proposition: Lemma minus_le : forall a b, leq lt a b -> a - b = zero.
proof: Proof. intros a b ; rewrite le_lt_eq; destruct 1 as [Hlt | Heq]. - apply minus_lt; auto. - subst b; apply minus_a_a. Qed.
imports: Coq(Arith Max Bool Lia Compare_dec Relations Ensembles Wellfounded Bool RelationClasses Operators_Properties ArithRing Logic.Eqdep_dec) hydras(More_Arith Restriction DecPreOrder) hydras(OrdNotations)