proposition: Lemma pow_le : forall (a:R) (n:nat), 0 <= a -> 0 <= a ^ n.
proof: Proof. intros; induction n as [| n Hrecn]. - simpl; left; apply Rlt_0_1. - simpl; apply Rmult_le_pos; assumption. Qed.
imports: ArithRing Rdefinitions Raxioms RIneq Rpow_def R_Ifp Rbasic_fun R_sqr SplitAbsolu SplitRmult ArithProp Zpower Ztac