Submission date: 3 November 2020

Abstract:

We define good models of approximate subgroups and use them to study various classes of approximate subgroups. In particular, we show a closed-approximate-subgroup theorem, we extend to all amenable groups a structure theorem for mathematical quasi-crystals due to Meyer, and we prove a generalisation of theorems due to Auslander and Mostow about intersections of lattices and radicals of Lie groups.

Mathematics Subject Classification:

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Full text arXiv 2011.01829: pdf, ps.