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Spring Semester 2026

Date / Time Speaker Title Location
26 March 2026
16:00-17:00 		Yan Luo
ETH Zürich
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Geometry Graduate Colloquium

Title Renormalized volume and Weil Petersson Teichmüller space
Speaker, Affiliation Yan Luo, ETH Zürich
Date, Time 26 March 2026, 16:00-17:00
Location HG G 19.2
Abstract In this talk, we introduce the notion of renormalized volume of convex cocompact 3-manifolds. Using the normal geodesic flow associated with a equidistant foliation, the renormalized volume can be related to the conformal structure of the boundary at infinity of the manifold. Thus it can be realized as a functional on the Teichmüller space of the boundary at infinity, and by method of variation, as a Kähler potential for the Weil-Petersson metric. We also discuss some recent work which defined the renormalized volume of quasicircles in the Riemann sphere. In this setting, the renormalized volume has parallel properties, and is equal to the universal Liouville action (Loewner energy) of curves with certain regularity.
Renormalized volume and Weil Petersson Teichmüller space read_more
HG G 19.2
16 April 2026
16:00-17:00 		Dr. Damaris Meier
ETH Zurich, Switzerland
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Geometry Graduate Colloquium

Title Monotne Sobolev extensions in metric surfaces
Speaker, Affiliation Dr. Damaris Meier, ETH Zurich, Switzerland
Date, Time 16 April 2026, 16:00-17:00
Location HG G 43
Abstract Every monotone Lipschitz map from the circle into the Euclidean plane admits a monotone Lipschitz extension to the disc. This property generally fails for non-smooth metric surface targets. However, by passing to the slightly larger class of Sobolev mappings, one can prove an analogous extension result. In this talk, we show how such extensions can be constructed using a suitable collar construction combined with energy minimization techniques.
Monotne Sobolev extensions in metric surfacesread_more
HG G 43
23 April 2026
16:00-17:00 		Daniel Meriaz
University of Bristol
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Geometry Graduate Colloquium

Title Quantum chaos and geometry of large hyperbolic surfaces
Speaker, Affiliation Daniel Meriaz, University of Bristol
Date, Time 23 April 2026, 16:00-17:00
Location HG G 43
Abstract Quantum chaos is the study of spectral data of classically chaotic systems. Key objects of study are the eigenvalues and eigenfunctions of the laplacian on hyperbolic surfaces. Recently, large-scale quantum chaos-type results have garnered considerable interest. In this talk, we aim to give an introduction to this field, and some of its tools. In ongoing work, we provide a new insight into the shapes of short geodesic loops on surfaces, which, in particular, can be applied to the study of eigenfunctions in the large-scale regime.
Quantum chaos and geometry of large hyperbolic surfacesread_more
HG G 43
30 April 2026
16:00-17:00 		Letizia Issini
Université de Genève
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Geometry Graduate Colloquium

Title Divergence in groups with micro-supported actions
Speaker, Affiliation Letizia Issini, Université de Genève
Date, Time 30 April 2026, 16:00-17:00
Location HG G 43
Abstract Divergence of groups is a quasi-isometry invariant that measures how difficult it is to connect two points while avoiding a large ball around the identity. It is easy to see that divergence is linear for direct products. I will discuss how the presence of direct products as subgroups can be used to show that certain groups have linear divergence. This applies to some groups that admit a micro-supported action on a Hausdorff topological space, i.e., groups containing elements with arbitrarily small support. Joint work in progress with D. Francoeur and T. Nagnibeda
Divergence in groups with micro-supported actionsread_more
HG G 43
* 21 May 2026
13:00-14:15 		María Jimenez Vazquez
ETH Zurich
Details

Geometry Graduate Colloquium

Title Symmetries and representations of groupoids.
Speaker, Affiliation María Jimenez Vazquez, ETH Zurich
Date, Time 21 May 2026, 13:00-14:15
Location HG G 43
Abstract In many situations, when a global symmetry is restricted to a subspace, we lose the group action, but a residual symmetry remains visible. In this talk, I will illustrate how groupoids address this issue and explain why they are the most suitable mathematical objects for describing symmetries. I will then define linear representations of groupoids and prove a theorem establishing a one-to-one correspondence between representations of groupoids and representations of their isotropy groups. Joint work with prof. Alberto Ibort and prof. Juan Manuel Perez-Pardo.
Symmetries and representations of groupoids.read_more
HG G 43
28 May 2026
16:00-17:00 		Martina Bellettini
University of Trento
Details

Geometry Graduate Colloquium

Title Decomposition of normal currents
Speaker, Affiliation Martina Bellettini, University of Trento
Date, Time 28 May 2026, 16:00-17:00
Location HG G 43
Abstract I will review some well-known results and examples on the decomposition of normal currents into rectifiable currents, both for one-dimensional currents and for currents of codimension one. In the second part of the talk, I will outline an example due to A. Schioppa of a normal 2-current supported on a purely 2-unrectifiable set, presenting an alternative proof. Based on joint work with G. Alberti and A. Marchese.
Decomposition of normal currentsread_more
HG G 43

Notes: events marked with an asterisk (*) indicate that the time and/or location are different from the usual time and/or location.

Organisers: Konstantin Andritsch, Segev Gonen Cohen, Yuriy Tumarkin

Archive: AS 26 SS 26 AS 25 SS 25 AS 24 SS 24 AS 23 SS 23 AS 22 SS 22 AS 21 SS 21 AS 20 SS 20 AS 19 AS 18 SS 18

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