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Using Mayer-Vietoris to calculate the de Rham cohomology of the Möbius band $M$, what is the choice of separation?
i.e. $M=U\cup V$, which $U$ and $V$ well chosen for calculation?

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    What choices have you tried?2012-01-10
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    To summon the muses, you might consider computing the cohomology of a cylinder first.2012-01-10
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    Can you write the Möbius band as a union of two open disks, with intersection having two connected components?2012-01-10
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    It may also help to draw the band as a square with identifications made, i.e. to break up the square in a way that descends to the quotient. That way you don't have to picture a mobius band in your head.2012-01-11
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    (Of course, if the exercise doesn't require you to use Mayer-Vietoris, then there is a much easier way to get the answer...)2012-01-12
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    When comes to the cohomology of a cylinder boundary with two circle, I can separate the cylinder as two part U and V , both are homotopy equivalent to circle, and U intersecting V is also homotopy equivalent to a circle. am I right?2012-01-12
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    Yes. But the cilinder is also homotopy equivalent to the circle. So you already know the cohomology. You can also write it as the union of two contractible sets. The intersection contains two elements.2012-01-12

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