✐‹creator "Kevin Kappelmann"› subsection ‹Order› theory Binary_Relations_Order_Base imports Binary_Relation_Functions HOL.Orderings begin lemma le_relI [intro]: assumes "⋀x y. R x y ⟹ S x y" shows "R ≤ S" using assms by (rule predicate2I) lemma le_relD [dest]: assumes "R ≤ S" and "R x y" shows "S x y" using assms by (rule predicate2D) lemma le_relE: assumes "R ≤ S" and "R x y" obtains "S x y" using assms by blast end