fact: Definition function' f A := pairing f A ∧ ∀ ∃ $0 ∈ shift 2 A ∧ opair $0 $1 ∈ shift 2 f ∧ ∀ opair $1 $0 ∈ shift 2f → $2 ≡ $0.
imports: Undecidability.FOL.ZF Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Sets.ZF Lia Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation)