proposition: Lemma mulmx_block m1 m2 n1 n2 p1 p2 (Aul : 'M_(m1, n1)) (Aur : 'M_(m1, n2)) (Adl : 'M_(m2, n1)) (Adr : 'M_(m2, n2)) (Bul : 'M_(n1, p1)) (Bur : 'M_(n1, p2)) (Bdl : 'M_(n2, p1)) (Bdr : 'M_(n2, p2)) : block_mx Aul Aur Adl Adr *m block_mx Bul Bur Bdl Bdr = block_mx (Aul *m Bul + Aur *m Bdl) (Aul *m Bur + Aur *m Bdr) (Adl *m Bul + Adr *m Bdl) (Adl *m Bur + Adr *m Bdr).
proof: Proof. by rewrite mul_col_mx !mul_row_block. 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 countalg finalg zmodp)