Although we have restricted ourselves to the case
of a vanishing cosmological constant this does not mean that other
cases have not been analyzed. Friedrich [63] has shown the
existence of asymptotically simple de Sitter type solutions of the
Einstein-Maxwell-Yang-Mills equations and stability of de Sitter
space. More recently [65], with the general
version of his conformal field equations, he was able to
demonstrate the existence of asymptotically simple anti-de Sitter
type solutions.
It should also be mentioned that some work has gone into generalizing the Bondi-Sachs calculations to poly-homogeneous space-times [34, 161, 162].
The structure of space-like infinity has been discussed here only in a rather cursory way. A very recent account of the relationship between static solutions and the role they play can be found in [53]. Readers who are interested in a more detailed treatment of the subject in general are referred to a recent review by Friedrich [69].