Computing Riemann-Roch polynomials and classifying hyper-K\'ahler fourfolds
| Autor: | Debarre, Olivier, Huybrechts, Daniel, Macrì, Emanuele, Voisin, Claire |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | J. Amer. Math. Soc. 37 (2024), 151-185 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1090/jams/1016 |
| Popis: | We prove that a hyper-K\"ahler fourfold satisfying a mild topological assumption is of K3$^{[2]}$ deformation type. This proves in particular a conjecture of O'Grady stating that hyper-K\"ahler fourfolds of K3$^{[2]}$ numerical type are of K3$^{[2]}$ deformation type. Our topological assumption concerns the existence of two integral degree-2 cohomology classes satisfying certain numerical intersection conditions. There are two main ingredients in the proof. We first prove a topological version of the statement, by showing that our topological assumption forces the Betti numbers, the Fujiki constant, and the Huybrechts-Riemann-Roch polynomial of the hyper-K\"ahler fourfold to be the same as those of K3$^{[2]}$ hyper-K\"ahler fourfolds. The key part of the article is then to prove the hyper-K\"ahler SYZ conjecture for hyper-K\"ahler fourfolds for divisor classes satisfying the numerical condition mentioned above. Comment: 34 pages. v3: Minor corrections, references updated |
| Databáze: | arXiv |
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