proposition: Lemma prev_root0 a b : prev_root 0 a b = b.
proof: Proof. by rewrite /prev_root eqxx. 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)