proposition: Lemma proof_irrelevance : forall (P : Prop) (p q : P), p = q.
proof: Proof. Proof using. intros P p q. set (f := fun b => match b with | trueP => p | falseP => q end). change p with (f trueP). change q with (f falseP). rewrite~ trueP_eq_falseP. Qed.
imports: TLC(LibTactics LibAxioms)