PMCV hypersurfaces in non-flat pseudo-Riemannian space forms

In this paper, we prove that PMCV (i.e. ⃗ is proportional to H⃗) hypersurface M^n_r of a non-flat pseudo-Riemannian space form Nⁿ⁺¹_s(c) with at most two distinct principal curvatures is minimal or locally isoparametric, and compute the mean curvature for the isoparametric ones. As an application, we give full classification results of such non-minimal Lorentzian hypersurfaces of non-flat Lorentz space forms.