All Fuchsian Schottky groups are classical Schottky groups

A sufficiently complicated noded Schottky group of rank three

The theoretical existence of non-classical Schottky groups is due to Marden. Explicit examples of such kind of groups are only known in rank two, the first one by by Yamamoto in 1991 and later by Williams in 2009. In 2006, Maskit and the author provided a theoretical method to obtain examples of non-classical Schottky groups in any rank. The method assumes the knowledge of some algebraic limits of Schottky groups, called sufficiently complicated noded Schottky groups, whose existence was stated. In this paper we provide an explicit construction of a sufficiently complicated noded Schottky grou…

经典 Schottky 群的收缩格扩张

Systolic lattice extensions of classical Schottky groups

本文构造了经典 Schottky 群的收缩格扩张，证明闭双曲流形收缩元实现的复平移长度具有稠密性，并给出构造非算术格的新方法。

Classical Two-parabolic T-Schottky groups

A $T$-Schottky group is a discrete group of Möbius transformations whose generators identify pairs of, possibly-tangent, Jordan curves on the complex sphere, ${\hat{\IC}}$. If the curves are Euclidean circles then the group is termed classical $T$-Schottky. We describe the boundary of the space of classical $T$-Schottky groups affording two parabolic generators within the larger parameter space of all $T$-Schottky groups with two parabolic generators. This boundary is surprisingly different from that of the larger space. It is analytic while the boundary of the larger space appears to be fract…

Kleinian groups of small Hausdorff dimension are classical Schottky groups I

In this paper we prove that there exists a positive number $λ>0$, such that any 2-generated Kleinian groups with limit set of Hausdorff dimension $<λ$ are classical Schottky groups.

A fake Schottky group in Mod(S)

We use the classical construction of Schottky groups in hyperbolic geometry to produce non-Schottky subgroups of the mapping class group.

Liouville action and Holography on quasi-Fuchsian deformation spaces

We study the Liouville action for quasi-Fuchsian groups with parabolic and elliptic elements. In particular, when the group is Fuchsian, the contribution of elliptic elements to the classical Liouville action is derived in terms of the Bloch-Wigner functions. We prove the first and second variation formulas for the classical Liouville action on the quasi-Fuchsian deformation space. We prove an equality expressing the holography principle, which relates the Liouville action and the renormalized volume for quasi-Fuchsian groups with parabolic and elliptic elements. We also construct the potentia…

All finitely generated Kleinian groups of small Hausdorff dimension are classical Schottky groups

This is the second part of the works on Hausdorff dimensions of Schottky groups. It has been conjectured that the Hausdorff dimensions of nonclassical Schottky groups are strictly bounded from below. In this second part of our works we provide a resolution of this conjecture, we prove that there exists a universal positive number $λ>0$, such that any finitely-generated non-elementary Kleinian groups with limit set of Hausdorff dimension $<λ$ are classical Schottky groups. We will generalize our previous technologies given in \cite{HS} to prove our general result. Our result can be consider as …

无限亏格的把手体与肖特基群

Handlebodies of Infinite Genus and Schottky Groups

本文通过定义展开对无限亏格把手体、无限生成肖特基群及单值化问题的研究，证明相关曲面和把手体的拓扑单值化、特定黎曼曲面的拟共形单值化及唯一性，并给出反例。

高维Schottky空间的拓扑

The topology of Schottky spaces in higher dimensions

研究高维Schottky空间的拓扑结构，主要定理表明在边界维数（两倍秩）时，空间的基本群是二阶循环群的乘积，但整体单连通，并证明旋转对称核是强形变收缩核。

长度谱的无理性

Irrationality of the Length Spectrum

本文给出非初等Fuchsian群长度谱无理性的初等证明，并证明存在两个长度在有理数上线性无关的元素，重证Prasad-Rapinchuk定理。

The classification of Kleinian groups of Hausdorff dimensions at most one and Burnside's conjecture

In this paper we provide the complete classification of convex cocompact Kleinian group of Hausdorff dimensions less than $1.$ In particular, we prove that every convex cocompact Kleinian group of Hausdorff dimension $<1$ is a classical Schottky group. This upper bound is sharp. The result implies that the converse of Burside's conjecture \cite{Burside} is true: All non-classical Schottky groups must have Hausdorff dimension $\ge1$. The prove of the theorem relies on the result of Hou \cite{Hou}.

Geodesic cusp excursions and metric diophantine approximation

We derive several results that describe the rate at which a generic geodesic makes excursions into and out of a cusp on a finite area hyperbolic surface and relate them to approximation with respect to the orbit of infinity for an associated Fuchsian group. This provides proofs of some well known theorems from metric diophantine approximation in the context of Fuchsian groups. It also gives new results in the classical setting.

The classification of Kleinian groups of Hausdorff dimensions at most one

In this paper we provide the complete classification of Kleinian groups of Hausdorff dimensions less than $1.$ In particular, we prove that every purely loxodromic Kleinian groups of Hausdorff dimension $<1$ is a classical Schottky group. This upper bound is sharp. As an application, the result of \cite{H} then implies that, every closed Riemann surface is uniformizable by a classical Schottky group. The prove relie on the result of Hou \cite{Hou}, and space of rectifiable $\G$-invariant closed curves.

Generalized Dedekind sums

Classical Dedekind sums are connected to the modular group through the construction of a (Dedekind) symbol on the cusp set of the modular group. In this paper we study generalizations of Dedekind symbols and sums that can be associated to certain Fuchsian groups uniformizing 1-punctured tori.

Triangle groups, automorphic forms, and torus knots

This paper's theme is the relation between several classical and well-known objects: triangle Fuchsian groups, quasi-homogeneous singularities of plane curves, torus knot complements in the 3-sphere. Torus knots are the only nontrivial knots whose complements admit transitive Lie group actions. In fact S^3\K_{p,q} is diffeomorphic to a coset space of the universal covering group of PSL_2(R) with respect to a discrete subgroup G contained in the preimage of a (p,q,\infty)-triangle Fuchsian group. The existence of such a diffeomorphism between is known from a general topological classification o…