“…At this stage one can often be quite general, using only generic features of the class of solutions under consideration, and non-committing to a precise space M D−d . In the second stage one This fact has already been used in several cases, to infer properties of the corresponding operator spectrum, without performing the full KK reduction; see for example [14,15,16,17,18,19] for AdS 4 solutions. In particular, [17] showed in general the above statement about the spin-2 mass operator, drawing on earlier results by [20], and their arguments can be applied also to our case.…”