proposition: Lemma mxtraceD A B : \tr (A + B) = \tr A + \tr B.
proof: Proof. exact: raddfD. 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)