The Δ0α-Computable Enumerations of the Classes of Projective Planes

详细

Studying computable representations of projective planes, for the classes K of pappian, desarguesian, and all projective planes, we prove that K^c/≃ admits no hyperarithmetical Friedberg enumeration and admits a Friedberg Δ⁰_α+3-computable enumeration up to a Δ⁰_α-computable isomorphism.