The fixed point set of a finite group action on a homotopy four sphere (Q1824252)

This paper proves that if G is a finite group acting locally linearly and preserving orientation on a 4-dimensional \({\mathbb{Z}}\) homology sphere, then the fixed set of G is homeomorphic to a sphere. Further, if the fixed set is two points, then the local representations at the fixed points are the same. The paper briefly surveys the situation in all other dimensions, showing that dimension four is the remaining interesting case.