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Substitutive systems and a finitary version of Cobham's theorem (1908.11244v2)
Published 29 Aug 2019 in math.CO, cs.FL, math.DS, and math.NT
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.