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Conjugates of characteristic Sturmian words generated by morphisms

Combinatorics 2010-03-16 v1 Discrete Mathematics

Abstract

This article is concerned with characteristic Sturmian words of slope α\alpha and 1α1-\alpha (denoted by cαc_\alpha and c1αc_{1-\alpha} respectively), where α(0,1)\alpha \in (0,1) is an irrational number such that α=[0;1+d1,d2,...,dnˉ]\alpha = [0;1+d_1,\bar{d_2,...,d_n}] with dnd11d_n \geq d_1 \geq 1. It is known that both cαc_\alpha and c1αc_{1-\alpha} are fixed points of non-trivial (standard) morphisms σ\sigma and σ^\hat{\sigma}, respectively, if and only if α\alpha has a continued fraction expansion as above. Accordingly, such words cαc_\alpha and c1αc_{1-\alpha} are generated by the respective morphisms σ\sigma and σ^\hat{\sigma}. For the particular case when α=[0;2,rˉ]\alpha = [0;2,\bar{r}] (r1r\geq1), we give a decomposition of each conjugate of cαc_\alpha (and hence c1αc_{1-\alpha}) into generalized adjoining singular words, by considering conjugates of powers of the standard morphism σ\sigma by which it is generated. This extends a recent result of Lev\'{e} and S\ee bold on conjugates of the infinite Fibonacci word.

Keywords

Cite

@article{arxiv.0708.4387,
  title  = {Conjugates of characteristic Sturmian words generated by morphisms},
  author = {Amy Glen},
  journal= {arXiv preprint arXiv:0708.4387},
  year   = {2010}
}

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11 pages