Null weak singularities in plane-symmetric space-times

We construct a class of plane-symmetric solutions possessing a curvature singularity that is null and weak, like the space-time singularity at the Cauchy horizon of spinning (or charged) black holes. We then analyze the stability of this singularity using a rigorous nonperturbative method. We find that within the framework of (linearly polarized) plane-symmetric space-times this type of null weak singularity is locally stable. Generically, the singularity is also scalar curvature. These observations support the new picture of the null weak singularity inside spinning (or charged) black holes, which is so far established primarily on the perturbative approach.