Proof with auto.
pattern l, (qs l).
apply (qs_det_parts.rect counted_cmp SimplyProfiled_ext)...
intros.
unfold qs_det_parts.partitionPart.
rewrite bind_cost.
rewrite partition_cost.
unfold qs_det_parts.lowRecPart.
repeat rewrite bind_cost.
rewrite return_cost.
rewrite <- plus_assoc.
f_equal.
do 2 rewrite partition_result.
rewrite plus_0_r.
unfold qs.
do 3 f_equal; apply filter_eq_morphism...
intro...
rewrite Ecmp_sym.
unfold Egtb.
destruct (Ecmp X h a)...
intro...
unfold Eltb.
rewrite Ecmp_sym.
destruct (Ecmp X h a)...
Qed.
(* Since cost_qs tells us all we need to know about qs (for the purposes of proving its average case complexity), we will not need any further monad reasoning. We will need some R stuff: *)
Coercion INR: nat >-> R.
Hint Resolve Rmult_lt_0_compat Rmult_lt_0_compat Rinv_0_lt_compat Rle_Rinv: real.
(* We now define the recurrence relation *)
Inductive CR: nat -> R -> Prop :=
| C0: CR 0 0
| Cn n (l: list R): elemsR CR (nats 0 (S n)) l -> CR (S n) (n + 2 * Ravg l).
Hint Constructors CR.
(* .. and note that it is a function: *)

Lemma CRuniq: forall n r, CR n r -> forall r', CR n r' -> r = r'.
Proof with auto.