proposition: Lemma const_mx_is_semi_additive : semi_additive const_mx.
proof: Proof. by split=> [|a b]; 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)