proposition: Lemma dvdrp_spec : forall p q, (p %| q) = (gcdsr p %| gcdsr q) && (pp p %| pp q).
proof: Proof. move=> p q. apply/idP/idP=> [H|]; first by rewrite gcdsr_inj_dvdr ?pp_inj_dvdr. by case/andP=> ? ?; rewrite (ppP p) (ppP q) dvdr_mul // polyC_inj_dvdr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(path choice fintype tuple finset ssralg) mathcomp(matrix poly) mathcomp(bigop polydiv) CoqEAL(stronglydiscrete dvdring)