proposition: Lemma shift_less_minus : forall x y z : R, x[+]z [<] y -> x [<] y[-]z.
proof: Proof. intros. rstepl (x[+]z[-]z). apply minus_resp_less. assumption. Qed.
imports: CoRN.tactics.FieldReflection CoRN.tactics.Rational CoRN.algebra.CSetoids Coq(Lia)