Proof of `Fagin’s theorem` (1st statement)
groundedproofs/Lax678846Proofs/NPDefinable.lean · lax-678846
What this proof establishes
no assumptions
Assuming the claims on the left, the claim on the right holds — checked by the archive's pipeline. Proof code is not displayed here.
Description
Combine the concrete nondeterministic certificate verifier with the existential second-order definition constructed for each NP property.