We extend the validity of the Penrose singularity theorem to spacetime metrics of regularity C1,1. The proof is based on regularisation techniques, combined with recent results in low regularity causality theory.
Cite
@article{arxiv.1502.00287,
title = {The Penrose singularity theorem in regularity $C^{1,1}$},
author = {Michael Kunzinger and Roland Steinbauer and James A. Vickers},
journal= {arXiv preprint arXiv:1502.00287},
year = {2016}
}