proposition: Lemma inv2 : forall A B (f : CSetoid_fun A B) (H : bijective f) (a : A), invfun f H (f a) [=] a.
proof: Proof. intros. unfold invfun in |- *; case inv; simpl. destruct H as [H0 H1]. intros x. now apply injective_imp_injective_weak. Qed.
imports: CoRN.algebra.CSetoids