Translation-like Actions and Aperiodic Subshifts on Groups
Abstract
It is well known that if $G$ admits a f.g. subgroup $H$ with a weakly
aperiodic SFT (resp. an undecidable domino problem), then $G$
itself has a weakly aperiodic SFT (resp. an undecidable domino problem).
We prove that we can replace the property "$H$ is a subgroup of $G$"
by "$H$ acts translation-like on $G$", provided $H$ is finitely presented.
In particular:
* If $G_1$ and $G_2$ are f.g. infinite groups, then $G_1
\times G_2$ has a weakly aperiodic SFT (and actually a
undecidable domino problem). In particular the Grigorchuk group
has an undecidable domino problem.
* Every infinite f.g. $p$-group admits a weakly
aperiodic SFT.
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