proposition: Lemma map2_xrow i1 i2 : map2_mx (xrow i1 i2 A) (xrow i1 i2 B) = xrow i1 i2 (map2_mx A B).
proof: Proof. by apply/matrixP=> i j; rewrite !mxE. 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)