proposition: Lemma pred_ext_2 : forall (P Q : forall (x1:A1) (x2:A2 x1), Prop), (forall x1 x2, P x1 x2 <-> Q x1 x2) -> P = Q.
proof: Proof. Proof using. repeat (intros; apply fun_ext_dep). intros. apply~ prop_ext. Qed.
imports: TLC(LibTactics LibAxioms)