1204.5308 (Suhyoung Choi)

The topological and geometrical finiteness of complete flat Lorentzian
3-manifolds with free fundamental groups    [PDF]

Suhyoung Choi

We prove the topological tameness of a 3-manifold with a free fundamental group admitting a complete flat Lorentzian metric; i.e., a Margulis space-time isomorphic to the quotient of the complete flat Lorentzian space by the free and properly discontinuous isometric action of the free group of rank $\geq 2$. We will use our particular point of view that a Margulis space-time is a real projective manifold in an essential way. The basic tools are a bordification by a closed real projective surface with a free holonomy group, the important work of Goldman, Labourie, and Margulis on geodesics in the Margulis space-times and the 3-manifold topology. Finally, we show that Margulis space-times are geometrically finite under our definition.

View original: http://arxiv.org/abs/1204.5308