proposition: Lemma realN : {mono (@GRing.opp R) : x / x \is real}.
proof: Proof. exact: rpredN. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)