The log canonical adjunction, effective log abundance, and effective adjunction conjectures

Let f ⁣:XZf\colon X\to Z be the fibre space and let DD, Θ\Theta, DdivD_{\operatorname{div}}, and DmodD_{\operatorname{mod}} be as in the paper's adjunction construction. Assume that DD and Θ\Theta are Q\mathbb{Q}-divisors, KX+ΘK_X+\Theta is Q\mathbb{Q}-linearly trivial over ZZ, and (F,(1t)DF+tΘF)(F,(1-t)D|_F+t\Theta|_F) is klt for every 0<t10<t\leq 1, where FF is the generic fibre. In particular, DdivD_{\operatorname{div}} and DmodD_{\operatorname{mod}} are Q\mathbb{Q}-divisors. Adjunction conjectures. The following assertions are expected: DmodD_{\operatorname{mod}} is b-semiample; if XηX_\eta is the generic fibre of ff, then I0(KXη+Dη)0I_0(K_{X_\eta}+D_\eta)\sim 0 for an integer I0I_0 depending only on dimXη\dim X_\eta and the multiplicities of DhD^{\mathrm h}; and DmodD_{\operatorname{mod}} is effectively b-semiample, meaning that there is a positive integer II, depending only on the dimension of XX and the horizontal multiplicities of DD, such that IDmodI D_{\operatorname{mod}} is very b-semiample, namely IDmod=MI D_{\operatorname{mod}}=\overline{M} for a base-point-free divisor MM on some model Z/ZZ'/Z. These assertions concern the expected positivity and effective control of the moduli part in canonical bundle adjunction; the cited theorem preceding them establishes only b-nefness under different klt hypotheses, so the conjectural semiampleness and effective bounds remain open in the supplied text.

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Primary source

Yu. G. Prokhorov and V. V. Shokurov, “Toward the second main theorem on complements: from local to global”, arXiv:math/0606242 (2007).

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