proposition: Lemma map2_col_mx : map2_mx (col_mx Aul Adl) (col_mx A'ul A'dl) = col_mx (map2_mx Aul A'ul) (map2_mx Adl A'dl).
proof: Proof. by apply/matrixP=> i j; do 2![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)