English

The separation problem for regular languages by piecewise testable languages

Formal Languages and Automata Theory 2013-03-12 v1

Abstract

Separation is a classical problem in mathematics and computer science. It asks whether, given two sets belonging to some class, it is possible to separate them by another set of a smaller class. We present and discuss the separation problem for regular languages. We then give a direct polynomial time algorithm to check whether two given regular languages are separable by a piecewise testable language, that is, whether a BΣ1(<)B{\Sigma}1(<) sentence can witness that the languages are indeed disjoint. The proof is a reformulation and a refinement of an algebraic argument already given by Almeida and the second author.

Keywords

Cite

@article{arxiv.1303.2143,
  title  = {The separation problem for regular languages by piecewise testable languages},
  author = {Lorijn van Rooijen and Marc Zeitoun},
  journal= {arXiv preprint arXiv:1303.2143},
  year   = {2013}
}
R2 v1 2026-06-21T23:39:09.555Z