ScalingStacks

Proof. [0271]

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Proof.

First we consider the case n=1n=1. Fix l∈L⁡(x)∖{0}l\in{L(x)}\setminus\{0\}. For ϵ>0\epsilon>0, there is s∈V⊗kκ^​(x)s\in V\otimes_{k}\hat{\kappa}(x) such that s~​(x)=l\tilde{s}(x)=l and ‖s‖κ^​(x)≤eϵ​|l|h​(x)\|s\|_{\hat{\kappa}(x)}\leq e^{\epsilon}|l|_{h}(x).

Note that ‖e~‖h≤‖e‖\|\tilde{e}\|_{h}\leq\|e\| for all e∈Ve\in V. Let (e1,…,er)(e_{1},\ldots,e_{r}) be an e−ϵe^{-\epsilon}-orthogonal basis of VV with respect to ‖.‖\|\raisebox{1.72218pt}{.}\|. If we set s=a1​e1+⋯+ar​ers=a_{1}e_{1}+\cdots+a_{r}e_{r} (a1,…,ar∈κ^​(x)a_{1},\ldots,a_{r}\in\hat{\kappa}(x)), then, by Proposition 1.9,

‖s~‖h,κ^​(x)\displaystyle\|\tilde{s}\|_{h,\hat{\kappa}(x)} ≤max⁡{|a1|x​‖e~1‖h,…,|ar|x​‖e~r‖h}\displaystyle\leq\max\{|a_{1}|_{x}\|\tilde{e}_{1}\|_{h},\ldots,|a_{r}|_{x}\|\tilde{e}_{r}\|_{h}\}
≤max⁡{|a1|x​‖e1‖,…,|ar|x​‖er‖}\displaystyle\leq\max\{|a_{1}|_{x}\|e_{1}\|,\ldots,|a_{r}|_{x}\|e_{r}\|\}
≤eϵ​‖s‖κ^​(x),\displaystyle\leq e^{\epsilon}\|s\|_{\hat{\kappa}(x)},

so that

|l|hquot​(x)≤‖s~‖h,κ^​(x)≤eϵ​‖s‖κ^​(x)≤e2​ϵ​|l|h​(x),|l|_{h}^{\mathrm{quot}}(x)\leq\|\tilde{s}\|_{h,\hat{\kappa}(x)}\leq e^{\epsilon}\|s\|_{\hat{\kappa}(x)}\leq e^{2\epsilon}|l|_{h}(x),

and hence |l|hquot​(x)≤|l|h​(x)|l|_{h}^{\mathrm{quot}}(x)\leq|l|_{h}(x) by taking ϵ→0\epsilon\to 0. Thus the assertion for n=1n=1 follows from (1) in Lemma 3.5.

In general, by using (3) in Lemma 3.5,

|ln|hn​(x)=(|l|h​(x))n=(|l|hquot​(x))n≥|ln|hnquot​(x),|l^{n}|_{h^{n}}(x)=\left(|l|_{h}(x)\right)^{n}=\left(|l|_{h}^{\mathrm{quot}}(x)\right)^{n}\geq|l^{n}|_{h^{n}}^{\mathrm{quot}}(x),

and hence we have the assertion by (1) in Lemma 3.5. ∎

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