Topological Properties of Omega Context Free Languages

  title={Topological Properties of Omega Context Free Languages},
  author={Avram Gold and Miika Linna and Maurice Nivat},
This paper is a study of topological properties of omega context free languages (ω-CFL). We first extend some decidability results for the deterministic ones (ωDCFL), proving that one can decide whether an ω-DCFL is in a given Borel class, or in the Wadge class of a given ω-regular language . We prove that ω-CFL exhaust the hierarchy of Borel sets of finite rank, and that one cannot decide the borel class of an ω-CFL, giving an answer to a question of [LT94]. We give also a (partial) answer to… CONTINUE READING