Holomorphic quadratic differentials dual to Fenchel–Nielsen coordinates
Große, N Rupflin, M Annals of Global Analysis and Geometry volume 55 issue 3 479-507 (16 Apr 2019)

90% of the world’s data have been generated in the last five years. A small fraction of these data is collected with the aim of validating specific hypotheses. These studies are led by the development of mechanistic models focussed on the causality of input-output relationships. However, the vast majority of the data are aimed at supporting statistical or correlation studies that bypass the need for causality and focus exclusively on prediction.

Wed, 13 Jun 2018

16:00 - 17:00
C5

The l1-homology of one-relator groups

Nicolaus Heuer
(University of Oxford)
Abstract

We will study the l1-homology of the 2-class in one relator groups. We will see that there are many qualitative and quantitive similarities between the l1-norm of the top dimensional class and the stable commutator length of the defining relation. As an application we construct manifolds with small simplicial volume.

This work in progress is joint with Clara Loeh.

Thu, 14 Jun 2018

16:00 - 17:00
L6

O-minimality and Cox rings over number fields for Manin’s conjecture

Ulrich Derenthal
(Leibniz Universität Hannover)
Abstract

Manin’s conjecture predicts the asymptotic behavior of the number of rational points of bounded height on Fano varieties over number fields. We prove this conjecture for a family of nonsplit singular quartic del Pezzo surfaces over arbitrary number fields. For the proof, we parameterize the rational points on such a del Pezzo surface by integral points on a nonuniversal torsor (which is determined explicitly using a Cox ring of a certain type), and we count them using a result of Barroero-Widmer on lattice points in o-minimal structures. This is joint work in progress with Marta Pieropan.

Tue, 12 Jun 2018

15:00 - 16:15
C2

Subriemannian metrics and the metrizability of parabolic geometries

Prof Jan Slovak
(Brno)
Abstract

We present the linearized metrizability problem in the context of parabolic geometries and subriemannian geometry, generalizing the metrizability problem in projective geometry studied by R. Liouville in 1889. We give a general method for linearizability and a classification of all cases with irreducible defining distribution where this method applies. These tools lead to natural subriemannian metrics on generic distributions of interest in geometric control theory.

Fri, 15 Jun 2018

15:00 - 16:00
L6

"A counterexample to the first Zassenhaus conjecture".

Florian Eisele
(City University London)
Abstract

There are many interesting problems surrounding the unit group U(RG) of the ring RG, where R is a commutative ring and G is a finite group. Of particular interest are the finite subgroups of U(RG). In the seventies, Zassenhaus conjectured that any u in U(ZG) is conjugate, in the group U(QG), to an element of the form +/-g, where g is an element of the group G. This came to be known as the "(first) Zassenhaus conjecture". I will talk about the recent construction of a counterexample to this conjecture (this is joint work with L. Margolis), and recent work on related questions in the modular representation theory of finite groups.

Tue, 12 Jun 2018

12:45 - 13:30
C5

Scalable Least-Squares Minimisation for Bundle Adjustment Problems

Lindon Roberts
Abstract

Structure from Motion (SfM) is a problem which asks: given photos of an object from different angles, can we reconstruct the object in 3D? This problem is important in computer vision, with applications including urban planning and autonomous navigation. A key part of SfM is bundle adjustment, where initial estimates of 3D points and camera locations are refined to match the images. This results in a high-dimensional nonlinear least-squares problem. In this talk, I will discuss how dimensionality reduction methods such as block coordinates and sketching can be used to improve solver scalability for bundle adjustment problems.

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