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)))))))