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Glider automata on all transitive sofic shifts

Published online by Cambridge University Press:  30 September 2021

JOHAN KOPRA*
Affiliation:
Department of Mathematics and Statistics, University of Turku, FI-20014 Turku, Finland
*
(e-mail: jtjkop@utu.fi)

Abstract

For any infinite transitive sofic shift X we construct a reversible cellular automaton (that is, an automorphism of the shift X) which breaks any given finite point of the subshift into a finite collection of gliders traveling into opposing directions. This shows in addition that every infinite transitive sofic shift has a reversible cellular automaton which is sensitive with respect to all directions. As another application we prove a finitary version of Ryan’s theorem: the automorphism group $\operatorname {\mathrm {Aut}}(X)$ contains a two-element subset whose centralizer consists only of shift maps. We also show that in the class of S-gap shifts these results do not extend beyond the sofic case.

MSC classification

Type
Original Article
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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