proposition: Lemma flip_nonpos_minus (x y : R) : y - x ≤ 0 <-> y ≤ x.
proof: Proof. pattern x at 2;apply (transport _ (plus_0_l x)). apply flip_le_minus_l. Qed.
imports: HoTT.Classes.interfaces.abstract_algebra HoTT.Classes.interfaces.orders HoTT.Classes.theory.groups HoTT.Classes.theory.rings HoTT.Classes.orders.semirings