proposition: Lemma join_ub_3_l x y z : x ≤ x ⊔ y ⊔ z.
proof: Proof. transitivity (x ⊔ y); apply join_ub_l. Qed.
imports: HoTT.Classes.interfaces.abstract_algebra HoTT.Classes.interfaces.orders HoTT.Classes.orders.semirings HoTT.Classes.theory.lattices