Canonical ahom_subType := Eval hnf in [subType for ahval].
Definition ahom_eqMixin := [eqMixin of ahom by <:].
Canonical ahom_eqType := Eval hnf in EqType ahom ahom_eqMixin.
Definition ahom_choiceMixin := [choiceMixin of ahom by <:].
Canonical ahom_choiceType := Eval hnf in ChoiceType ahom ahom_choiceMixin.
Fact linfun_is_ahom (f : {lrmorphism aT -> rT}) : ahom_in {:aT} (linfun f).

Lemma aimg_adjoin (f : ahom aT rT) U x : (f @: <<U; x>> = <<f @: U; f x>>)%VS.
Canonical ker_sub_ahom_aspace f g := ASpace (ker_sub_ahom_is_aspace f g).