Teichmüller theory of the universal hyperbolic lamination

A commentary on Teichmüller's paper "Extremale quasikonforme Abbildungen und quadratische Differentiale"

We provide a commentary on Teichm{ü}ller's paper "Extremale quasikonforme Abbildungen und quadratische Differentiale" (Extremal quasiconformal mappings of closed oriented Riemann surfaces), Abh. Preuss. Akad. Wiss., Math.-Naturw. Kl. 1940, No.22, 1-197 (1940). The paper is quoted in several works, although it was read by very few people. Some of the results it contains were rediscovered later on and published without any reference to Teichm{ü}ller.In this commentary, we highlight the main results and the main ideas contained in that paper and we describe some of the important developments they…

TeichmUller's work on the type problem (To appear in Vol. VII of the Handbook of Teichm{ü}ller theory, 2020)

The type problem is the problem of deciding, for a simply connected Riemann surface, whether it is conformally equivalent to the complex plane or to the unit dic in the complex plane. We report on Teichm{ü}ller's results on the type problem from his two papers Eine Anwendung quasikonformer Abbildungen auf das Typenproblem (An application of quasiconformal map-pings to the type problem) (1937) and Untersuchungen{ü}ber kon-forme und quasikonforme Abbildungen (Investigations on con-formal and quasiconformal mappings) (1938). They concern simply connected Riemann surfaces defined as branched cover…

Teichmüller空间上的水平度量

The horocyclic metric on Teichm{ü}ller spaces

本文从共形视角研究Teichmüller空间上的水平度量，将Thurston的理论扩展到任意亏格的Riemann面，并通过复Legendre变换建立Weil-Petersson symplectic形式的对偶关系。

A commentary on Teichmüller's paper "Verschiebungssatz der quasikonformen Abbildung" (A displacement theorem of quasiconformal mapping)

This is a commentary on Teichm{ü}ller's paper Ein Verschiebungssatz der quasikonformen Abbildung (A displacement theorem of quasiconformal mapping), published in 1944. We explain in detail how Teichm{ü}ller solves the problem of finding the quasiconformal mapping from the unit disc to itself, sending 0 to a strictly negative point on the real line, holding the boundary of the disc pointwise fixed and with the smallest quasiconformal dilatation. We mention also some consequences of this extremal problem and we ask a question.

A note on Nicolas-Auguste Tissot: At the origin of quasiconformal mappings (to appear in Vol. VII of the Handbook of Teichm{ü}ller Theory)

Nicolas-Auguste Tissot (1824--1897) was a French mathematician and cartographer. He introduced a tool which became known among geographers under the name ``Tissot indicatrix'', and which was widely used during the first half of the twentieth century in cartography. This is a graphical representation of a field of ellipses, indicating at each point of a geographical map the distorsion of this map, both in direction and in magnitude. Each ellipse represented at a given point is the image of an infinitesimal circle in the domain of the map (generally speaking, a sphere representing the surface of…

Earthquakes and Thurston's boundary for the Teichmüller space of the universal hyperbolic solenoid

A measured laminations on the universal hyperbolic solenoid $§$ is, by our definition, a leafwise measured lamination with appropriate continuity for the transverse variations. An earthquakes on theuniversal hyperbolic solenoid $§$ is uniquely determined by a measured lamination on $§$; it is a leafwise earthquake with the leafwise earthquake measure equal to the leafwise measured lamination. Leafwise earthquakes fit together to produce a new hyperbolic metric on $§$ which is transversely continuous and we show that any two hyperbolic metrics on $§$ are connected by an earthquake. We also esta…

A Fréchet topology on measured laminations and Earthquakes in the hyperbolic plane

We prove that the bijective correspondence between the space of bounded measured laminations $ML_b(\mathbb{H})$ and the universal Teichmüller space $T(\mathbb{H})$ given by $λ\mapsto E^λ|_{S^1}$ is a homeomorphism for the Fréchet topology on $ML_b(\mathbb{H})$ and the Teichmüller topology on $T(\mathbb{H})$, where $E^λ$ is an earthquake with earthquake measure $λ$. A corollary is that earthquakes with discrete earthquake measures are dense in $T(\mathbb{H})$. We also establish infinitesimal versions of the above results.

Non rigidity of hyperbolic laminations

In this note we prove infinite dimensionality of the Teichmüller space of a hyperbolic Riemann surface lamination of a compact space having a simply connected leaf.

Projective structures, grafting, and measured laminations

We show that grafting any fixed hyperbolic surface defines a homeomorphism from the space of measured laminations to Teichmuller space, complementing a result of Scannell-Wolf on grafting by a fixed lamination. This result is used to study the relationship between the complex-analytic and geometric coordinate systems for the space of complex projective ($\CP^1$) structures on a surface. We also study the rays in Teichmuller space associated to the grafting coordinates, obtaining estimates for extremal and hyperbolic length functions and their derivatives along these grafting rays.

Limits of Teichmüller geodesics in the Universal Teichmüller space

Thurston's boundary to the universal Teichmüller space $T(\mathbb{H})$ is the set of asymptotic rays to the embedding of $T(\mathbb{H})$ in the space of geodesic currents; the boundary is identified with the projective bounded measured laminations $PML_{bdd}(\mathbb{H})$ of $\mathbb{H}$. We prove that each Teichmüller geodesic ray in $T(\mathbb{H})$ has a unique limit point in Thurston's boundary to $T(\mathbb{H})$ unlike in the case of closed surfaces.

弯曲Teichmüller空间和特征流形

Bending Teichmüller spaces and character varieties

本文研究了通过沿固定测度流形L弯曲Fuchsian表示得到的映射b_L：从Fricke-Teichmüller空间T到表面的PSL_2(C)-特征流形χ的映射，并证明该映射是equivariant symplectic real-analytic嵌入，并且对于几乎所有的测度流形都是proper的。此外，还展示了该

万有 Teichmüller 空间中的发散测地线

Divergent geodesics in the Universal Teichmüller space

本文首次构造了在万有 Teichmüller 空间 Thurston 边界附近发散的广义 Teichmüller 射线，并借助 Kronecker 逼近定理构造出极限集同胚于任意有限维立方体的射线例子。

A Thurston boundary for infinite-dimensional Teichmüller spaces

For a compact surface $X_0$, Thurston introduced a compactification of its Teichmüller space $\mathcal T(X_0)$ by completing it with a boundary $\mathcal{PML}(X_0)$ consisting of projective measured geodesic laminations. We introduce a similar bordification for the Teichmüller space $\mathcal T(X_0)$ of a noncompact Riemann surface $X_0$, using the technical tool of geodesic currents. The lack of compactness requires the introduction of certain uniformity conditions which were unnecessary for compact surfaces. A technical step, providing a convergence result for earthquake paths in $\mathcal T…

Teichmüller空间上Thurston度量的包络

Envelopes of the Thurston metric on Teichmüller space

本文研究Teichmüller空间上Thurston度量的包络性质，通过谐波拉伸线定义包络结构，并探讨其连续性和可缩性，同时扩展到无限度量包络并提出新的特征化方法。

Some remarks on bounded earthquakes

We first show that an earthquake of a geometrically infinite hyperbolic surface induces an asymptotically conformal change in the hyperbolic metric if and only if the measured lamination associated with the earthquake is asymptotically trivial on the surface. Then we show that the contraction along earthquake paths is continuous in the Teichmüller space of any hyperbolic surface. Finally, we show that if a measured lamination vanishes while approaching infinity at the rate higher than the distance to the boundary then it must be trivial.