proposition: Lemma successfull_inv : forall k p, successfull (iter_step k p) = true -> forall l, l < k -> iter_step l p <> None.
proof: Proof. intros. intro. ded (unsuccessfull_preserved H1 H0). rewrite H2 in H. discr. Qed.
imports: Coq(Relations Wellfounded) CoLoR(ASubstitution ATerm EqUtil ListUtil LogicUtil VecUtil AVariables BoolUtil NatUtil SN AVariables Lexico)