Talks and events


Upcoming talks

[oberseminar] Wed 17.10.2018, Math II (Lonza) at 10h20

Alexander Rahm (University of Luxembourg): Hyperbolic orbifolds and their twisted sectors

An especially nice family of hyperbolic orbifolds, which is of particular interest in number theory, are the Bianchi orbifolds, which arise from the action of the Bianchi groups - namely the SL_2 matrix groups over imaginary quadratic rings of integers - on hyperbolic 3-space (which is their associated symmetric space). The Bianchi groups are prototypical for groups of hyperbolic motions linking to number theory, because each non-cocompact arithmetic Kleinian group is commensurable with some Bianchi group.
When we complexify hyperbolic 3-space, we obtain complexified Bianchi orbifolds, whose Chen-Ruan orbifold cohomology ring was conjectured by Ruan to be isomorphic to the cohomology ring of a crepant resolution for the complexified orbifold, which makes it interesting for mathematical string theory. This conjecture has been proven by Fabio Perroni and the speaker.
In this talk, we will look into the computation of the sectors of the Chen-Ruan orbifold cohomology which made this proof possible. For its non-twisted sector, software has been developed which constructs fundamental domains for the action of the Bianchi groups, and hence determines the orbit space. And for its twisted sectors, there is a technique of the speaker, called Torsion Subcomplex Reduction, which allows to produce formulas for the cohomological torsion; we will look into how this allows to control the centralizer quotients which constitute the twisted sectors.

[colloque] Tue 4.12.2018, Phys 2.52 at 17h15

Prof. Bernard Ries (Uni Fribourg): tba

[colloque] Tue 11.12.2018, Phys 2.52 at 17h15

Prof. Christoph Thäle (Ruhr-Universität Bochum): tba


Colloquia in the current semester

[colloque] Tue 20.2.2018, Phys 2.52 at 17h15more

Prof. Alexandre Stauffer (University of Bath): Spatial growth processes: dendritic formation and competition

[colloque] Tue 6.3.2018, Phys 2.52 at 17h15more

Prof. Jan Maas (IST Austria): Gradient flows and optimal transport in discrete and quantum systems

[colloque] Tue 13.3.2018, Phys 2.52 at 17h15more

Prof. Florian Bertrand (American University of Beirut): Invariant metrics in complex analysis

[colloque] Tue 20.3.2018, Phys 2.52 at 17h15more

Prof. Jean-Marc Schlenker (Luxembourg): Polyhedra inscribed in quadrics

[colloque] Tue 10.4.2018, Phys 2.52 at 17h15more

Prof. Pierre Pansu (Université Paris-Sud Orsay): Large scale conformal geometry

[colloque] Tue 8.5.2018, Phys 2.52 at 17h15more

Prof. Luis Guijarro (Universidad Autónoma de Madrid): The transverse Jacobi equation for geodesics

[colloque] Tue 15.5.2018, Phys 2.52 at 17h15 more

Prof. Andrea Mondino (Warwick): Smooth and non-smooth aspects of Ricci curvature lower bounds

[colloque] Tue 22.5.2018, Phys 2.52 at 17h15more

Prof. Stéphane Loisel (ISFA Lyon): Reevaluation of the capital charge in insurance after a large shock: empirical and theoretical views

[colloque] Tue 29.5.2018, Phys 2.52 at 17h15more

Prof. Aleksandr Kolpakov (Uni Neuchâtel): Super-exponential families of hyperbolic manifolds

Other talks and events in the current semester

[oberseminar] Oberseminar Geometrie, Tue 13.02.2018, Math II (Lonza) at 10h20more

Arielle Leitner (Technion): Generalized cusps on convex projective manifolds

[oberseminar] Oberseminar Geometrie, Wed 21.02.2018, Math II (Lonza) at 10h20more

Corina Ciobotaru (Fribourg): Applications of hyperbolic geometry to Kuramoto model of synchronization

[oberseminar] Informal Analysis Seminar, Tue 27.02.2018, Seminar room 0.102, at 10:15more

Kevin Wildrick: The theory of Newton-Sobolev mappings

[oberseminar] Oberseminar Geometrie, Wed 28.02.2018, Math II (Lonza) at 10h20more

Cesar Ceballos (University of Vienna): Combinatorics and Geometry of v-Tamari lattices

[oberseminar] Geometric Analysis Seminar, Fri 02.03.2018, Science de la Terre 1.309, at 14:15more

Changyu Guo (Fribourg): Theory of p-harmonic mappings: progress and open problems

