proposition: Lemma divringClosedP (divS : divringClosed R) : divring_closed divS.
proof: Proof. split; [ exact: rpred1 | exact: rpredB | exact: rpred_div ]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)