Regular ambitoric 4-manifolds: from Riemannian Kerr to a complete classification (Q2025814)

The article under review represents an investigation of compact Riemannian 4-manifolds by a method of Killing 2-forms and topological analysis of moment maps, associated with the given manifold. The author discovers an ambitoric structure associated with the ring singularity of a type-D Kerr black hole, whose moment map is not locally convex near the ring singularity. Subsequently, he classifies regular ambitoric 4-orbifolds, supposing some completeness conditions.