English

Shifts on the lamplighter group

Dynamical Systems 2024-02-23 v1 Logic in Computer Science Group Theory

Abstract

We prove that the lamplighter group admits strongly aperiodic SFTs, has undecidable tiling problem, and the entropies of its SFTs are exactly the upper semicomputable nonnegative real numbers, and some other results. These results follow from two relatively general simulation theorems, which show that for a large class of effective subshifts on the sea-level subgroup, their induction to the lamplighter group is sofic; and the pullback of every effective Cantor system on the integers admits an SFT cover. We exhibit a concrete strongly aperiodic set with 14881488 tetrahedra. We show that metabelian Baumslag-Solitar groups are intersimulable with lamplighter groups, and thus we obtain the same characterization for their entropies.

Keywords

Cite

@article{arxiv.2402.14508,
  title  = {Shifts on the lamplighter group},
  author = {Laurent Bartholdi and Ville Salo},
  journal= {arXiv preprint arXiv:2402.14508},
  year   = {2024}
}
R2 v1 2026-06-28T14:57:02.277Z