ScalingStacks

Lemma 1.4 . [01DW]

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Lemma 1.4.

Let ฯ€:๐’ณโ€ฒโ†’๐’ณ\pi:\mathcal{X}^{\prime}\to\mathcal{X} be a vertical blow-up.

  • (i)

    There exists a ฯ€\pi-ample divisor AโˆˆDiv0โก(๐’ณโ€ฒ)A\in\Div_{0}(\mathcal{X}^{\prime}).

  • (ii)

    If โ„’โˆˆPicโก(๐’ณ)\mathcal{L}\in\Pic(\mathcal{X}) is ample then there exists mโˆˆ๐m\in\mathbf{N} such that ฯ€โˆ—โ€‹(mโ€‹โ„’|๐’ณK)\pi^{*}(m\mathcal{L}|_{\mathcal{X}_{K}}) extends to an ample line bundle โ„’โ€ฒ\mathcal{L}^{\prime} on ๐’ณโ€ฒ\mathcal{X}^{\prime}.

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