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Geoffroy Horel
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What manifolds are boundaries of euclidian spaces ?

I would like to know if there are compact (n-1)-manifolds $N$ that are not spheres but such that there is a manifold with boundary $M$ which satisfies the following two properties:

  • $\partial M\cong N$

  • $M-\partial M\cong \mathbb{R}^n$

I am primarily interested in this question in the category of smooth manifolds but I would be interested to know the answer in the topological case as well.

Geoffroy Horel
  • 2.7k
  • 18
  • 22