English

Context-free ordinals

Formal Languages and Automata Theory 2015-03-19 v1

Abstract

We consider context-free languages equipped with the lexicographic ordering. We show that when the lexicographic ordering of a context-free language is scattered, then its Hausdorff rank is less than ωω\omega^\omega. As a corollary of this result we obtain that an ordinal is the order type of a well-ordered context-free language iff it is less than ωωω\omega^{\omega^\omega}.

Cite

@article{arxiv.1103.5421,
  title  = {Context-free ordinals},
  author = {Zoltan Esik and Szabolcs Ivan},
  journal= {arXiv preprint arXiv:1103.5421},
  year   = {2015}
}
R2 v1 2026-06-21T17:45:45.655Z