proposition: Lemma sdivr_closed_div : sdivr_closed -> divr_closed.
proof: Proof. by case=> SN1 Sdiv; split; rewrite // -(divrr (@unitrN1 _)) Sdiv. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)