Aug 2015

Brussels-London Geometry seminar, 3rd September 2015

The 7th Brussels—London Geometry Seminar has geometric group theory as its theme.  It will be held at UCL on Thursday, the 3rd of September, and the schedule is as follows.

11am: Javier Aramayona. Madrid, Spain.
“The abelianization of automorphism groups of right-angled Artin groups.”
Automorphism groups of right-angled Artin groups form an interesting class of groups, as they interpolate between the two extremal cases of Aut(F_n) and GL(n,Z). In this talk we will discuss some conditions on a simplicial graph which imply that the automorphism group of the associated right-angled Artin group has (in)finite abelianization. As a direct consequence, we obtain families of such automorphism groups that do not have Kazhdan's property (T). This is joint work with Conchita Martinez-Perez.

2pm Pierre Py. Strasbourg, France.
“Coherence and fundamental groups of complex surfaces.”
A group is called coherent if all its finitely generated subgroups are finitely presented. I will describe a theorem due to Kapovich which provides a criterion for the fundamental group of a complex surface to be (in)coherent. Based on this criterion, we prove that certain Dehn fillings of non-uniform complex hyperbolic lattices are incoherent. .

3.30pm Karen Vogtmann. Warwick, UK.
“Outer space for right-angled Artin groups.”
Automorphism groups of right-angled Artin groups generalize both GL(n,Z) and Out(F_n). Together with Ruth Charney we are developing an “outer space” which generalizes both the symmetric space for GL_n and the Outer space of a free group. I will discuss the current state of this project.