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arXiv 2309.03438math.AGmath.CVmath.DG
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具有大伪指标和非自由有理曲线的 Fano 簇

Fano varieties with large pseudoindex and non-free rational curves

Kiwamu Watanabe

AI总结:

本文分类了非自由有理曲线最小反典范次数至少为 $n-2$ 的复光滑 Fano $n$ 重折叠的极值收缩,完成了伪指标至少为 $n-2$ 且 Picard 数大于 1 的 Fano 簇分类,并探讨了伪指标与其他不变量的关系。

摘要:

对于 $n\geq 4$,设 $X$ 为复光滑 Fano $n$ 重折叠,其上非自由有理曲线的最小反典范次数至少为 $n-2$。我们对这类簇的极值收缩进行了分类。作为应用,我们获得了伪指标和 Picard 数均大于 1 的 Fano 四重折叠的分类。结合此结果与先前结果,我们完成了对伪指标至少为 $n-2$ 且 Picard 数大于 1 的光滑 Fano $n$ 重折叠的分类。这可视为对先前多项结果的推广。我们还讨论了伪指标与 Fano 簇其他不变量之间的关系。

英文摘要:

For $n\geq 4$, let $X$ be a complex smooth Fano $n$-fold whose minimal anticanonical degree of non-free rational curves on $X$ is at least $n-2$. We classify extremal contractions of such varieties. As an application, we obtain a classification of Fano fourfolds with pseudoindex and Picard number greater than one. Combining this result with previous results, we complete the classification of smooth Fano $n$-folds with pseudoindex at least $n-2$ and Picard number greater than one. This can be seen as a generalization of various previous results. We also discuss the relations between pseudoindex and other invariants of Fano varieties.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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