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arXiv 0801.3021math.AG
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有理同调射影平面上奇点的最大个数

The maximum number of singular points on rational homology projective planes

Dongseon Hwang, JongHae Keum

摘要:

一个正规射影复曲面称为有理同调射影平面,如果它与复射影平面$\mathbb{C}\mathbb{P}^2$具有相同的贝蒂数。已知具有商奇点的有理同调射影平面至多有5个奇点。到目前为止,所有已知的例子最多有4个奇点。本文证明了具有商奇点的有理同调射影平面$S$,除一种情况外,至多有4个奇点,使得$K_S$是nef。例外的情况来自Enriques曲面与9个光滑的有理曲线的Dynkin图的类型$ 3A_1 \oplus 2A_3$的配置。我们也得到了类似的结果,在可微的情况下,在辛的情况下,在一定的假设下,所有举行的代数情况。

英文摘要:

A normal projective complex surface is called a rational homology projective plane if it has the same Betti numbers with the complex projective plane $\mathbb{C}\mathbb{P}^2$. It is known that a rational homology projective plane with quotient singularities has at most 5 singular points. So far all known examples have at most 4 singular points. In this paper, we prove that a rational homology projective plane $S$ with quotient singularities such that $K_S$ is nef has at most 4 singular points except one case. The exceptional case comes from Enriques surfaces with a configuration of 9 smooth rational curves whose Dynkin diagram is of type $ 3A_1 \oplus 2A_3$. We also obtain a similar result in the differentiable case and in the symplectic case under certain assumptions which all hold in the algebraic case.

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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