A smooth 4-manifold homeomorphic yet not diffeomorphic to euclidean space
It is not known (as of 2021) whether or not there are any exotic 4-spheres; such an exotic 4-sphere would be a counterexample to the smooth generalized Poincaré conjecture in dimension 4. Some plausible candidates are given by Gluck twists.
Rockefeller Plaza, San Francisco, S.F.
News Directory is a collection of powerful news brands that deliver top stories on our platform.
Terms & Policies