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 aimgM (f : ahom aT rT) U V : (f @: (U * V) = f @: U * f @: V)%VS.