Wang claims that based on the principle of relativity and Fermat's principle a light-momentum criterion is set up, stating that "the momentum of light in a medium is parallel to the wave vector in all inertial frames of reference", and "this light-momentum criterion provides a necessary physical condition to find out whether a mathematical expression can represent the correct momentum of light". Because Minkowski photon momentum and energy constitute a Lorentz four-vector, given by (Lorentz invariant) Planck constant formula_12 multiplied by wave four-vector formula_13, the Minkowski momentum is parallel to the wave vector in all inertial frames, and thus it meets light-momentum criterion. However Partanen and coworkers disagree, criticizing: Wang's theory "neglects the transferred mass formula_14, thus leading to mathematical problems", and "the neglectance of the transferred mass formula_14 … in turn leads to complicated mathematics without providing transparent and physically insightful covariant theory of light".