Relation between tangent bundle of a manifold and it’s covering manifold

complex-geometrysmooth-manifoldsvector-bundles

Let $M$ be a smooth (or complex) manifold, $N$ — topological manifold and $p: M \to N$ covering map. Consider the smooth (complex) structure on $N$ obtained by the well-known procedure making $p$ into smooth (holomorphic) map.

Is that true that from triviality of the (holomorphic) tangent bundle $TM$ follows triviality of $TN$? Is there any relation between those two whatsoever?

Best Answer

Triviality of $TM$ does not imply that of $TN$. For example, let $M=\mathbb R^2$, and let $\mathbb Z$ act on $M$ by $$ n\cdot (x,y) = (x+n,(-1)^n y). $$ Let $N$ be the quotient space $M/\mathbb Z$, and let $p:M\to N$ be the quotient map. Then $p$ is a smooth covering map, and $N$ is diffeomorphic to the open Möbius band, which is not even orientable, let alone parallelizable.

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