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arXiv · 2608.01577

The cubic threefold is symplectically irrational

Jiaji Cai
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Abstract

We prove that smooth cubic threefolds are symplectically irrational. This recovers the classical irrationality theorem of Clemens-Griffiths. The obstruction is given by the formal monodromy of the quantum connection around the irregular singularity.

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Jiaji Cai. 2026-08-03. The cubic threefold is symplectically irrational. https://arxiv.org/abs/2608.01577

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