proposition: Lemma soundness_class' {ff : falsity_flag} phi : [] ⊢C phi -> valid phi.
proof: Proof. Proof using LEM. intros H % soundness_class. clear LEM. intros D I rho; now apply H. Qed.
imports: Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Deduction.FullND Undecidability(Shared.ListAutomation) Vector Lia