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

Let the base field be an algebraically closed field of characteristic zero. Let f:XYf: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 m1m\ge 1, the sheaf

fωXmLlf_*\omega_X^m\otimes\mathcal L^l

is generated by its global sections for lm(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.

Sources & referencesView supporting material

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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