proposition: Lemma g_correct : forall i, f (g i) = a.
proof: Proof. intro i. destruct i; simpl. destruct (ch_min (H 0)). simpl. intuition. destruct (ch_min (H (S (g i)))). simpl. intuition. Qed.
imports: CoLoR(RelUtil NatUtil Path LeastNat LogicUtil ClassicUtil SN NotSN_IS SortUtil ListUtil) Coq(IndefiniteDescription)