Investigation of all Ricci semi-symmetric and all conformally semi-symmetric spacetimes
arXiv:1006.5684 · doi:10.1088/1742-6596/314/1/012020
Abstract
We find all Ricci semi-symmetric as well as all conformally semi-symmetric spacetimes. Neither of these properties implies the other. We verify that only conformally flat spacetimes can be Ricci semi-symmetric without being conformally semi-symmetric and show that only vacuum spacetimes and spacetimes with just a -term can be Ricci semi-symmetric without being conformally semi-symmetric.
4 pages, 1 table