proposition: Lemma invertible_colimit_to_cocone : forall a b c, is_colimit a -> is_colimit b -> cosocle a = cosocle b -> cocone_target a = c -> invertible c (colimit_to_cocone a b).
proof: Proof. ir. uhg. sh (colimit_to_cocone b a). app are_inverse_colimit_to_cocone. Qed.
imports: Arith limits