proposition: Lemma forallSimp (T : System) (f : Formula) (v : nat): SysPrf T (allH v, f)%fol -> SysPrf T f.
proof: Proof. intros H; rewrite <- subFormulaId with L f v; now apply forallE. Qed.
imports: Coq(Ensembles List) hydras.Ackermann(ListExt folProof folProp Deduction)