proposition: Lemma fdist_nthE a : fdist_nth a = \sum_(x : 'rV[A]_n | x ``_ i == a) P x.
proof: Proof. by rewrite fdistmapE. 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