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Lemma 4.4 .
For any δ 0 ≪ 1 \delta_{0}\ll 1 , there is a
constant
k 0 ≫ 1 k_{0}\gg 1 such that, if ‖ y ‖ h E ≤ 3 r 2 \|y\|_{h_{E}}\leq\frac{3r}{2} and ‖ σ ‖ C 1 , α ( L , h ) ≤ δ 0 \|\sigma\|_{C^{1,\alpha}(L,h)}\leq\delta_{0} , and k > k 0 k>k_{0} , then
‖ D σ 𝔉 k ( y , σ ) − D σ 𝔉 k ( 0 , 0 ) ‖ ≤ 1 2 C ¯ . \|D_{\sigma}\mathfrak{F}_{k}(y,\sigma)-D_{\sigma}\mathfrak{F}_{k}(0,0)\|\leq\frac{1}{2\overline{C}}.
Furthermore,
D σ 𝔉 k ( y , σ ) D_{\sigma}\mathfrak{F}_{k}(y,\sigma) is also invertible, and
‖ D σ 𝔉 k ( y , σ ) − 1 ‖ ≤ 2 C ¯ . \|D_{\sigma}\mathfrak{F}_{k}(y,\sigma)^{-1}\|\leq 2\overline{C}.