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Question

Math 6510 • Differentiable Manifolds

Winter 2005 • Question 10

Let \(X\) and \(Y\) be two closed oriented manifolds. Prove that Euler characteristic is multiplicative, i.e. that \[ \chi (X\times Y)=\chi (X)\times \chi (Y). \] You may not appeal to the Kunneth formula.

Raw LaTeX

Let \(X\) and \(Y\) be two closed oriented manifolds. Prove that Euler characteristic
is multiplicative, i.e. that
\[
  \chi(X\times Y)=\chi(X)\times\chi(Y).
\]
You may not appeal to the Kunneth formula.