Maximal surfaces and the universal Teichmüller space

We show that any element of the universal Teichmüller space is realized by a unique minimal Lagrangian diffeomorphism from the hyperbolic plane to itself. The proof uses maximal surfaces in the 3-dimensional anti-de Sitter space. We show that, in AdS _n+1, any subset E of the boundary at infinity which is the boundary at infinity of a space-like hypersurface bounds a maximal space-like hypersurface. In AdS₃, if E is the graph of a quasi-symmetric homeomorphism, then this maximal surface is unique, and it has negative sectional curvature. As a by-product, we find a simple characterization of quasi-symmetric homeomorphisms of the circle in terms of 3-dimensional projective geometry.     

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 Teichmüller 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 Teichmüller space by a property of the Grunsky operator.     

Notes on Univalent Functions and the Universal Teichmüller Space

万有Ｔｅｉｃｈｍüｌｅｒ空间Ｔ是所有规范的拟对称同胚组成的集合．在Ｂｅｒｓ嵌入下，Ｔ与Δ上共形映射的Ｓｃｈｗａｒｚ导数密切相关．本文讨论由规范的对称同胚所组成的子集Ｔ０的相应性质．