proposition: Lemma alpha_gt0 : alpha > 0.
proof: Proof. by rewrite sqrtr_gt0 mulr_gt0 ?invr_gt0 ?sqrtr_gt0 ?ltr0n. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_fingroup all_algebra) mathcomp(all_solvable all_field polyrcf) Abel(various classic_ext map_gal algR) Abel(char0 cyclotomic_ext real_closed_ext)