proposition: Lemma expf_eq0 x n : (x ^+ n == 0) = (n > 0) && (x == 0).
proof: Proof. elim: n => [|n IHn]; first by rewrite oner_eq0. by rewrite exprS mulf_eq0 IHn andKb. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)