proposition: Lemma real_ler_normlP x y : x \is real -> reflect ((-x <= y) * (x <= y)) (`|x| <= y).
proof: Proof. by move=> Rx; rewrite real_ler_norml // lerNl; apply: (iffP andP) => [] []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)