Thue-Morse sequence and groups of intermediate growth

Abstract

We consider the substitution subshift generated by the Thue-Morse substitution $0\to 01$, $1\to 10$. We prove that the topological full group of the subshift contains a subgroup of intermediate growth. Namely, one group from the family known as the Grigorchuk groups embeds into this group. To obtain our main result, we prove an embedding theorem for topological full groups, and also develop a technique to prove isomorphism of groups using the Schreier graphs.

40 pages, 5 figures