Ursula Hamenstādt

activity

20052026

collaborators

17 papers

math.GT2026

The geometry of branched coverings of hyperbolic manifolds

Ursula Hamenstädt

We discuss geometric properties of covers of closed hyperbolic manifolds of dimension $n \geq 3$ , branched along a totally geodesic codimension two submanifold $Σ$ . The results are…

math.DS2025

Exponential mixing of the Teichmüller flow on affine invariant manifolds

Ursula Hamenstädt

Let S be a non-exceptional oriented surface of finite type. We give a new proof based on symbolic coding of the following result of Avila and Gouezel. The Teichmueller flow is expo…

math.DG2025

Hitchin grafting representations I: Geometry

Pierre-Louis Blayac, Ursula Hamenstädt, Théo Marty

We give a geometric interpretation of Fock--Goncharov positivity and show that bending deformations of Fuchsian representations stabilize a uniform Finsler quasi-convex disk in the…

math.DG2025

Kähler-Einstein metrics of negative curvature

Henri Guenancia, Ursula Hamenstädt

Given any integer $n \geq 2$ , we construct a compact Kähler-Einstein manifold of dimension n of negative sectional curvature which is not covered by the ball.

math.DG2024

Negatively curved Einstein metrics on Gromov-Thurston manifolds

Ursula Hamenstädt, Frieder Jäckel

For every $n \geq 4$ we construct infinitely many mutually not homotopic closed manifolds of dimension $n$ which admit a negatively curved Einstein metric but no locally symmetric m…

math.DG2024

Hitchin grafting representations II: Dynamics

Pierre-Louis Blayac, Ursula Hamenstädt, Théo Marty +1

The Hitchin component of the character variety of representations of a surface group $π_{1} (S)$ into $PSL_{d} (R)$ for some $d \geq 3$ can be equipped with a pressure…

math.GT2024

Submanifold projections and hyperbolicity in $Out (F_{n})$

Ursula Hamenstädt, Sebastian Hensel

The free splitting graph of a free group $F_{n}$ with $n \geq 2$ generators is a hyperbolic $Out (F_{n})$ -graph which has a geometric realization as a sphere graph in the connected…

math.GR2023

$L^{p}$ -cohomology for groups of isometries of Hadamard spaces

Ursula Hamenstädt

We show that a discrete group $Γ$ which admits a non-elementary isometric action on a Hadamard manifold of bounded negative curvature admits an isometric action on an $L^{p}$ -space $…

math.GR2023

Actions of finitely generated groups on compact metric spaces

Ursula Hamenstädt

Let $Γ$ be a finitely generated group which admits an action by homeomorphisms on a compact metrizable space $X$ . We show that there is a metric on $X$ defining the original topolo…

math.DG2022

Stability of Einstein metrics and effective hyperbolization in large Hempel distance

Ursula Hamenstädt, Frieder Jäckel

Extending earlier work of Tian, we show that if a manifold admits a metric that is almost hyperbolic in a suitable sense, then there exists an Einstein metric that is close to the…

math.GT2021

Spotted disk and sphere graphs I

Ursula Hamenstädt

The disk graph of a handlebody H of genus g at least 2 with m marked points on the boundary is the graph whose vertices are isotopy classes of disks disjoint from the marked points…

math.GT2020

Signature of surface bundles and bounded cohomology

Ursula Hamenstädt

Extending a result of Morita, we show that all tautological classes of the moduli space of genus g curves are bounded. As an application, we obtain that for a surface bundle $E\to…

math.GR2018

The Geometry of the Handlebody Groups II: Dehn functions

Ursula Hamenstädt, Sebastian Hensel

We show that the Dehn function of the handlebody group is exponential in any genus $g \geq 3$ . On the other hand, we show that the handlebody group of genus $2$ is cubical, biautoma…

math.DS2011

Symbolic dynamics for the Teichmueller flow

Ursula Hamenstädt

Let Q be a component of a stratum of abelian or quadratic differentials on an oriented surface of genus $g \geq 0$ with $m \geq 0$ punctures and $3 g - 3 + m \geq 2$ . We construct a subshi…

math.GT2011

Isoperimetric inequalities for the handlebody groups

Ursula Hamenstädt, Sebastian Hensel

We show that the mapping class group of a handlebody of genus at least 2 has a Dehn function of at most exponential growth type.

math.DS2009

Dynamical properties of the Weil-Petersson metric

Ursula Hamenstadt

Let S be a non-exceptional oriented surface of finite type. We discuss the action of subgroups of the mapping class group of S on the CAT(0)-boundary of the completion of Teichmuel…

math.GR2005

Isometry groups of proper hyperbolic spaces

Ursula Hamenstadt

Let X be a proper hyperbolic geodesic metric space and let G be a closed subgroup of the isometry group Iso(X) of X. We show that if G is not amenable then its second continuous bo…

The geometry of branched coverings of hyperbolic manifolds

Exponential mixing of the Teichmüller flow on affine invariant manifolds

Hitchin grafting representations I: Geometry

Kähler-Einstein metrics of negative curvature

Negatively curved Einstein metrics on Gromov-Thurston manifolds

Hitchin grafting representations II: Dynamics

Submanifold projections and hyperbolicity in Out(Fn​)

Lp-cohomology for groups of isometries of Hadamard spaces

Actions of finitely generated groups on compact metric spaces

Stability of Einstein metrics and effective hyperbolization in large Hempel distance

Spotted disk and sphere graphs I

Signature of surface bundles and bounded cohomology

The Geometry of the Handlebody Groups II: Dehn functions

Symbolic dynamics for the Teichmueller flow

Isoperimetric inequalities for the handlebody groups

Dynamical properties of the Weil-Petersson metric

Isometry groups of proper hyperbolic spaces

Submanifold projections and hyperbolicity in $Out (F_{n})$

$L^{p}$ -cohomology for groups of isometries of Hadamard spaces