Uniqueness of the scalar product in the tensor product of quaternion Hilbert modules

In the construction of a tensor product of quaternion Hilbert modules, given in a previous work (real, complex, and quaternionic), inner products were defined in the vector spaces formed from the tensor product of quaternion algebras H modulo an appropriate left ideal in each case. Under conditions that are necessary for the definition of a scalar product in the quaternionic Hilbert modules and a natural condition on the algebraic structure, it is proven that the scalar products which are defined are unique.