proposition: Lemma mulcmC : commutative mulcm.
proof: Proof. by move=> m1 m2; apply/eqP/cmP=> i; rewrite !mulcmE addnC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap