A notion of effectiveness for subshifts on finitely generated groups

Abstract

We generalize the classical definition of effectively closed subshift to finitely generated groups. We study classical stability properties of this class and then extend this notion by allowing the usage of an oracle to the word problem of a group. This new class of subshifts forms a conjugacy class that contains all sofic subshifts. Motivated by the question of whether there exists a group where the class of sofic subshifts coincides with that of effective subshifts, we show that the inclusion is strict for several groups, including recursively presented groups with undecidable word problem, amenable groups and groups with more than two ends. We also provide an extended model of Turing machine which uses the group itself as a tape and characterizes our extended notion of effectiveness. As applications of these machines we prove that the origin constrained domino problem is undecidable for any group of the form $G\times \mathbb{Z}$ subject to a technical condition on $G$ and we present a simulation theorem which is valid in any finitely generated group.

References in corpus (1)

• Simulation of Effective Subshifts by Two-dimensional Subshifts of Finite Type

Cited by in corpus (9)

• The group of reversible Turing machines
• A generalization of the simulation theorem for semidirect products
• Periodic Points on Shifts of Finite Type and Commensurability Invariants of Groups
• On the entropies of subshifts of finite type on countable amenable groups
• Aperiodic Subshifts of Finite Type on Groups
• Invariant sets and nilpotency of endomorphisms of algebraic sofic shifts
• Self-simulable groups
• A geometric simulation theorem on direct products of finitely generated groups
• Soficity of free extensions of effective subshifts