proposition: Lemma unsplit_prodK n m : cancel (@unsplit_prod n m) (@split_prod n m).
proof: Proof. move: m => [[? [[]]]//|m [i j]]; congr (_, _); apply/val_inj => /=. - by rewrite divnMDl// divn_small// addn0. - by rewrite modnMDl modn_small. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(mathcomp_extra boolp classical_sets Rstruct) mathcomp(ssrnum ereal) mathcomp(lra Rstruct reals) Reals ssrR Reals_ext Ranalysis_ext ssr_ext ssralg_ext logb realType_ext fdist