Substitutions with Cofinal Fixed Points
Bo TAN, Zhi-Xiong WEN, Jun WU, Zhi-Ying WEN (2006)
Annales de l’institut Fourier
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Let be a substitution over a 2-letter alphabet, say . If and begin with and respectively, has two fixed points beginning with and respectively. We characterize substitutions with two cofinal fixed points (i.e., which differ only by prefixes). The proof is a combinatorial one, based on the study of repetitions of words in the fixed points.