∀ {R : Type u_4} {ι : Type u_5} {A : Type u_2} {B : Type u_3} [inst : CommSemiring ι] [inst_1 : DecidableEq ι]
  [inst_2 : CommRing R] [inst_3 : Ring A] [inst_4 : Ring B] [inst_5 : Algebra R A] [inst_6 : Algebra R B]
  (𝒜 : ι → Submodule R A) (ℬ : ι → Submodule R B) [inst_7 : GradedAlgebra 𝒜] [inst_8 : GradedAlgebra ℬ]
  [inst_9 : Module ι (Additive ℤˣ)] {C : Type u_1} [inst_10 : Ring C] [inst_11 : Algebra R C] (f : A →ₐ[R] C)
  (g : B →ₐ[R] C),
  (LinearMap.mul' R C ∘ₗ TensorProduct.map f.toLinearMap g.toLinearMap ∘ₗ ↑(GradedTensorProduct.of R 𝒜 ℬ).symm) 1 = 1