proposition: Lemma rmorphXz (R' : unitRingType) (f : {rmorphism R -> R'}) n : {in GRing.unit, {morph f : x / x ^ n}}.
proof: Proof. by case: n => n x Ux; rewrite ?rmorphV ?rpredX ?rmorphXn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)