fact: Definition function f := ∀ ∀ ∀ opair $2 $1 ∈ shift 3 f → opair $2 $0 ∈ shift 3 f → $1 ≡ $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)