Yulan Qing

Fudan University

Sublinearly Morse Boundary of Groups

Geometry and Topology Seminar

12th January 2021, 2:00 pm – 3:00 pm
Zoom seminar, if interested, please email one of the organisers to gain access to the Zoom link

Gromov boundary plays a central role in many aspects of geometric group theory. In this study, we develop a theory of boundary when the condition on hyperbolicity is removed: For a given proper, geodesic metric space X and a given sublinear function $\kappa$, we define the $\kappa$-boundary, as the space of all sublinearly-Morse quasi-geodesics rays. The sublinearly Morse boundary is QI-invariant and thus can be associated with the group that acts geometrically on X. For a large class of groups, we show that sublinearly Morse boundaries are large: they provide topological models for the Poisson boundaries of the group. This talk is based on several joint projects with Ilya Gekhtman, Kasra Rafi and Giulio Tiozzo.

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