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Durham University

Department of Mathematical Sciences

Seminar details

Geometry and Topology Seminar: Amorphic complexity (of group actions)

Presented by Gabriel Fuhrmann, Durham University

14 January 2021 13:05 in Zoom.

Amorphic complexity is a conjugacy invariant which is particularly suitable to distinguish low complexity (specifically: zero entropy) dynamical systems. Here, a dynamical system is understood as a continuous action of a topological group on a compact space. We will introduce amorphic complexity (as well as the closely related concept of asymptotic separation numbers) and discuss some of its basic properties. We further take a closer look at its values for specific classes of examples including substitutive subshifts and, if time allows, regular cut and project schemes. This will allow us to observe surprisingly straight-forward connections to fractal geometry. I will provide definitions of all of the relevant non-standard notions so that the talk should be understandable by a broad audience.

This is joint work with Maik Gröger, Tobias Jäger and Dominik Kwietniak (carried out by three different subsets of the four of us).

The talk will be online. A Zoom invitation will be sent on Wednesday before the seminar.

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