EXPT defines real exponentiation for scalar-quantities. Specializes EXPT.
(=> (And (Scalar-Quantity ?X) (Real-Number ?R) (Expt ?X ?R ?Z)) (And (Scalar-Quantity ?Z) (=> (= ?R 0) (= ?Z 1)) (Forall (?U) (=> (Unit-Of-Measure ?U) (= (Expt (Magnitude ?X ?U) ?R) (Magnitude ?Z (Expt ?U ?R)))))))