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6.2.3 C 0 -convergence of the potential [004V]

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6.2.3 C0C^{0}-convergence of the potential

It remains to show

Proposition 6.5.

Up to slightly shrinking the domains, the Calabi-Yau metrics on UJ,tU_{J,t} admit local potential functions ϕC​Y,J,t\phi_{CY,J,t} such that ωC​Y,t=d​dc​ϕC​Y,J,t\omega_{CY,t}=dd^{c}\phi_{CY,J,t}, and ‖ϕC​Y,J,t−ϕ0∘Log𝒳‖C0→0\left\lVert\phi_{CY,J,t}-\phi_{0}\circ\text{Log}_{\mathcal{X}}\right\rVert_{C^{0}}\to 0 as t→0t\to 0.

Prop. 6.4 says that the local potential of ωψ,t\omega_{\psi,t} and ϕ0∘Log𝒳\phi_{0}\circ\text{Log}_{\mathcal{X}} differ negligibly in the t→0t\to 0 limit in the C0C^{0}-sense. Ideally, one would like to use some version of L1L^{1}-volume stability to conclude the C0C^{0}-smallness of the relative potential between ωψ,t\omega_{\psi,t} and ωC​Y,t\omega_{CY,t}. Unfortunately, due to the difficulty of regularization in the non-generic region, there is very little control on the volume density of ωψ,t\omega_{\psi,t} in the non-generic region, and we cannot conclude a Skoda type estimate like (11) for ωψ,t\omega_{\psi,t}. This technical problem causes an asymmetry between ωψ,t\omega_{\psi,t} and ωC​Y,t\omega_{CY,t}, and only ‘one half’ of the L1L^{1}-volume stability estimate (cf. section 4.3) applies, which is why we designed Theorem 4.7.

After the dust settles, Theorem 4.7 implies that ϕC​Y,J,t−ϕ0∘Log𝒳\phi_{CY,J,t}-\phi_{0}\circ\text{Log}_{\mathcal{X}} concentrates near its minimum value (normalized to be zero) on a subset with almost 100%100\% of the Calabi-Yau measure (cf. [53, Prop 4.4, Cor. 4.6]). More precisely, for any given small number κ,λ≪1\kappa,\lambda\ll 1, then for sufficiently small tt, the measure

d​μt​(ϕC​Y,J,t−ϕ0∘Log𝒳≥κ/4)<λ.d\mu_{t}(\phi_{CY,J,t}-\phi_{0}\circ\text{Log}_{\mathcal{X}}\geq\kappa/4)<\lambda. (21)

On a slightly shrinked version of UJ,tU_{J,t}, this can be improved to the C0C^{0}-control

0≤ϕC​Y,J,t−ϕ0∘Log𝒳<κ,0\leq\phi_{CY,J,t}-\phi_{0}\circ\text{Log}_{\mathcal{X}}<\kappa,

by a slightly tricky application of the mean value inequality (cf. [53, Thm. 4.7]). Since κ\kappa is arbitrary, this achieves Prop. 6.5, which verifies the hypothesis of Prop. 6.5, whence the weak metric version of the SYZ conjecture.

Remark 16.

The C0C^{0} convergence statement only applies to the generic region. We do not know the answer to

Question 7.

Do the potentials of the CY metrics on XtX_{t} converge to the NA CY metric ‖⋅‖C​Y\left\lVert\cdot\right\rVert_{CY} on XKa​nX_{K}^{an} globally in the hybrid topology?

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