∀ {R : Type u} [inst : CommRing R] {K L M N : AlgCat R} (f : K ⟶ L) (g : M ⟶ N),
  AlgCat.Hom.hom (CategoryTheory.MonoidalCategoryStruct.tensorHom f g) =
    Algebra.TensorProduct.map (AlgCat.Hom.hom f) (AlgCat.Hom.hom g)