ScalingStacks

Proof. [02PZ]

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Proof.

We have already shown that a 𝕋\mathbb{T}-Cartier divisor produces a toric line bundle with a toric section. Let now ((L,z),s)((L,z),s) be a toric line bundle equipped with a toric section and Ξ£\Sigma the fan that defines XX. Since every line bundle on an affine toric variety is trivial, for each ΟƒβˆˆΞ£\sigma\in\Sigma we can find a section sΟƒs_{\sigma} that generates LL on XΟƒX_{\sigma} and such that sσ​(x0)=zs_{\sigma}(x_{0})=z. Since ss is regular and nowhere vanishing on X0X_{0} and s⁑(x0)=zs(x_{0})=z, we can find elements mΟƒβˆˆMm_{\sigma}\in M such that s=Ο‡βˆ’mσ​sΟƒs=\chi^{-m_{\sigma}}s_{\sigma}, because any regular nowhere vanishing function on a torus is a constant times a monomial. The elements mΟƒm_{\sigma} glue together to define a virtual support function Ξ¨\Psi on Ξ£\Sigma that does not depend on the chosen trivialization. It is easy to see that the correspondence (L,s)↦DΞ¨(L,s)\mapsto D_{\Psi} is the inverse of the previous one, which proves the theorem. ∎

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