On Existentially First-order Deenable Languages and Their Relation to Np

@inproceedings{Borchert1998OnEF,
  title={On Existentially First-order Deenable Languages and Their Relation to Np},
  author={Bernd Borchert and Dietrich Kuske},
  year={1998}
}
Under the assumption that the Polynomial-Time Hierarchy does not collapse we show for a regular language L: The unbalanced polynomialtime leaf language class determined by L equals NP i L is existentially but not quanti erfree de nable in FO[<;min;max;+1; 1]. Furthermore, no such class lies properly between NP and co-1-NP or NP co-NP. The proofs rely on a… CONTINUE READING