ScalingStacks

1.1.4. [0251]

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1.1.4.

By continuous metric on LL, we refer to a family h={|.|h​(x)}x∈Xanh=\{|\raisebox{1.72218pt}{.}|_{h}(x)\}_{x\in X^{\mathrm{an}}}, where |.|h​(x)|\raisebox{1.72218pt}{.}|_{h}(x) is a norm on L⊗𝒪Xκ^​(x)L\otimes_{\mathscr{O}_{X}}\hat{\kappa}(x) over κ^​(x)\hat{\kappa}(x) for each x∈Xanx\in X^{\mathrm{an}}, such that for any local basis ω\omega of LL over a Zariski open subset UU, |ω|h​(.)|\omega|_{h}(\raisebox{1.72218pt}{.}) is a continuous function on UanU^{\mathrm{an}}. We assume that XX is projective. Given a continuous metric hh on LL, we define a norm ‖.‖h\|\raisebox{1.72218pt}{.}\|_{h} on H0​(X,L)H^{0}(X,L) such that

∀s∈H0​(X,L),‖s‖h:=supx∈Xan|s|h​(x).\forall\,s\in H^{0}(X,L),\quad\|s\|_{h}:=\sup_{x\in X^{\mathrm{an}}}|s|_{h}(x).

Similarly, if YY is a closed subscheme of XX, we define a norm ‖.‖Y,h\|\raisebox{1.72218pt}{.}\|_{Y,h} on H0​(Y,L)H^{0}(Y,L) such that

∀l∈H0​(Y,L),‖l‖Y,h:=supy∈Yan|l|h​(y).\forall\,l\in H^{0}(Y,L),\quad\|l\|_{Y,h}:=\sup_{y\in Y^{\mathrm{an}}}|l|_{h}(y).

Clearly one has

(1) ‖s‖h⩾‖s|Y‖Y,h\|s\|_{h}\geqslant\|{\left.{s}\right|_{{Y}}}\|_{Y,h}

for any s∈H0​(X,L)s\in H^{0}(X,L).

∙\bullet In the following 1.1.5, 1.1.6 and 1.1.7, XX is always assumed to be projective.

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