Bing's example

From Wikipedia, the free encyclopedia

In topology, Bing's theorem asserts that there exists a topological space F which is not a manifold, but such that the Cartesian product F×R with the real line is homeomorphic to R4. In particular, this shows that the Cartesian product of a manifold with a non-manifold may still be a manifold. The result is not true for differentiable manifolds, however.

[edit] References