Bielefeld-Münster Seminar
on Groups, Geometry and Topology

Date: January 17, 2020

Venue: Bielefeld University

The talks will take place in V2-210. Coffee will be served in the same room during the coffee breaks.

Schedule

10:00 UhrDawid Kielak
Fibring of manifolds and groups
11:00 UhrCoffee break
11:30 UhrHerbert Abels
Dense sub(semi)groups of Lie groups
12:30 UhrLunch break
14:00 UhrJosh Maglione
Isomorphism of nilpotent groups via derivations
15:00 UhrCoffee break
15:30 UhrGiles Gardam
Leighton's theorem
16:30 UhrEnd the of seminar

Abstracts

Dawid Kielak

Fibring of manifolds and groups

I will discuss how one can use a little group homology to reprove and generalise statements about 3-manifolds fibring over the circle.

Herbert Abels

Dense sub(semi)groups of Lie groups

I am planning to present the recent joint result with E.B. Vinberg on dense subsemigroups of nilpotent Lie groups. I will put it into the context of other results and questions on dense sub(semi)groups of Lie groups. And I will explain why the question of density is the wrong question.

Josh Maglione

Isomorphism of nilpotent groups via derivations

By bringing in tools from multilinear algebra, we introduce a general method to aid in the computation of isomorphism for groups. Of particular interest are nilpotent groups where the only classically known proper nontrivial characteristic subgroup is the derived subgroup. This family of groups poses the biggest challenge to all modern approaches. Through structural analysis of the bi-additive commutator map, we leverage the representation theory of Lie algebras to prove efficiency for families of nilpotent groups. We report on joint work with Peter A. Brooksbank, Uriya A. First,and James B. Wilson.

Giles Gardam

Leighton's theorem

Leighton proved that any two finite graphs with the same universal cover have a common finite-sheeted cover. I will present a strengthening of this theorem proved in joint work with Daniel Woodhouse and independently by Sam Shepherd.

Last modified: Thu 26 Mar 2020, 08:45