We study a notion of "width" for Jordan curves in CP1, paying special attention to the class of quasicircles. The width of a Jordan curve is defined in terms of the geometry of its convex hull in hyperbolic three-space. A similar invariant in the setting of anti de Sitter geometry was used by Bonsante-Schle…
Characterizes quasiconformal homeomorphisms on surfaces.
problem Understanding the group of quasiconformal homeomorphisms on surfaces.
method Combinatorial characterization of quasiconformal homeomorphisms via graphs of essential quasicircles.
result Quasiconformal homeomorphisms are automorphisms of a graph of essential quasicircles on a surface.
We prove that the supremum of principal curvatures of a minimal embedded disc in hyperbolic three-space spanning a quasicircle in the boundary at infinity is estimated in a sublinear way by the norm of the quasicircle in the sense of universal Teichmüller space, if the quasicircle is sufficiently close to being the bou…
The paper proves properties of Bergman spaces and Schiffer operators on Riemann surfaces with quasicircles.
problem Properties of Bergman spaces and Schiffer operators on Riemann surfaces with quasicircles.
method Proof of isomorphism of Schiffer operators and application to Plemelj-Sokhotski isomorphism and jump decomposition.
result Schiffer integral operator is an isomorphism between Bergman spaces on different subsets of a Riemann surface.
Let R be a compact surface and let Γ be a Jordan curve which separates R into two connected components Σ1 and Σ2. A harmonic function h1 on Σ1 of bounded Dirichlet norm has boundary values H in a certain conformally invariant non-tangential sense on Γ. We show that if Γ is a quasicircle, then th…
The paper defines Benoist-Hulin groups and explores their properties.
problem Defining and characterizing Benoist-Hulin groups.
method Developing theory and proving properties of Benoist-Hulin groups.
result Uniform lattices and parabolic subgroups are Benoist-Hulin groups.
Celebrated work of Alexandrov and Pogorelov determines exactly which metrics on the sphere are induced on the boundary of a compact convex subset of hyperbolic three-space. As a step toward a generalization for unbounded convex subsets, we consider convex regions of hyperbolic three-space bounded by two properly embedd…
The universal Liouville action equals the renormalized volume of a hyperbolic 3-manifold.
problem Understanding the geometric significance of the universal Liouville action.
method Analyzing the Weil-Petersson universal Teichmüller space and its relation to hyperbolic 3-manifolds.
result The gradient flow of the universal Liouville action converges to the origin, providing a bound on Weil-Petersson distance.
The study examines uniqueness and non-uniqueness of minimal surfaces in hyperbolic space.
problem Uniqueness and non-uniqueness of minimal surfaces in hyperbolic space.
method Analyzes criteria for uniqueness and constructs examples of non-uniqueness.
result Uniqueness of minimal surfaces is equivalent to uniqueness in a smaller class of stable minimal disks.
The restricted class of quasicircles sometimes called the "Weil-Petersson-class" has been a subject of interest in the last decade. In this paper we establish a Sokhotski-Plemelj jump formula for WP-class quasicircles, for boundary data in a certain conformally invariant Besov space. We show that this Besov space is pr…
We consider properly discontinuous, isometric, convex cocompact actions of surface groups on a CAT(-1) space. We show that the limit set of such an action, equipped with the canonical visual metric, is a (weak) quasicircle in the sense of Falconer and Marsh. It follows that the visual metrics on such limit sets are cla…
Study Schiffer operators on Riemann surfaces, linking conformal and topological invariants.
problem Investigate Schiffer operators on Riemann surfaces and their connections to conformal and topological invariants.
method Develop calculus for Schiffer and Cauchy operators, derive index theorems, and characterize kernels and images.
result Derive index theorems for Schiffer operators, connecting conformal invariants to topological invariants.
The study characterizes quasiperiodic surfaces in pseudo-hyperbolic spaces with curvature conditions.
problem Characterizing quasiperiodic surfaces in pseudo-hyperbolic spaces.
method Curvature conditions, Gromov hyperbolicity, conformal hyperbolicity.
result Limit curves of quasiperiodic surfaces in the Einstein Universe have canonical quasisymmetric parametrizations.
The paper finds representations of surface groups in SO(4,1) with specific curvature properties.
problem Finding convex-cocompact representations of surface groups with minimal map properties.
method Complex variation of Hodge structures and embedded minimal maps.
result Examples of generalized almost-Fuchsian representations not deformations of Fuchsian representations.
Fixed points found in Teichmüller space via anti-de Sitter geometry.
problem Finding fixed points in Teichmüller space using earthquakes.
method Left earthquakes along measured laminations, using anti-de Sitter geometry.
result Composition of left earthquakes has a fixed point.
Study infinite circle patterns in the Weil-Petersson class using discrete harmonic functions.
problem Characterize infinite circle patterns in the Weil-Petersson class.
method Investigate circle patterns parameterized by discrete harmonic functions of finite Dirichlet energy, equipped with a Riemannian metric.
result Induced quasiconformal homeomorphisms from the unit disk to itself belong to the Weil-Petersson class.
Geometric data uniquely determines convex subsets in hyperbolic manifolds.
problem Determining convex subsets in hyperbolic manifolds based on boundary data.
method Using conformal structure, induced metric, and third fundamental form on boundary components.
result Convex subsets are uniquely determined by boundary data.
Unified approach to conformal and modular invariants on surfaces.
problem Constructing a general family of conformal invariants on surfaces.
method Using an identification of Teichmüller space and rigged moduli space, and analytic work on harmonic functions.
result Unified conformal and modular invariants can be viewed as generalized modular invariants and functions on the rigged moduli space.
The Weyl problem is extended to hyperbolic and anti-de Sitter spaces, connecting geometry, analysis, and group theory.
problem The classical Weyl problem for surfaces in hyperbolic and anti-de Sitter spaces.
method Generalizations of the Weyl problem to unbounded convex subsets and convex surfaces, focusing on thin and thick asymptotic boundaries.
result Connections to Kleinian groups, complex analysis, circle packings, and grafting on the hyperbolic disk.