On Strebel points

Any Beltrami coefficient μ on a hyperbolic Riemann surface X of infinite type represents a point [μ]T in the Teichmüller space T (X) and a point [μ]B in the tangent space of T (X) at the base point as well. The paper deals with the problem of determining whether that [μ]T is a Strebel point is equivalent to that [μ]B is an infinitesimal Strebel point.

A Sufficient Condition for Rigidity in Extremality of Teichmller Equivalence Classes by Schwarzian Derivative

The Strebel point is a TeichmOller equivalence class in the Teichmuller space that has a certain rigidity in the extremality of the maximal dilatation. In this paper, we give a sufficient condition in terms of the Schwarzian derivative for a Teichmuller equivalence class of the universal Teichmuller space under which the class is a Strebel point. As an application, we construct a Teichmuller equivalence class that is a Strebel point and that is not an asymptotically conformal class.

关于拟共型扩张的一点注记

证明了单位圆周上保向拟对称同胚h的极值拟共形扩张的伸缩商、边界邻域扩张的极值伸缩商以及以单位圆为内部的拓扑四边形在h作用下像与原像的共形模之比的极大值三者相等的一个充要条件。

依赖参数的无穷小Strebel点

给定单位圆Δ内一个有界可测函数μ(z),且∥μ∥∞=k∈(0,1/3),本文考察μ_(t)(z)=tμ(z)的Teichmüller等价类[μ_(t)].我们找到了一族全纯依赖于复参数t的有界可测函数ν_(t)∈[μ_(t)],使得ν_(t)(z)的无穷小Teichmüller等价类[ν_(t)]B均是无穷小Strebel点,且使得t↦[ν_(t)]B是单位圆Δ到无穷小Teichmüller空间Z的全纯映射.

Some Properties of an Operator on L~∞(△)and Its Applications

In this paper, we introduce an operator Hμ（z） on L^∞（△） and obtain some of its properties. Some applications of this operator to the extremal problem of quasiconformal mappings are given. In particular, a sufficient condition for a point r in the universal Teichmfiller space T（△） to be a Strebel point is obtained.

On a Relation between the Universal Teichmu¨ller Space and the Grunsky Operator

Being a Strebel point gives a sufficient condition for that the extremal Beltrami coefficient is uniquely determined in a Teichmiiller equivalence class. We consider how Strebel points are characterized. In this paper, we will give a new characterization of Strebel points in a certain subset of the universal Teichmfiller space by a property of the Grunsky operator.

On the equivalence of extremal Teichmller mapping

Let T(△) and B(△) be the Teichmuller space and the infinitesimal Teichmuller space of the unit disk △ respectively. In this paper, we show that [ν]B(△) being an infinitesimal Strebel point does not imply that [ν]T(△) is a Strebel point, vice versa. As an application of our results, problems proposed by Yao are solved.