3 problems

A spacetime is a pair $(M,g)$, where $M$ is a differentiable manifold and $g$ is a smooth, symmetric, non-degenerate $(0,2)$-tensor field. Two spacetimes are isocausal when there a…

Let $(M,g)$ be a causal spacetime satisfying the No Observer Horizons condition (NOH). Its conformal group is denoted by $\mathrm{Conf}^\uparrow(M,g)$, and it is essential if there…

Let $(M,g)$ be a causal spacetime satisfying the NOH. The conformal group is denoted by $\mathrm{Conf}^\uparrow(M,g)$, and it is essential if there is no smooth positive function…