Skip to main content
edited tags
Link
Ali Taghavi
  • 356
  • 8
  • 31
  • 123
Source Link
Ali Taghavi
  • 356
  • 8
  • 31
  • 123

A closed manifold with a subset with the same ring cohomology

Is there an example of a closed manifold $M$ with a proper subset $A\subset M$ such the inclusion $i:A \to M$ gives a ring isomorphism $i^{*}$ between $\mathbb{Z}$-cohomologies?

In this question $A$ is merely a proper subset.(not necessarily compact, not necessarily submanifold)