Abstract
We study substitutive systems generated by nonprimitive substitutions and show that transitive subsystems of substitutive systems are substitutive. As an application we obtain a complete characterisation of the sets of words that can appear as common factors of two automatic sequences defined over multiplicatively independent bases. This generalises the famous theorem of Cobham.
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Byszewski, J., Konieczny, J. & Krawczyk, E. Substitutive Systems and a Finitary Version of Cobham’s Theorem. Combinatorica 41, 765–801 (2021). https://doi.org/10.1007/s00493-020-4311-x
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DOI: https://doi.org/10.1007/s00493-020-4311-x