proposition: Lemma gcdsr_inj_eqd : forall p q, p %= q -> gcdsr p %= gcdsr q.
proof: Proof. move=> p q; case/andP=> pq qp. by rewrite eqd_def (gcdsr_inj_dvdr pq) (gcdsr_inj_dvdr qp). 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)