proposition: Lemma modpZl c p q : (c *: p) %% q = c *: (p %% q).
proof: Proof. have [-> | qn0] := eqVneq q 0; first by rewrite !modp0. by apply: IdomainUnit.modpZl; rewrite unitfE lead_coef_eq0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)