Teichm¨uller spaces and moduli spaces, respectively. Motivated by the study of [3, 9], two special kinds of Strebel rays in the real hyper-elliptic subspace of Teichm¨uller space and two special kinds of EDM rays in the real hyper-elliptic subspace of moduli space are studied in this article.     

Pre-Schwarz导数意义下区域之间的距离

Lehto曾用Schwarz导数定义了边界多于一点的两个单连通区域的Mbius等价类之间的"距离",并猜测它是一个距离.但最近Bozin和Markovic否定了这一猜想.一个自然的问题就是:在Pre-Schwarz导数意义相应情况如何?用Pre-Schwarz导数给出了边界多于一点的两个单连通区域的仿射等价类之间的"距离",并证明了这样定义的"距离"是一个伪距离,即使将其限制在由具有解析边界的单连通区域的仿射等价类空间上也是如此.     

非Strebel点与可变性集合

研究万有Teichmuller空间Т中非Strebel点组成的子集.设z₀∈△为一定点.证明了对任意一个非Strebel点h,均存在一条以h为始点的全纯曲线γ:[0,1]→Т满足下列条件: (i)曲线γ位于以基点为心的球面上,即d_T(id,γ(t))=d_T(id,h)(t∈[0,1]); (ii)当t∈(0,1]时,点γ(t)的可变性集合V_γ(t)^[z₀]均有非空内部,即V_γ(t)^[z₀]≠φ.     

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] ≠ .