proposition: Lemma Cauchy_homsymm_homsymh : Cauchy_kernel d = \sum_(la : 'P_d) 'hm[la](X) * 'hh[la](Y).
proof: Proof. rewrite Cauchy_symm_symh. by apply eq_bigr => i _; rewrite polyXY_scale symmX. 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