### Conveners

#### Parallel session 7 (Mathematical Relativity)

- Session convener: Filipe Mena

Siklos space-times conform an interesting class of exact solutions of General Relativity. In particular, they represent idealized gravitational waves propagating on top of anti-de Sitter space-times. In this talk, I will present a generalization of them, which are naturally called generalized Siklos space-times. I will motivate their introduction, elaborate on the curvature of these...

There is growing interest in understanding the radiative properties of particular classes of null hypersurfaces in space-time, such as weakly isolated horizons, from the viewpoint of the structure available at the conformal boundary of asymptotically flat space-times. In this work, a covariant definition of news tensor is given for general null hypersurfaces with arbitrary cosmological...

We present a new and effective method of algebraic classification of 2+1 geometries. It parallels the approach of Newman and Penrose, and in our work, we extend this formalism into three dimensions. The spacetimes are classified into the types I, II, D, III, N and O using appropriate scalars constructed from the Cotton tensor, which are analogous to the Newman–Penrose scalars of the Weyl...