4 papers · 1 filter
Higher finiteness properties of arithmetic approximate lattices: The Rank Theorem for number fields
Tobias Hartnick, Stefan Witzel
We introduce geometric and homological finiteness properties for countable approximate groups via coarse geometry and then study these finiteness properties for S-arithmetic reduct…
Hyperbolic generalized triangle groups, property (T) and finite simple quotients
Pierre-Emmanuel Caprace, Marston Conder, Marek Kaluba +1
We construct several series of explicit presentations of infinite hyperbolic groups enjoying Kazhdan's property (T). Some of them are significantly shorter than the previously know…
Boundary Braids
Michael Dougherty, Jon McCammond, Stefan Witzel
The n-strand braid group can be defined as the fundamental group of the configuration space of n unlabeled points in a closed disk based at a configuration where all n points lie i…
The Basilica Thompson group is not finitely presented
Stefan Witzel, Matthew C. B. Zaremsky
We show that the Basilica Thompson group introduced by Belk and Forrest is not finitely presented, and in fact is not of type FP_2. The proof involves developing techniques for pro…