proposition: Theorem le_tail : forall a n b b', b <= b' -> cons a n b <= cons a n b'.
proof: Proof. destruct 1. subst b; left; auto. right; auto with T1. Qed.
imports: Arith Omega Compare_dec Relations Wellfounded Tools More_nat Wf_nat AccP not_decreasing ArithRing term rpo List