Topological 4-manifolds with 4-dimensional fundamental group

Abstract

Let $\pi$ be a group satisfying the Farrell-Jones conjecture and assume that $B\pi$ is a 4-dimensional Poincar\'e duality space. We consider closed, topological, almost spin manifolds with fundamental group $\pi$ whose canonical map to $B\pi$ has degree 1 and show that two such manifolds are s-cobordant if and only if their equivariant intersection forms are isometric. If $\pi$ is good in the sense of Freedman, it follows that two such manifolds are homeomorphic if and only if they are homotopy equivalent. This shows rigidity in many cases that lie between aspherical 4-manifolds, where rigidity is expected by Borel's conjecture, and simply connected manifolds where rigidity is a consequence of Freedman's classification results.Comment: 12 page