Section SkewField.
Hypothesis fieldT : GRing.Field.mixin_of aT.
Fact agenv_is_aspace U : is_aspace (agenv U).
Canonical agenv_aspace U : {aspace aT} := ASpace (agenv_is_aspace U).
(* Kleene algebra properties *)

Lemma sub_agenv U : (U <= agenv U)%VS.