proposition: Lemma eqp_mul2l r p q: r != 0 -> (r * p %= r * q) = (p %= q).
proof: Proof. by move=> nz_r; rewrite /eqp !dvdp_mul2l. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop ssralg poly)