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Results tagged with characteristic-classes
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user 144250
Cohomology classes associated to vector bundles. Includes Stiefel-Whitney classes, Chern classes, Pontryagin classes, and the Euler class.
6
votes
1
answer
280
views
Why does Bott's obstruction theorem imply the vanishing of some cohomology classes of $B\Gam...
Recall that Bott's obstruction for integrability [Bott70] asserts that:
Given a smooth (=$C^\infty$) $m$-manifold $M$ and a completely integrable vector subbundle $E\subset TM$ of rank $m-q$, every p …
- 2,292
6
votes
Accepted
Why does Bott's obstruction theorem imply the vanishing of some cohomology classes of $B\Gam...
This is explained very nicely in [Law77]. Here is a sketch.
We will use the following crucial lemma.
Lemma (Haefliger). Let $M$ be a smooth manifold and let $\mathcal{H}$ be a $\Gamma_q$-structure on …
- 2,292