“…In fact, the result of [22] has been generalized to a large class of σ homogeneous of degree one (see in particular [2]). When the degree is greater than one, the analysis is less complete and often restricted to dimension two, see [6,5,34]; the results in general dimension concern specific choices of the speed [13,33,1] and all of them require a pinching condition on the initial hypersurface. The case where the degree is less than one is even more difficult.…”