proposition: Lemma eq_map2_mx (f g : R -> S -> T) : f =2 g -> @map2_mx _ _ _ f m n =2 @map2_mx _ _ _ g m n.
proof: Proof. by move=> eq_fg M M'; apply/eq_in_map2_mx. 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)