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A semiampleness result for hyperkähler fourfolds and smoothings of Lagrangian subvarieties
Abstract
We give a geometric proof of the following statement: let X be a smooth hyperkähler fourfold such that the Picard group is generated by a line bundle L that is nef, non-trivial, and not big. If the Kodaira dimension of L is non-negative, some positive multiple defines a Lagrangian fibration. The proof requires a number of tools which are of independent interest, including an analogue of Voisin's unobstructedness result and a smoothing result for singular Lagrangian subvarieties.
Related
- Lagrangian fibrations on hyperkahler manifolds have no multiple fibers in codimension one
- Semiampleness on Jacobian elliptic surfaces of Kodaira dimension one
- Normal complex surface singularities with rational homology disk smoothings
- Convergence of spectral smoothings from compact quantum group actions
- Weighted homogeneous surface singularities admitting rational homology disk smoothings
BibTeX
@misc{horing2026semiampleness,
title = {{A semiampleness result for hyperkähler fourfolds and smoothings of Lagrangian subvarieties}},
author = {Andreas Höring and Vladimir Lazić and Christian Lehn},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31497},
eprint = {2610.31497},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31497},
}
RIS
TY - UNPB
TI - A semiampleness result for hyperkähler fourfolds and smoothings of Lagrangian subvarieties
AU - Andreas Höring
AU - Vladimir Lazić
AU - Christian Lehn
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31497
UR - https://arxiv.org/abs/2610.31497
AB - We give a geometric proof of the following statement: let X be a smooth hyperkähler fourfold such that the Picard group is generated by a line bundle L that is nef, non-trivial, and not big. If the Kodaira dimension of L is non-negative, some positive multiple defines a Lagrangian fibration. The proof requires a number of tools which are of independent interest, including an analogue of Voisin's unobstructedness result and a smoothing result for singular Lagrangian subvarieties.
ER -