On the Hamiltonian analysis of non-linear massive gravity

In this Letter we present a very simple and independent argument for the absence of the Boulware–Deser ghost in the recently proposed potentially ghost-free non-linear massive gravity. The limitation is that, in its simple form, the argument is, in a sense, non-constructive and less explicit than the standard approach. However, the formalism developed here may prove to be useful for discussing the formal aspects of the theory.