Fixpoint AbsList (l:list R) (x:R) : list R :=
  match l with
    | nil => nil
    | a :: l' => (Rabs (a - x) / 2) :: (AbsList l' x)
  end.

Lemma MinRlist_P2 : forall l:list R, (forall y:R, In y l -> 0 < y) -> 0 < MinRlist l.