Shokurov's effective moduli-part conjecture for Fano type fibrations

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Let f ⁣:X→Yf\colon X\to Y be a proper surjective morphism with connected fibers between normal varieties, with X/YX/Y of relative Fano type. Let Δ\Delta be a Q\mathbb Q-divisor on XX such that

KX+Δ=f∗LK_X+\Delta=f^*L

for some Q\mathbb Q-divisor LL on YY. Write

KX+Δ=f∗(KY+R+B),K_X+\Delta=f^*(K_Y+R+B),

where RR is the discriminant part and BB is the moduli part.

Shokurov's conjecture. If (X,Δ)(X,\Delta) is ϵ\epsilon-log terminal, then there exists δ=δm,n(ϵ)>0\delta=\delta_{m,n}(\epsilon)>0 and an effective moduli part BB such that (Y,R+B)(Y,R+B) is δ\delta-log terminal.

This is a stronger refinement of the epsilon-delta conjecture, incorporating the discriminant and moduli parts supplied by subadjunction. Its resolution status is not specified in the supplied text.

References

Primary source

Valery Alexeev and Alexander Borisov, “On the Log Discrepancies in Toric Mori Contractions”, arXiv:1208.3271 (2013).

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