Thomas Haettel

Thomas Haettel is a Senior Lecturer at the University of Montpellier and IUT Montpellier-Sète since 2013. He is a Junior member of the Institut Universitaire de France (IUF) for 2025-2030. His academic affiliation spans the Faculty of Science's Department of Mathematics, where he contributes to research and teaching.

His research focuses on geometric group theory, specifically group actions on nonpositively curved spaces. Key areas include:

• Combinatorial nonpositive curvature (CAT(0) cube complexes, Helly graphs, Garside categories)
• Coarse nonpositive curvature (hierarchically hyperbolic spaces, coarse median spaces)
• Continuous nonpositive curvature (symmetric spaces, Teichmüller spaces, injective metric spaces)
• Braid groups and Artin-Tits groups
• Mapping class groups and surface fundamental groups

His article analysis reveals:

• Geometric rigidity of higher rank lattices
• Injective metric structures in buildings and symmetric spaces
• New Garside theory applications
• Proper affine actions on Lp spaces
• Horofunction compactifications
• Automorphism classifications in Helly graphs

Awards:

• IUF Junior membership
• HDR (Habilitation à Diriger les Recherches) 2021

He supervises PhD students in geometric group theory and has held visiting positions at CRM Montréal, EPFL, and Princeton University.