Jean-Morlet chair - GENEVIEVE WALSH - LUISA PAOLUZZI (semester 1, 2018)
This workshop aims to address the following topics regarding the boundaries of hyperbolic, relatively hyperbolic and CAT(0) groups.
Cannon’s Conjecture and related conjectures: If a torsion-free hyperbolic group group has boundary at infinity a 2-sphere, must the group be a lattice in SO(3, 1)? This is one of the remaining outstanding problems in 3-dimensional topology. Some related work was done by Kapovich-Kleiner (boundary a Sierpinski carpet). Higher dimensional topological analogues are known (Bartels-Lück-Reich, Lafont-Tshishiku).
Relation to QIs: In some cases, properties of the boundary can be used to “fill in” and obtain rigidity results about spaces. For example Bonk-Schramm related the existence of bi-Lipschitz homeomorphism of boundaries to the existence of almost-isometries between spaces.
CAT(0) boundaries: A famous example of Croke-Kleiner shows that the boundary at infinity of a CAT(0) space is not a QI-invariant. However, recent work of Charney- Sultan shows that certain subsets of the boundary are QI-invariant. Are there other naturally definite subsets of the boundary that are QI-invariant?
Boundaries of Hyperbolic Buildings: These provide an important testing ground for studying metric properties of the boundary.
Relatively hyperbolic groups: What is the “best” boundary for a relatively hyperbolic group? The boundary of the hyperbolic space on which the group acts geometrically finitely (known as the Bowditch boundary)? A CAT(0) type boundary? Is there a way to put a quasi-conformal structure that is meaningful on either of these boundaries?
Rigidity: What group theoretical information can be obtained
from the topology of the boundary?
Note that this event is only open to participants who have received an invitation from the organizers. The Events Officer will take care of Pre-registrations.
Preliminary list of Speakers
NB: In accordance with the Statement of Inclusiveness (http://www.math.toronto.edu/~rafi/statement/) this event will be open to everybody, regardless of race, sex, religion, national origin, sexual orientation, gender identity, disability, age, pregnancy, immigration status, or any other aspect of identity.