fact: CoInductive unsplit_spec m n (i : 'I_(m + n)) : 'I_m + 'I_n -> bool -> Type := | UnsplitLo (j : 'I_m) of i = lshift _ j : unsplit_spec i (inl _ j) true | UnsplitHi (k : 'I_n) of i = rshift _ k : unsplit_spec i (inr _ k) false.
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)