proposition: Lemma Cnat_sum_eq1 (I : finType) (P : pred I) (F : I -> algC) : (forall i, P i -> F i \in Cnat) -> \sum_(i | P i) F i = 1 -> {i : I | [/\ P i, F i = 1 & forall j, j != i -> P j -> F j = 0]}.
proof: Proof. exact: natr_sum_eq1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun ssrnat eqtype seq choice) mathcomp(div fintype path bigop finset prime order ssralg) mathcomp(poly polydiv mxpoly generic_quotient countalg) mathcomp(ssrnum closed_field ssrint archimedean rat intdiv) mathcomp(algebraics_fundamentals)