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Transitive action on finite points of a full shift and a finitary Ryan’s theorem




TekijätSalo, Ville

KustantajaCambridge University Press

Julkaisuvuosi2019

JournalErgodic Theory and Dynamical Systems

Tietokannassa oleva lehden nimiErgodic Theory and Dynamical Systems

Vuosikerta39

Numero6

Aloitussivu1637

Lopetussivu1667

Sivujen määrä31

ISSN1469-4417

eISSN1469-4417

DOIhttps://doi.org/10.1017/etds.2017.84


Tiivistelmä

We show that on the four-symbol full shift, there is a finitely generated subgroup of the automorphism group whose action is (set-theoretically) transitive of all orders on the points of finite support, up to the necessary caveats due to shift-commutation. As a corollary, we obtain that there is a finite set of automorphisms whose centralizer is Z (the shift group), giving a finitary version of Ryan's theorem (on the four-symbol full shift), suggesting an automorphism group invariant for mixing subshifts of finite type (SFTs). We show that any such set of automorphisms must generate an infinite group, and also show that there is also a group with this transitivity property that is a subgroup of the commutator subgroup and whose elements can be written as compositions of involutions. We ask many related questions and prove some easy transitivity results for the group of reversible Turing machines, topological full groups and Thompson's V.



Last updated on 2024-26-11 at 13:00