R^2-irreducible universal covering spaces of P^2-irreducible open 3-manifolds
arXiv:math/9612215
Abstract
An irreducible open 3-manifold is {\bf R}-irreducible if every proper plane in splits off a halfspace. In this paper it is shown that if such a is the universal cover of a connected, {\bf P}-irreducible open 3-manifold with finitely generated fundamental group, then either is homeomorphic to {\bf R} or the group is a free product of infinite cyclic groups and infinite closed surface groups. Given any such finitely generated group uncountably many are constructed with that fundamental group such that their universal covers are {\bf R}-irreducible, are not homeomorphic to {\bf R}, and are pairwise non-homeomorphic. These results are related to the conjecture that closed, orientable, irreducible, aspherical 3-manifolds are covered by {\bf R}.