proposition: Lemma unsplitP m n (i : 'I_(m + n)) : unsplit_spec i (split i) (i < m)%N.
proof: Proof. by case: splitP=> j eq_j; constructor; apply/val_inj. 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)