Universal cover of a closed three-manifold with finite fundamental group
ID: universal-cover-of-a-closed-three-manifold-with-finite-fundamental-group
The universal cover of a connected closed manifold of dimension three with finite fundamental group is a closed simply connected three-manifold. It is orientable, since its orientation character has trivial domain. Its first integral homology vanishes, and the universal coefficient theorem for cohomology then gives . Integral Poincare duality gives , while and are . Thus it is an integral homology sphere. This proof does not require classifying simply connected three-manifolds.
New to topics? Read the docs here!