proposition: Lemma map2_block_mx : map2_mx (block_mx Aul Aur Adl Adr) (block_mx A'ul A'ur A'dl A'dr) = block_mx (map2_mx Aul A'ul) (map2_mx Aur A'ur) (map2_mx Adl A'dl) (map2_mx Adr A'dr).
proof: Proof. by apply/matrixP=> i j; do 3![rewrite !mxE //; case: split => ?]. 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)