∀ {R : Type u_1} {A : Type u_2} {B : Type u_3} [inst : CommSemiring R] [inst_1 : Semiring A] [inst_2 : Semiring B]
  [inst_3 : Algebra R A] [inst_4 : Algebra R B] (f : A →ₗ[R] B) (a : A) (r : R),
  f ((algebraMap R A) r * a) = (algebraMap R B) r * f a