The effective anticanonical divisor conjecture for global log canonical thresholds

Let XX be a del Pezzo variety with log terminal singularities, and let lct(X)\mathrm{lct}(X) denote its global log canonical threshold. An effective Q\mathbb{Q}-divisor DD on XX is anticanonically equivalent when it is Q\mathbb{Q}-linearly equivalent to KX-K_X.

Effective anticanonical divisor conjecture. There is an effective Q\mathbb{Q}-divisor DD on XX such that

DQKXD\sim_{\mathbb{Q}}-K_X

and

lct(X)=lct(X,D).\mathrm{lct}(X)=\mathrm{lct}(X,D).

The claim would reduce the computation of the global log canonical threshold to the log canonical threshold of a single effective anticanonical Q\mathbb{Q}-divisor. The surrounding discussion notes that rationality of global log canonical thresholds is unknown even for del Pezzo surfaces with log terminal singularities; no resolution of this conjecture is given here.

Sources & referencesView supporting material

Primary source

Ivan Cheltsov, Jihun Park and Constantin Shramov, “Exceptional del Pezzo hypersurfaces”, arXiv:0810.2704 (2009).

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