DLT extension conjecture

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Let (X,Δ)(X,\Delta) be a projective divisorial log terminal pair, with Δ\Delta a Q\mathbb{Q}-divisor, and write ⌊Δ⌋=S\lfloor\Delta\rfloor=S. Suppose that KX+ΔK_X+\Delta is nef and

KX+Δ∼QD≥0,K_X+\Delta\sim_{\mathbb{Q}}D\geq 0,

where S⊂Supp⁡DS\subset\operatorname{Supp}D. DLT extension conjecture. For all sufficiently divisible integers m≥2m\geq 2, the restriction map

H0(X,OX(m(KX+Δ)))→H0(S,OS(m(KX+Δ)))H^0\left(X,\mathcal{O}_X(m(K_X+\Delta))\right)\to H^0\left(S,\mathcal{O}_S(m(K_X+\Delta))\right)

is surjective.

The conjecture is an extension statement for sections from the reduced round-down divisor. The paper notes that it holds when KX+ΔK_X+\Delta is semi-ample and uses it in reductions concerning good minimal models.

References

Primary source

Osamu Fujino and Yoshinori Gongyo, “On log canonical rings”, arXiv:1302.5194 (2013).

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