Section AspaceTheory.
Variables (K : fieldType) (aT : FalgType K).
Implicit Types (u v e : aT) (U V : {vspace aT}) (A B : {aspace aT}).

Lemma algid_subproof U :
{e | e \in U
& has_algid U ==> (U <= lker (amull e - 1) :&: lker (amulr e - 1))%VS}.