Generalized Prokhorov–Shokurov conjecture for generalized pairs

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Let (X′,B′+M′)(X',B'+M') be a generalized sub-pair with data X→X′X\to X' and MM, where B′B', M′M' and MM are Q\mathbb{Q}-divisors. Let f ⁣:X′→Z′f\colon X'\to Z' be a contraction such that

KX′+B′+M′∼Q,f0.K_{X'}+B'+M'\sim_{\mathbb{Q},f}0.

Assume that MM is semi-ample, let cc be the minimum positive integer such that ∣cM∣|cM| is basepoint-free, and assume that (X′,B′+M′)(X',B'+M') is generalized klt over the generic point of Z′Z'. Generalized Prokhorov–Shokurov conjecture. The moduli b-divisor MZ′\mathbf{M}_{Z'} is b-semi-ample; for the generic fiber Xη′X'_\eta of ff, there is an integer I0I_0 depending only on dim⁡Xη′\dim X'_\eta, the multiplicities of BhB^h, and cc such that

I0(KXη′+Bη′+Mη′)∼0,I_0(K_{X'_\eta}+B'_\eta+M'_\eta)\sim 0,

where the representative of M′M' may be replaced within its Q\mathbb{Q}-linear equivalence class; and MZ′\mathbf{M}_{Z'} is effectively b-semi-ample: there is a positive integer I1I_1 depending only on the dimension of X′X', the horizontal multiplicities of BB, and cc such that I1MZ′I_1\mathbf{M}_{Z'} is very b-semi-ample, namely I1MZ′=L‾I_1\mathbf{M}_{Z'}=\overline{L} for a basepoint-free divisor LL on some birational model of Z′Z'. This is proposed as a generalization of the Prokhorov–Shokurov conjecture in the setting of generalized pairs; its status is not resolved in the supplied source context.

References

Primary source

Stefano Filipazzi, “On a generalized canonical bundle formula and generalized adjunction”, arXiv:1807.04847 (2019).

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