proposition: Lemma subalg_closedBM : subalg_closed -> subring_closed S.
proof: Proof. by case=> S1 Slin SM; split=> //; apply: linear_closedB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)