(** Respectful morphisms. *)
  
  (** The fully dependent version, not used yet. *)
  
  Definition respectful_hetero
  (A B : Type)
  (C : A -> Type) (D : B -> Type)
  (R : A -> B -> Prop)
  (R' : forall (x : A) (y : B), C x -> D y -> Prop) :
    (forall x : A, C x) -> (forall x : B, D x) -> Prop :=
    fun f g => forall x y, R x y -> R' x y (f x) (g y).(** The non-dependent version is an instance where we forget dependencies. *)
  
  Definition respectful (R : relation A) (R' : relation B) : relation (A -> B) :=
    Eval compute in @respectful_hetero A A (fun _ => B) (fun _ => B) R (fun _ _ => R').(** Non-dependent pointwise lifting *)
Definition pointwise_relation A {B} (R : relation B) : relation (A -> B) :=
  fun f g => forall a, R (f a) (g a).

Lemma rewrite_relation_eq_dom {A B R} `{RewriteRelation B R}: RewriteRelation (respectful (@Logic.eq A) R).