proposition: Lemma natrG_gt0 G : #|G|%:R > 0 :> R.
proof: Proof. by rewrite ltr0n cardG_gt0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)