ScalingStacks

Lemma 4.9 . [02HC]

Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.

Complete original source context · Original author HTML

Lemma 4.9.

There exists ϵ0>0\epsilon_{0}>0 depending continuously on p1,…,pnp_{1},\dots,p_{n} and g𝕋g_{\mathbb{T}} such that for every ϵ<ϵ0\epsilon<\epsilon_{0} we have hϵ>12h_{\epsilon}>\tfrac{1}{2} on the complement of ⋃j=1kB8​ϵ​(qj)\bigcup_{j=1}^{k}{B_{8\epsilon}(q_{j})}.

Proof.

Restrict attention to the ball B2​ρ0​(qj)B_{2\rho_{0}}(q_{j}). First note that 1+ϵ⁡(mj−2)ρ≥1−2​ϵρ=341+\frac{\epsilon\,(m_{j}-2)}{\rho}\geq 1-\frac{2\epsilon}{\rho}=\tfrac{3}{4} for ρ=8​ϵ\rho=8\epsilon. Now choose ϵ0>0\epsilon_{0}>0 so that ϵ⁡(λj+C​ϵ264)≤14\epsilon(\lambda_{j}+C\tfrac{\epsilon^{2}}{64})\leq\tfrac{1}{4} for all ϵ≤ϵ0\epsilon\leq\epsilon_{0}. Here λj,C\lambda_{j},C are the constants of Lemma 4.7.(i). We conclude that hϵ>12h_{\epsilon}>\tfrac{1}{2} on ∂B8​ϵ​(qj)\partial B_{8\epsilon}(q_{j}) for ϵ<ϵ0\epsilon<\epsilon_{0}. Since hϵh_{\epsilon} blows up to +∞+\infty at the punctures qk+1,…,q8,±p1,…,±pnq_{k+1},\dots,q_{8},\pm p_{1},\dots,\pm p_{n} the maximum principle completes the proof. ∎

Original mathematics by the credited authors. Source-backed reader collection; mathematical self-containment is not assessed.