Admissible Reversing and Extended Symmetries for Bijective Substitutions

Abstract

In this paper, we deal with reversing and extended symmetries of subshifts generated by bijective substitutions. We survey some general algebraic and dynamical properties of these subshifts and recall known results regarding their symmetry groups. We provide equivalent conditions for a permutation on the alphabet to generate a reversing/extended symmetry, and algorithms how to compute them. Moreover, for any finite group H and any subgroup P of the d-dimensional hyperoctahedral group, we construct a bijective substitution which generates an aperiodic subshift with symmetry group Zd×H and extended symmetry group (Zd⋊P)×H. A similar construction with the same symmetry group, but with extended symmetry group (Zd×H)⋊P is also provided under a mild assumption on the dimension.