New Homotopy 4-Spheres
arXiv:1101.2981
Abstract
We use surgery along 2-tori embedded in a union of two copies of a product of punctured 2-tori to produce a new collection of homotopy 4-spheres (4-manifolds homotopy equivalent to and hence homeomorphic to but possibly not diffeomorphic to ). It is still unknown if these new examples are in fact exotic.
11 pages, 5 figures