English

It is undecidable if two regular tree languages can be separated by a deterministic tree-walking automaton

Logic in Computer Science 2017-03-21 v2 Formal Languages and Automata Theory

Abstract

The following problem is shown undecidable: given regular languages L,K of finite trees, decide if there exists a deterministic tree-walking automaton which accepts all trees in L and rejects all trees in K. The proof uses a technique of Kopczy\'nski from LICS 2016.

Keywords

Cite

@article{arxiv.1703.04997,
  title  = {It is undecidable if two regular tree languages can be separated by a deterministic tree-walking automaton},
  author = {Mikołaj Bojańczyk},
  journal= {arXiv preprint arXiv:1703.04997},
  year   = {2017}
}
R2 v1 2026-06-22T18:45:55.811Z