Is $\mathbb{C}^{n+1}$ \ $\{0\}$ isomorphic to $\mathbb{P}^n\times \mathbb{C}^*$?
Where $\mathbb{P}^n$ is $n$-dimensional complex projective space, $\mathbb{C}^*=\mathbb{C}$ \ $\{0\}$.
My idea:
- Under the classical topology, the $\pi_1(\mathbb{C}^{n+1})=\{e\}$ but $\pi_1(\mathbb{P}^n\times \mathbb{C}^*)=\mathbb{Z}$. hence their classical topologies are not homeomorphic. The regular map is clearly continuous, hence if they are isomorphic(as two varieties), they will be homeomorphic, this can't be true.
- The above idea is effective but not algebraic geometrical. Is there some algebraic geometrical way to prove $\mathbb{C}^{n+1}$ \ $\{0\}$ is not isomorphic to $\mathbb{P}^n\times \mathbb{C}^*$?
(I haven't learned about "scheme", can somebody tell me in basic language?)
$\mathbb{C}^{n+1}$ \ $\{0\}$ is the tautological line bundle (with the zero section removed), whereas $\mathbb{P}^n\times \mathbb{C}^*$ is the trivial line bundle (with the zero section removed). The tautological line bundle is known to be non-trivial. For example, for $n=1$ one gets the Hopf bundle if one considers vectors of unit length.