proposition: Lemma root_roots p a b x : x \in roots p a b -> root p x.
proof: Proof. by case: rootsP=> // p0 <- _ /andP []. 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)