Fano varieties with large pseudoindex and non-free rational curves

Kiwamu Watanabe

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arXiv · 2309.03438

Fano varieties with large pseudoindex and non-free rational curves

Kiwamu Watanabe

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Abstract

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.

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BibTeX RIS

Kiwamu Watanabe. 2023-09-07. Fano varieties with large pseudoindex and non-free rational curves. https://arxiv.org/abs/2309.03438

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