Lie theory for asymptotic symmetries in general relativity: The NU group

We study the Newman--Unti (NU) group from viewpoint of infinite-dimensional geometry. The NU is a topological in natural coarse topology, but it does not become manifold and hence Lie this topology. To obtain structure we consider finer Whitney-type This turns unit component into an group. then theoretic properties Surprisingly, operations full discontinuous, whence support structure. contains Bondi--Metzner--Sachs (BMS) as subgroup, whose was constructed previous article. It well known that algebra splits direct sum ideals algebras BMS conformal rescalings scri. However, lack on implies cannot be embedded subgroup therein.