English

Morphic words and equidistributed sequences

Dynamical Systems 2019-11-25 v3 Formal Languages and Automata Theory

Abstract

The problem we consider is the following: Given an infinite word ww on an ordered alphabet, construct the sequence νw=(ν[n])n\nu_w=(\nu[n])_n, equidistributed on [0,1][0,1] and such that ν[m]<ν[n]\nu[m]<\nu[n] if and only if σm(w)<σn(w)\sigma^m(w)<\sigma^n(w), where σ\sigma is the shift operation, erasing the first symbol of ww. The sequence νw\nu_w exists and is unique for every word with well-defined positive uniform frequencies of every factor, or, in dynamical terms, for every element of a uniquely ergodic subshift. In this paper we describe the construction of νw\nu_w for the case when the subshift of ww is generated by a morphism of a special kind; then we overcome some technical difficulties to extend the result to all binary morphisms. The sequence νw\nu_w in this case is also constructed with a morphism. At last, we introduce a software tool which, given a binary morphism φ\varphi, computes the morphism on extended intervals and first elements of the equidistributed sequences associated with fixed points of φ\varphi.

Keywords

Cite

@article{arxiv.1807.08321,
  title  = {Morphic words and equidistributed sequences},
  author = {Mélodie Andrieu and Anna E. Frid},
  journal= {arXiv preprint arXiv:1807.08321},
  year   = {2019}
}