ScalingStacks

Remark 4.40 . [02QH]

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Remark 4.40.

The intersection multiplicity and the degree in the above Proposition only depend on the isomorphism class of the line bundles π’ͺ⁑(DΞ¨i){\mathcal{O}}(D_{\Psi_{i}}) and not on the 𝕋\mathbb{T}-Cartier divisors themselves. It is easy to check directly that the right-hand sides of (4.38) and (4.39) only depends on the isomorphism class of the line bundles. In fact, let LL be a toric line bundle generated by global sections and s1s_{1}, s2s_{2} two toric sections. For i=1,2i=1,2, set Di=div⁑(si)D_{i}=\operatorname{div}(s_{i}) and let Ξ¨i\Psi_{i} be the corresponding support function and Ξ”i\Delta_{i} the associated polytope. Then s2=Ο‡m​s1s_{2}=\chi^{m}s_{1} for some m∈Mm\in M. Thus Ξ¨2=Ξ¨1βˆ’m\Psi_{2}=\Psi_{1}-m and Ξ”2=Ξ”1βˆ’m\Delta_{2}=\Delta_{1}-m. Since the volume and the mixed volume are invariant under translation, we see that these formulae do not depend on the choice of sections.

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