Effective b-semiampleness conjecture
Effective b-semiampleness conjecture
Let be a nonnegative integer and let be a rational dcc subset. For a -contraction under the assumptions cited in the source, write for its moduli b-divisor. A b-divisor is b-free if it is the closure of a base point free divisor on some model of .
Effective b-semiampleness conjecture. There exists a positive integer such that, for every such -contraction with and , is b-free:
Here is a base point free divisor on some model of . Equivalently, is an Alexeev log pair of index . The same is expected for -contractions of Alexeev pairs of index , with depending also on .
This conjecture would provide effective semiampleness for the moduli part in the adjunction framework and is intended to support reductions to finite-type and Calabi–Yau cases. The source attributes it to PSh08 and leaves it open.
Sources & referencesView supporting material
Primary source
V. V. Shokurov, “Existence and boundedness of n-complements”, arXiv:2012.06495 (2020).
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