ScalingStacks

Example 1 [03XG]

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Example 1

Let X=๐€1=Sโ€‹pโ€‹eโ€‹cโ€‹(Kโก[x])X={\bf A}^{1}=Spec(K[x]) be the affine line. The analytic space Xaโ€‹nX^{an} contains, among others, points of the following types:

  • โ€ข

    Xโก(K)โ†ชXโก(Kยฏ)/Gโ€‹aโ€‹lโ€‹(Kยฏ/K)โ†ชXaโ€‹nX(K)\hookrightarrow X(\overline{K})/Gal(\overline{K}/K)\hookrightarrow X^{an};

  • โ€ข

    for rโˆˆ๐‘โ‰ฅ0r\in{{\bf R}}_{\geq 0} define

    |โˆ‘j=0dcjโ€‹zj|r:=maxjโก(|cj|โ€‹rj).|\sum_{j=0}^{d}c_{j}z^{j}|_{r}:=\max_{j}(|{c_{j}}|r^{j})\,\,.

    This gives an embedding ๐‘โ‰ฅ0โ†ชXaโ€‹n{\bf R}_{\geq 0}\hookrightarrow X^{an}.

We see that Xaโ€‹nX^{an} contains, in a sense, both pp-adic and real points.

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