2015/11/17 by William M. Goldman, Goldman, William M., Gregory Laun +1 · 1 citation
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Differential Geometry (math.DG) #FOS: Mathematics #Geometric Analysis and Curvature Flows #Geometric and Algebraic Topology #math.DG
paper · pdf · doi:10.48550/arxiv.1511.05228
17 pages, 5 figures
openalex publication_date 2015/11/17 · arxiv created 2016/04/05 · arxiv updated 2016/04/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A Margulis spacetime is a complete flat affine Lorentzian 3-manifold with free fundamental group. Associated to M is a noncompact complete hyperbolic surface Σ. We study double extensions of π1 (M) ≅ π1 (Σ) when Σ is homeomorphic to a projective plane minus two discs. We classify proper actions of this double extension on Minkowski space and show that there exist proper actions that do not admit crooked fundamental domains.