ScalingStacks

Lemma B.2 (Covering trick) . [01HX]

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Lemma B.2 (Covering trick).

Assume that kk is algebraically closed. Let ๐’ณ\mathcal{X} be an SNC SS-variety and denote by (Ei)iโˆˆI(E_{i})_{i\in I} the set of irreducible components of ๐’ณ0\mathcal{X}_{0}. Let also โ„’โˆˆPicโก(๐’ณ)\mathcal{L}\in\Pic(\mathcal{X}) and mโˆˆ๐โˆ—m\in\mathbf{N}^{*}. Then there exists an SNC SS-scheme ๐’ณโ€ฒ\mathcal{X}^{\prime} and a finite surjective morphism ฯ:๐’ณโ€ฒโ†’๐’ณ\rho:\mathcal{X}^{\prime}\to\mathcal{X} such that ฯโˆ—โ€‹โ„’\rho^{*}\mathcal{L} is divisible by mm in Picโก(๐’ณโ€ฒ)\Pic(\mathcal{X}^{\prime}) and ฯโˆ—โ€‹Ei\rho^{*}E_{i} is smooth over kk (but possibly disconnected) for all iโˆˆIi\in I.

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