24.05.22

Sam Hughes (University of Oxford)

Title

Irreducible lattices fibring over the circle

Abstract

Let n≥2 and let Λ be a lattice in a product of simple non-compact Lie groups with finite centre. An application of the Margulis Normal Subgroup Theorem implies that if H¹(Λ) is non-zero, then Λ is reducible. In the more general CAT(0) setting there are many irreducible lattices with non-vanishing first cohomology. In this case we can deploy the BNSR invariants and investigate how far these cohomology classes are from a fibration of finite type CW complexes. In this talk we will combine the groups of Leary and Minasyan with the technology of Bestvina and Brady to construct the first examples of irreducible lattices which fibre over the circle.

Schedule

10:00 - 11:30 RTG Lecture 1 (Max Riestenberg), SR 2.058

11:30 - 12:00 Get-Together with speaker, SR2.058

12:00 - 13:00 Common lunch

13:00 - 13:30 Informal meeting of PhD students, Topologischer Raum

13:45 - 14:45 RTG colloquium: Sam Hughes, SR. 1067

14:45 - 15:30 Common tea, Faculty meeting room 1.058

15:30 - 17:00 RTG Lecture 3 (Alexander Lytchak), SR 1.067

KIT