definition bp': concrete_space → basic_pair ≝ λc.bp c.
coercion bp'.
+lemma setoid_OF_OA : OA → setoid.
+intros; apply (oa_P o);
+qed.
+
+coercion setoid_OF_OA.
+
+definition binary_downarrow :
+ ∀C:concrete_space.binary_morphism1 (form C) (form C) (form C).
+intros; constructor 1;
+[ intros; apply (↓ c ∧ ↓ c1);
+| intros; apply ((†H)‡(†H1));]
+qed.
+
record convergent_relation_pair (CS1,CS2: concrete_space) : Type ≝
{ rp:> arrows1 ? CS1 CS2;
respects_converges:
- ∀b,c.
+ ∀b,c. (rp\sub\c)⎻ (Ext⎽CS2 (b ↓ c)) = ?(*
extS ?? rp \sub\c (BPextS CS2 (b ↓ c)) =
BPextS CS1 ((extS ?? rp \sub\f b) ↓ (extS ?? rp \sub\f c));
respects_all_covered:
- extS ?? rp\sub\c (BPextS CS2 (form CS2)) = BPextS CS1 (form CS1)
+ extS ?? rp\sub\c (BPextS CS2 (form CS2)) = BPextS CS1 (form CS1)*)
}.
definition rp' : ∀CS1,CS2. convergent_relation_pair CS1 CS2 → relation_pair CS1 CS2 ≝