Popa–Schnell's conjecture on direct images of pluricanonical bundles

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Let the base field be an algebraically closed field of characteristic zero. Let f:X→Yf:X\to Y be a morphism from a smooth projective variety XX to a smooth projective variety YY of dimension nn, and let L\mathcal L be an ample line bundle on YY. Popa–Schnell's conjecture. For every m≥1m\ge 1, the sheaf

f∗ωXm⊗Llf_*\omega_X^m\otimes\mathcal L^l

is generated by its global sections for l≥m(n+1)l\ge m(n+1). This conjecture is a relative form of Fujita's freeness conjecture for direct images of pluricanonical bundles; the paper generalizes the corresponding theorem to ample line bundles that are not globally generated and also studies positive characteristic.

References

Primary source

Sho Ejiri, “Notes on direct images of pluricanonical bundles”, arXiv:2210.05157 (2022).

Additional references

6 papers in this index state this conjecture (2014–2022). The statement above is taken from the most recent of them; the others are arXiv:1909.07000, arXiv:1712.08723, arXiv:1703.07279, arXiv:1701.08830, arXiv:1405.6125.

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