Environment v4.30.0. The archive's epoch is v4.33.0; only submissions in v4.30.0 can cite this work.

Proof of `Fagin’s theorem` (1st statement)

groundedproofs/Lax678846Proofs/NPDefinable.lean · lax-678846

What this proof establishes

no assumptions

thm✓Lax678846.Fagin (1st statement)

Assuming the claims on the left, the claim on the right holds — checked by the archive's pipeline. Proof code is not displayed here.

Read the Lean proof on GitHub

Description

Combine the concrete nondeterministic certificate verifier with the existential second-order definition constructed for each NP property.