Definition horner_morph u of commr_rmorph u := fun p => (map_poly p).[u].
End Definitions.
Variables aR rR : ringType.
Section Combinatorial.
Variables (iR : ringType) (f : aR -> rR).
Local Notation "p ^f" := (map_poly f p) : ring_scope.

Lemma map_poly_comp_id0 (g : iR -> aR) p :
f 0 = 0 -> map_poly (f \o g) p = (map_poly g p)^f.