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arXiv · 2601.15270

Global $+$-regularity of regular del Pezzo surfaces in mixed characteristic

Hirotaka Onuki
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Abstract

Let $R = W(k)$ be the ring of Witt vectors over an algebraically closed field $k$ of characteristic $p > 2$. Let $M$ be a three-dimensional regular integral flat projective $R$-scheme such that $H^0(M,\mathcal{O}_M) = R$ and the anticanonical sheaf $\omega_M^{-1}$ is ample. We show that $M$ is globally $+$-regular if the closed fiber $M_k$ is reduced.

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Hirotaka Onuki. 2026-01-21. Global $+$-regularity of regular del Pezzo surfaces in mixed characteristic. https://arxiv.org/abs/2601.15270

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