proposition: Lemma exists_n_switch n phi : ∃i exists_n n phi = exists_n n (∃i phi).
proof: Proof. induction n. easy. cbn. now rewrite IHn. Qed.
imports: PeanoNat Lia Vector List Undecidability.SOL(SOL PA2) Undecidability.Shared.Libs.PSL(Vectors) Undecidability.SOL.Util(Syntax Subst Tarski PA2_facts PA2_categoricity) Undecidability.Synthetic(Definitions DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts ReducibilityFacts) Undecidability.H10(H10p) Undecidability.Shared.Dec