Karzhemanov's base point free conjecture for weak log Fano pairs

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Let XX be a projective algebraic variety of dimension at least 22 over C\mathbb{C}, and let DD be a Q\mathbb{Q}-boundary such that (X,D)(X,D) is log canonical and −(KX+D)-(K_X+D) is nef and big. Write ⌞D⌟\llcorner D\lrcorner for the reduced integral part of DD.

Karzhemanov's conjecture. Suppose that XX is Q\mathbb{Q}-factorial and

(KX+D)⋅Sdim⁡X−1⩾0(K_X+D)\cdot S^{\dim X-1}\geqslant 0

for every irreducible component S⊆⌞D⌟S\subseteq\llcorner D\lrcorner. Then the linear system

∣−n(KX+D)∣|-n(K_X+D)|

is free for n≫0n\gg 0.

The conjecture strengthens the paper's theorem by proposing base point freeness under a numerical condition on every component of the reduced boundary. The source presents it as a suggested correction to an earlier result; no resolution is supplied in the provided text.

References

Primary source

Ilya Karzhemanov, “One base point free theorem for weak log Fano threefolds”, arXiv:0906.0553 (2010).

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