proposition: Lemma derplW x : x \in `[a, b] -> p.[x] <= p.[b].
proof: Proof. by move=> axb; rewrite ler_horner ?(itvP axb). 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)