(* Refl of '->' '/\': basic properties *)

Fixpoint make_impl (A : Type) (eval : A -> Prop) (l : list A) (goal : Prop) {struct l} : Prop :=
  match l with
    | nil => goal
    | cons e l => (eval e) -> (make_impl eval l goal)
  end.

Theorem make_impl_map : forall (A B: Type) (eval : A -> Prop) (eval' : A*B -> Prop) (l : list (A*B)) r (EVAL : forall x, eval' x <-> eval (fst x)), make_impl eval' l r <-> make_impl eval (List.map fst l) r.