Let \(M\) and \(N\) be smooth manifolds. Without using the de Rham Theorem, show that if the de Rham cohomology of \(M\) doesn’t vanish \(H^k_{\mathrm {dR}}(M)\ne \{0\}\) then \(H^k_{\mathrm {dR}}(M\times N)\ne \{0\}\).
Question
Math 6510 • Differentiable Manifolds
Fall 2019 • Question 3