All Questions
Tagged with obstruction-theory vector-bundles
3 questions
15
votes
1
answer
1k
views
Possible mistake in Cohen notes "Immersions of manifolds and homotopy theory" (version 27 March 2022)
In Theorem 2 of these notes, Ralph Cohen reformulates the main theorem of Hirsch-Smale theory merely in terms of normal bundles.
In particular, he says that if $N, M$ are two manifolds, $\dim N< ...
7
votes
1
answer
735
views
Nowhere vanishing section implies reduction of structure group
Description
I noticed a repeating theme in vector bundle theory, and wonder if there's a theorem that describes this kind of phenomenon.
Given a vector bundle $E$ over a manifold $X$. If there is a ...
4
votes
0
answers
194
views
Obstruction to the existence of lifting of the classifying map
Let $E$ be an $n$-plane bundle over CW complex $X$. Then $E$ is a pullback of tautological bundle $\gamma_n$ over $BO(n)$ i.e. $E=f^*(\gamma_n)$. This $f$ is called classyfing map. One can show that ...