proposition: Theorem le_trans : forall a b c, a <= b -> b <= c -> a <= c.
proof: Proof. destruct 1. subst b;auto. destruct 1. subst b;right;auto. right;eapply lt_trans;eauto. Qed.
imports: Arith Omega Compare_dec Relations Wellfounded Tools More_nat Wf_nat AccP not_decreasing ArithRing term rpo List