- Return the product of the monomials indexed by ``i`` and ``j``.
-
- This overrides the superclass method because here, both ``i``
- and ``j`` will be ordered pairs.
-
- SETUP::
-
- sage: from mjo.eja.eja_algebra import (QuaternionHermitianEJA,
- ....: RealSymmetricEJA)
-
- TESTS::
-
- sage: J1 = RealSymmetricEJA(1,field=QQ)
- sage: J2 = QuaternionHermitianEJA(1,field=QQ)
- sage: J = cartesian_product([J1,J2])
- sage: x = sum(J.gens())
- sage: x == J.one()
- True
- sage: x*x == x
- True
-