proposition: Fact phi_is_rmorphism : multiplicative phi.
proof: Proof. split=> [p q|]; apply/polyP=> i; last by rewrite coef_map !coef1. by rewrite coefMr coef_map coefM; apply: eq_bigr => j _; rewrite !coef_map. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype finfun perm matrix bigop zmodp mxalgebra) mathcomp(choice poly polydiv mxpoly binomial)