proposition: Lemma fdist_prod_of_rVE a : fdist_prod_of_rV a = P (row_mx (\row_(i < 1) a.1) a.2).
proof: Proof. case: a => x y; rewrite /fdist_prod_of_rV fdistmapE /=. rewrite (_ : (x, y) = f (row_mx (\row_(i < 1) x) y)); last first. by rewrite /f row_mx_row_ord0 rbehead_row_mx. by rewrite (big_pred1_inj inj_f). Qed.
imports: mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR logb realType_ext ssr_ext ssralg_ext bigop_ext