(* Instance Iso_atoms_sub_mor : Morphisms.Proper (eq ==> AtomSetImpl.Subset ==> eq ==> eq ==> impl) Iso.  Instance DefEq_atoms_sub_mor : Morphisms.Proper (eq ==> AtomSetImpl.Subset ==> eq ==> eq ==> eq ==> impl) DefEq. *)

(* Specifications: *)
Lemma DefEq_weaken_available :
forall G D A B T, DefEq G D A B T -> DefEq G (dom G) A B T.
Lemma Iso_weaken_available :
forall G D A B, Iso G D A B -> Iso G (dom G) A B.