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Giles Gardam

GGT Seminar: Tim de Laat (Münster): Origami expanders

Thursday, 20.01.2022 15:00 im Raum SRZ 216/217

Mathematik und Informatik

We construct a new type of expanders, from measure-preserving affine actions with spectral gap on origami surfaces, in each genus g > 0. These actions are the first examples of actions with spectral gap on surfaces of genus g > 1. We prove that the new expanders are coarsely distinct from the classical expanders obtained via the Laplacian as Cayley graphs of finite quotients of a group. In genus g = 1, this implies that the Margulis expander, and hence the Gabber-Galil expander, is coarsely distinct from the Selberg expander. This is joint work with Goulnara Arzhantseva, Dawid Kielak and Damian Sawicki.



Angelegt am 19.11.2021 von Giles Gardam
Geändert am 19.01.2022 von Giles Gardam
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