proposition: Lemma domb_fold : (domb r d) -> (forall a, d a -> d' a) -> r ⨾ ⦗d'⦘ ≡ r.
proof: Proof. unfold eqv_rel, seq; split; red; ins; desf; eauto 6. Qed.
imports: HahnBase HahnSets HahnRelationsBasic HahnEquational HahnRewrite Setoid