proposition: Lemma genmx_sums P n (B_ : I -> 'M_n) : <<(\sum_(i | P i) B_ i)%MS>>%MS = (\sum_(i | P i) <<B_ i>>)%MS.
proof: Proof. exact: (big_morph _ (@genmx_adds n n n) (@genmx0 n n)). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg finalg zmodp matrix)