We state the following results: the family of all infinite computably enumerable sets has no computable numbering; the family of all infinite Π11 sets has no Π11 -computable numbering; the family of all infinite Σ21 sets has no Σ21 -computable numbering. For k > 2, the existence of a Σk1 -computable numbering for the family of all infinite Σk1 sets leads to the inconsistency of ZF.
- analytical hierarchy
- computable numberings
- Friedberg numbering
- Gödel’s axiom of constructibility
- Godel's axiom of constructibility