[oberseminar] Combinatorics Seminar, Wed 7.3.2018, Math II (Lonza) at 14h00more

Enrico Cecini (Genoa): Matroid structures in Graph Signal Processing

[oberseminar] Oberseminar Geometrie, Wed 07.03.2018, Math II (Lonza) at 10h20more

Thibaut Dumont (Jyväskylä): Growth of the volume cocycle in Euclidean buildings

[oberseminar] Oberseminar Topologie, Mon 12.03.2018, Math II (Lonza) at 16h00 more

Uwe Semmelmann (Stuttgart): The kernel of the Rarita-Schwinger operator on Riemannian spin manifolds

[oberseminar] Oberseminar Topologie, Monday 19.03.2018, Math II (Lonza) at 16h00more

Jan-Bernhard Kordass (Karlsruhe): Spaces of Riemannian Metrics satisfying Surgery Stable Curvature Conditions

[oberseminar] Combinatorics Seminar, Wed 21.3.2018, Math II (Lonza) at 14h00more

Viola Siconolfi (Roma): Wonderful models for generalized Dowling lattices

[oberseminar] Oberseminar Geometrie, Wed 21.03.2018, Math II (Lonza) at 10:20more

Roman Prosanov (Fribourg): From cusped hyperbolic surfaces to convex ideal Fuchsian polyhedra

[oberseminar] Oberseminar Topologie, Monday 26.03.2018, Math II (Lonza) at 16h00more

Raphael Zentner (Regensburg/FIM): Irreducible SL(2,C)-representations of integer homology 3-sphere

[oberseminar] Oberseminar Geometrie, Wed 28.03.2018, Math II (Lonza) at 10:20more

Kurt Falk (Kiel): Dimension gaps for limit sets of Kleinian groups

[oberseminar] Oberseminar Geometrie, Wed 11.04.2018, Math II (Lonza)more

Olivier Mila (Bern): Nonarithmetic hyperbolic manifolds and trace rings

[oberseminar] Oberseminar Geometrie, Wed 18.04.2018, Math II (Lonza)more

Stefano Riolo (Neuchatel): Growth of geometrically bounding hyperbolic 3-manifolds

[oberseminar] Oberseminar Geometrie, Wed 02.05.2018, Math II (Lonza) at 10h20more

Ivan Izmestiev (Fribourg): Flexible Kokotsakis polyhedra

[oberseminar] Oberseminar Topologie, Thursday 03.05.2018, Math II (Lonza) at 15h00more

Wilderich Tuschmann (Karlsruhe, KIT): Nikolaev manifolds and Alexandrov metrics

[oberseminar] Geometric Analysis Seminar, Fri 04.05.2018, Sciences de la Terre, room 1.309, at 14:15more

Thomas Mettler (Goethe-Universitaet Frankfurt): The Beltrami differential revisited

[oberseminar] Oberseminar Topologie, Monday 07.05.2018, Math II (Lonza) at 16h00more

Mauricio Bustamante (Augsburg): Bundles with fiberwise negatively curved metrics

[oberseminar] Geometric Analysis Seminar, Tue 08.05.2018, Physics 2.52, at 10:15more

Hubert Sidler (University of Fribourg): Harmonic quasi-isometric maps into Gromov hyperbolic CAT(0)-spaces

[oberseminar] Oberseminar Geometrie, Wed 09.05.2018, Math II (Lonza) at 10h20more

Christoforos Neofytidis (Geneva): Aspherical circle bundles and a problem of Hopf

[oberseminar] Geometric Analysis Seminar, Tue 15.05.2018, Physics 2.52, at 10:15more

Andrea Mondino (Warwick): Geometric and functional inequalities via a 1-dimensional localisation method

[oberseminar] Oberseminar Geometrie, Wed 16.05.2018, Math II (Lonza) at 10h20more

Edoardo Dotti (Fribourg): Classification of Hyperbolic Coxeter Groups

[oberseminar] Geometric Analysis Seminar, Fri 18.05.2018, Science de la Terre 1.309, at 14:15more

Tomasz Adamowicz (Warsaw): Mean-value harmonic functions

[oberseminar] Geometric Analysis Seminar, Fri 25.05.2018, place TBA, at 14:15more

Roger Züst (University of Bern): TBA

[oberseminar] Oberseminar Geometrie, Tue 29.05.2018, Math II (Lonza) at 13h15more

Matthieu Jacquemet (HES-SO Valais (Sion) and University of Fribourg): Computational aspects of the classification of hyperbolic Coxeter polyhedra

Université de Fribourg - Mathématiques - Ch. du Musée 23, 1700 Fribourg - tél +41 26 / 300 9180
Last modified on Mar 5, 2018    Webmasters: Sophie Schneider, Simon Drewitz