ScalingStacks

Proof. [01ZN]

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Proof.

First note by Theorem 8.3 that if δ\delta is fixed, then there exists δ′​(v,δ)\delta^{\prime}({\rm v},\delta) such that if |Ric|≤3​δ′|{\rm Ric}|\leq 3\delta^{\prime} and if T0δ′=0T^{\delta^{\prime}}_{0}=0, then

|𝒱1δ′​(x)−ln⁡|Γ0||<δ.\displaystyle\big|\mathcal{V}^{\delta^{\prime}}_{1}(x)-\ln|\Gamma_{0}|\big|<\delta\,. (8.43)

By rescaling this inequality, we see that in the context of this lemma, the following holds. If x∈B1​(p)x\in B_{1}(p), α>α¯​(v,δ)\alpha>\bar{\alpha}(v,\delta) and

|𝒱4​rαδ​(x)−𝒱rα/4δ​(x)|<δ′,\displaystyle\big|\mathcal{V}^{\delta}_{4r_{\alpha}}(x)-\mathcal{V}^{\delta}_{r_{\alpha}/4}(x)\big|<\delta^{\prime}\,, (8.44)

then we have

|𝒱rαδ​(x)−ln⁡|Γα||<δ.\displaystyle\big|\mathcal{V}^{\delta}_{r_{\alpha}}(x)-\ln|\Gamma_{\alpha}|\big|<\delta\,. (8.45)

In particular, for x∈B1​(p)x\in B_{1}(p), we can apply Lemma 8.5 to see that there exists a scale α≤α¯​(v,δ)\alpha\leq\bar{\alpha}(v,\delta) such that

|Vrαδ​(x)−𝒱rα+1δ​(x)|<δ′,\displaystyle\big|V^{\delta}_{r_{\alpha}}(x)-\mathcal{V}^{\delta}_{r_{\alpha+1}}(x)\big|<\delta^{\prime}\,, (8.46)

and hence

|𝒱rαδ​(x)−ln⁡|Γα||<δ.\displaystyle\big|\mathcal{V}^{\delta}_{r_{\alpha}}(x)-\ln|\Gamma_{\alpha}|\big|<\delta\,. (8.47)

However, if

𝒱rαδ​(x)<ln⁡N−δ,\displaystyle\mathcal{V}^{\delta}_{r_{\alpha}}(x)<\ln N-\delta\,, (8.48)

this implies |Γα|<N|\Gamma_{\alpha}|<N, which completes the proof. ∎

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