C˜2 lattices with no subgroups of finite index

by Thomas Titz Mite (JLU Giessen)

Tuesday 28 Jan 2025, 11:00 → 12:00 Europe/Brussels

B/2nd floor-B.203 - Seminar room (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

We construct uniform lattices on C˜2  buildings, that have no proper subgroups of finite index. In particular these lattices are not residually finite. Conjecturally the normal subgroup theorem extends to these lattices making them abstractly simple. We discuss the construction and properties of these lattices and the buildings they act on. This is joint work with Stefan Witzel.