∀ (R : Type u_4) (S : Type u_1) (A : Type u_2) (B : Type u_3) [inst : CommSemiring R] [inst_1 : CommSemiring S]
  [inst_2 : Semiring A] [inst_3 : Semiring B] [inst_4 : Algebra R A] [inst_5 : Algebra R B] [inst_6 : Algebra S A]
  [inst_7 : Algebra S B] [inst_8 : SMulCommClass R S A] [inst_9 : TensorProduct.CompatibleSMul R S A B]
  (x y : TensorProduct S A B),
  (Algebra.TensorProduct.mapOfCompatibleSMul R S A B) (x * y) =
    (Algebra.TensorProduct.mapOfCompatibleSMul R S A B) x * (Algebra.TensorProduct.mapOfCompatibleSMul R S A B) y