unfold comp_map_map in |- *; simpl in |- *.
unfold Map_eq in |- *; simpl in |- *; auto with algebra.
Qed.
Hint Resolve Id_unit_l: algebra.

(* Specifications: *)
Lemma Id_is_bijective : forall A : Setoid, bijective (Id A).
intros A; red in |- *.