KU-SDU Operator algebras seminar

Speaker: Damian Osajda (University of Wroclaw)

Title: Helly groups

Abstract: A simplicial graph is Helly if each family of pairwise intersecting (combinatorial) balls has non-empty intersection. Group acting geometrically on such graphs are themselves called Helly. The family of such groups is vast, it contains: Gromov hyperbolic groups, CAT(0) cubical groups, Garside groups, FC type Artin groups, some lattices in buildings, and others. On the other hand, being Helly implies many important algorithmic and geometric features of the group. In particular, such groups act geometrically on spaces with convex geodesic bicombing, equipping them with a kind of CAT(0)-like structure. One immediate consequence is that Helly groups satisfy the coarse Baum-Connes conjecture and the Farrell-Jones conjecture, allowing us to prove these conjectures for new classes of groups.

I will present basic properties and examples of Helly groups. The talk is based on joint works with Jeremie Chalopin, Victor Chepoi, Anthony Genevois, Hiroshi Hirai, Jingyin Huang, Motiejus Valiunas, Thomas Haettel.

Zoom link: https://syddanskuni.zoom.us/j/67427295726?pwd=TlQ4NEY2a0RMcEpld2hDaUt3YmhLdz09

Zoom ID: 674 2729 5726

Password: OANCG