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arXiv math/0002101math.AG
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跳跃有理曲线的divisor阶

The degree of the divisor of jumping rational curves

Ziv Ran

摘要:

对于$¶^n$上秩为$r$和$c_1=a$的半稳定自反层$E$以及使得$r|ad$的整数$d$,我们给出了$E$对$d$次一般有理曲线的限制是平衡的充分条件,即平凡丛的扭曲(例如,如果$E$在一般线上具有平衡限制,或者$r=2$或$E$是切丛的外幂)。假设这一点,我们给出了一个公式的“虚拟度”,解释枚举,轨迹的有理曲线的程度$d$上的限制$E$是不平衡的,推广了一个经典的公式,由于巴斯的程度的除数跳跃线的一个半稳定的秩-2丛。

英文摘要:

For a semistable reflexive sheaf $E$ of rank $r$ and $c_1=a$ on $¶^n$ and an integer $d$ such that $r|ad$, we give sufficient conditions so that the restriction of $E$ on a generic rational curve of degree $d$ is balanced, i.e. a twist of the trivial bundle (for instance, if $E$ has balanced restriction on a generic line, or $r=2$ or $E$ is an exterior power of the tangent bundle). Assuming this, we give a formula for the 'virtual degree', interpreted enumeratively, of the locus of rational curves of degree $d$ on which the restriction of $E$ is not balanced, generalizing a classical formula due to Barth for the degree of the divisor of jumping lines of a semistable rank-2 bundle.

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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