proposition: Lemma subalg_closedZ : subalg_closed -> submod_closed S.
proof: Proof. by case=> S1 Slin _; split; rewrite // -(subrr 1) linear_closedB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)