  Automorphism groups are intrincate conjugacy invariants for subshifts, which
can reveal important features of the dynamical structure of a shift action. One
important case is the study of automorphism groups when the underlying subshift
has a very rigid structure, e.g. substitutive subshifts or aperiodic
constructions with large-scale self-similarity, such as the Robinson shift.
  In this work we study the automorphism group of bijective substitutive
subshifts, and a potential generalization in the form of the group of extended
symmetries, studied previously by Michael Baake, John Roberts and Reem Yassawi
(arXiv:1611.05756); these symmetries, by allowing for shearing and other
deformations of the underlying group, may reveal additional information of a
geometric nature about the structure of these subshifts.
