proposition: Lemma divpD d p q : (p + q) %/ d = p %/ d + q %/ d.
proof: Proof. have [-> | dn0] := eqVneq d 0; first by rewrite !divp0 addr0. by apply: IdomainUnit.divpD; rewrite unitfE lead_coef_eq0. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)