ScalingStacks

Proposition 3.8 . [0274]

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Proposition 3.8.

We assume that there is a subspace HH of H0โ€‹(X,L)H^{0}(X,L) such that HโŠ—k๐’ชXโ†’LH\otimes_{k}\mathscr{O}_{X}\to L is surjective and the morphism ฯ•H:Xโ†’โ„™โก(H)\phi_{H}:X\to\mathbb{P}(H) induced by HH is a closed embedding. We identify XX with ฯ•Hโ€‹(X)\phi_{H}(X), so that L=๐’ชโ„™โก(H)โ€‹(1)|XL=\left.{\mathscr{O}_{\mathbb{P}(H)}(1)}\right|_{{X}}. Let โ€–.โ€–\|\raisebox{1.72218pt}{.}\| be a norm of HH such that HH has an orthonormal basis (e1,โ€ฆ,er)(e_{1},\ldots,e_{r}) with respect to โ€–.โ€–\|\raisebox{1.72218pt}{.}\|. We set

h:={|.|(H,โ€–.โ€–)quotโ€‹(x)}xโˆˆXanandโ„‹:=๐”ฌkโ€‹e1+โ‹ฏ+๐”ฌkโ€‹er=(H,โ€–.โ€–)โ‰ค1.h:=\left\{|\raisebox{1.72218pt}{.}|^{\mathrm{quot}}_{(H,\|\raisebox{1.20552pt}{.}\|)}(x)\right\}_{x\in X^{\mathrm{an}}}\quad\text{and}\quad\mathscr{H}:=\mathfrak{o}_{k}e_{1}+\cdots+\mathfrak{o}_{k}e_{r}=(H,\|\raisebox{1.72218pt}{.}\|)_{\leq 1}.

Let ๐’ณ\mathscr{X} be the Zariski closure of XX in โ„™โก(โ„‹)\mathbb{P}(\mathscr{H}) (cf. ยง1.1.7) and โ„’:=๐’ชโ„™โก(โ„‹)โ€‹(1)|๐’ณ\mathscr{L}:=\left.{\mathscr{O}_{\mathbb{P}(\mathscr{H})}(1)}\right|_{{\mathscr{X}}}. Then |.|hโ€‹(x)=|.|โ„’โ€‹(x)|\raisebox{1.72218pt}{.}|_{h}(x)=|\raisebox{1.72218pt}{.}|_{\mathscr{L}}(x) for all xโˆˆXanx\in X^{\mathrm{an}}.

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