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It is stated in may books and also in the wikipedia or WolframMathWorld that the Klein bottle is not homeomorphic to a subspace of $\mathbb R^3$. Why is it so?

Jochen
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1 Answers1

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If so, one could apply Alexander Duality to conclude that $$H_2(\text{Klein bottle},\mathbb{Z}) \approx \widetilde H_0(\mathbb{R}^3 - (\text{Klein bottle})) \approx \mathbb{Z} $$ contradicting that $H_2(\text{Klein bottle},\mathbb{Z})$ is trivial.

Lee Mosher
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