proposition: Lemma roots_onP p i s : roots_on p i s -> {in i, root p =1 mem s}.
proof: Proof. by move=> hp x hx; move: (hp x); rewrite hx. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg poly polydiv ssrnum zmodp) mathcomp(polyorder path interval ssrint)