The refined Oort conjecture for cyclic covers of curves

Let kk be an algebraically closed field of characteristic p>0p>0. Let ϕ:ZX\phi: Z \xrightarrow{} X be a cyclic Γ\Gamma-cover of curves over kk, and let ϕ1:YX\phi_1: Y \xrightarrow{} X be its Galois sub-cover. Suppose Φ1:YRXR\Phi_1: \mathcal{Y}_R \xrightarrow{} \mathcal{X}_R is a lift of ϕ1\phi_1 to a finite extension R/W(k)R/W(k) in characteristic zero. The refined Oort conjecture. There exists a finite extension R/RR'/R and a lift Φ:ZRXR\Phi: \mathcal{Z}_{R'} \xrightarrow{} \mathcal{X}_{R'} of ϕ\phi over RR' that contains Φ1RR:YRXR\Phi_1 \otimes_R R': \mathcal{Y}_{R'} \xrightarrow{} \mathcal{X}_{R'} as a sub-cover. This refines the Oort conjecture by requiring a lift of a cyclic cover to extend a prescribed lift of its Galois sub-cover; the paper studies this lifting problem for wildly ramified covers, and the claim is presented as a conjecture.

Sources & referencesView supporting material

Primary source

Huy Dang, “The refined local lifting problem for cyclic covers of order four”, arXiv:2107.01780 (2023).

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