Fixpoint datDepth (A : Set)(t : DistApproxTree A) : nat :=
  match t with
    | dat_leaf o => O
    | dat_internal t1 t2 =>
      S (max (datDepth t1) (datDepth t2))
  end.

Lemma rel_map_Rnd_NoDup : forall n ls, rel_map (evalDet (Rnd n)) (getAllBlists n) ls -> NoDup ls.