proposition: Lemma lead_coef_poly_XaY p : lead_coef (poly_XaY p) = (lead_coef p)%:P.
proof: Proof. rewrite lead_coef_comp ?size_XaddC // -['Y]opprK -polyCN lead_coefXsubC. by rewrite expr1n mulr1 lead_coef_map_inj //; apply: polyC_inj. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype choice ssrnat seq) mathcomp(fintype tuple finfun bigop fingroup perm div) mathcomp(ssralg zmodp matrix mxalgebra) mathcomp(poly polydiv mxpoly binomial)