Characterization conjecture for weighted projective spaces as Fano orbifolds

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Let Y\mathcal{Y} be a Fano orbifold of dimension nn. For ℓeau0000Z>0\ell eau0000\mathbb{Z}_{>0}, let g\binapi0(IY)g\bin a pi_0(I\mathcal{Y}), and let ff be a twisted map in Mor(1,g)(P1(1,ℓ),Y)\mathrm{Mor}_{(1,g)}(\mathbb{P}^1(1,\ell),\mathcal{Y}). Define

dg−1(f)=−KY⋅f∗P1(1,ℓ)+age⁡(g−1).d_{g^{-1}}(f)=-K_{\mathcal{Y}}\cdot f_*\mathbb{P}^1(1,\ell)+\operatorname{age}(g^{-1}).

Weighted-projective-space characterization conjecture. If, for every such ℓ\ell, gg, and ff,

dg−1(f)≥n+1,d_{g^{-1}}(f)\ge n+1,

then Y\mathcal{Y} is isomorphic to a finite quotient of a weighted projective space. The conjecture proposes a characterization of weighted projective spaces among Fano orbifolds; in the smooth case it is essentially the Mori–Mukai conjecture, proved by Cho, Miyaoka, and Shepherd-Barron. The general orbifold statement is therefore the unresolved extension proposed here.

References

Primary source

Chi Li and Zhengyi Zhou, “Minimal log discrepancy and orbifold curves”, arXiv:2502.11847 (2025).

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