Hall’s universal group is a subgroup of the abstract commensurator of a free group

Publication Date

1-1-2023

Document Type

Article

Publication Title

Israel Journal of Mathematics

DOI

10.1007/s11856-023-2591-8

Abstract

P. Hall constructed a universal countable locally finite group U, determined up to isomorphism by two properties: every finite group C is a subgroup of U, and every embedding of C into U is conjugate in U. Every countable locally finite group is a subgroup of U. We prove that U is a subgroup of the abstract commensurator of a finite-rank nonabelian free group.

Funding Sponsor

Azrieli Foundation

Department

Mathematics and Statistics

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