3 papers
math.AG2026
Irrational families of Fano weighted complete intersection fourfolds
Jiaji Cai, Andrew Harder, Sukjoo Lee
We study the irrationality of smooth Fano complete intersection fourfolds in weighted projective spaces, using an atom theoretic approach based solely on Gromov--Witten invariants.…
math.SG2026
The cubic threefold is symplectically irrational
Jiaji Cai
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…
math.SG2026
The quartic threefold is symplectically irrational
Jiaji Cai
We prove that smooth quartic threefolds are symplectically irrational: they cannot be related to projective space by a sequence of symplectic blow-ups, blow-downs, and deformations…