ScalingStacks

Example 2.2 . [02II]

Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.

Complete original source context Β· Original author HTML

Example 2.2.

Let X=β„™β„‚nX=\mathbb{P}^{n}_{\mathbb{C}} and L=π’ͺ⁑(1)L={\mathcal{O}}(1), the universal line bundle of β„™β„‚n\mathbb{P}^{n}_{\mathbb{C}}. A rational section ss of π’ͺ⁑(1){\mathcal{O}}(1) can be identified with a homogeneous rational function ρsβˆˆβ„‚β‘(x0,…,xn)\rho_{s}\in\mathbb{C}(x_{0},\dots,x_{n}) of degree 1. The poles of this section coincide which those of ρs\rho_{s}. For a point p=(p0:…:pn)βˆˆβ„™n(β„‚)p=(p_{0}:\dots:p_{n})\in\mathbb{P}^{n}(\mathbb{C}) outside this set of poles, the Fubini-Study metric of π’ͺ​(1)an{\mathcal{O}}(1)^{{\text{\rm an}}} is defined as

β€–s⁑(p)β€–FS=|ρs​(p0,…,pn)|(βˆ‘i|pi|2)1/2.\|s(p)\|_{\operatorname{FS}}=\frac{|\rho_{s}(p_{0},\dots,p_{n})|}{(\sum_{i}|p_{i}|^{2})^{1/2}}.

Clearly, this definition does not depend on the choice of a representative of pp. The pair (π’ͺ(1),βˆ₯β‹…βˆ₯FS)({\mathcal{O}}(1),\|\cdot\|_{{\operatorname{FS}}}) is a metrized line bundle.

Original mathematics by the credited authors. Source-backed reader collection; mathematical self-containment is not assessed.