proposition: Lemma co_hprXYE la mu (p q : pol) : co_hpXY la mu (p(X) * q(Y)) = (co_hp la p) * (co_hp mu q).
proof: Proof. by rewrite /co_hpXY; unlock; rewrite /= co_hpYE linearZ mulrC. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(ssrint rat ssralg ssrnum algC matrix vector) mathcomp(mpoly) tools partition ordtype antisym Schur_mpoly Schur_altdef sympoly homogsym permcent