English

Nondeterministic tree-walking automata are not closed under complementation

Formal Languages and Automata Theory 2024-12-04 v1

Abstract

It is proved that the family of tree languages recognized by nondeterministic tree-walking automata is not closed under complementation, solving a problem raised by Boja\'nczyk and Colcombet ("Tree-walking automata do not recognize all regular languages", SIAM J. Comp. 38 (2008) 658--701). In addition, it is shown that nondeterministic tree-walking automata are stronger than unambiguous tree-walking automata.

Keywords

Cite

@article{arxiv.2412.02618,
  title  = {Nondeterministic tree-walking automata are not closed under complementation},
  author = {Olga Martynova and Alexander Okhotin},
  journal= {arXiv preprint arXiv:2412.02618},
  year   = {2024}
}

Comments

39 pages, 22 figures

R2 v1 2026-06-28T20:21:39.783Z