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arXiv 1107.4545math.AGmath.CV
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log Fano簇上的正则极化流形族

Families of canonically polarized manifolds over log Fano varieties

Daniel Lohmann

摘要:

设(X,D)是dlt对,其中X是正规投射簇.设S表示D的下舍入的支集,K表示X的典范除子.我们证明了X§上的正则极化簇的光滑族是等平凡的,如果因子-(K+D)是充足的。这个结果推广了Viehweg-Zuo和Kebekus-Kovacs的结果。为了证明这一结果,我们表明,任何极端射线的移动锥所产生的一个家庭的曲线,这些曲线收缩后,一定运行的极小模型程序。在log Fano的情况下,这将Araujo的一个定理从klt推广到dlt的情况。为了运行极小模型程序,我们必须切换到X的Q因子分解。由于Q-因子分解通常不是唯一的,我们使用触发器从一个Q-因子分解传递到另一个,证明存在适合我们目的的Q-因子分解。

英文摘要:

Let (X,D) be a dlt pair, where X is a normal projective variety. Let S denote the support of the rounddown of D, and K the canonical divisor of X. We show that any smooth family of canonically polarized varieties over X§is isotrivial if the divisor -(K+D) is ample. This result extends results of Viehweg-Zuo and Kebekus-Kovacs. To prove this result we show that any extremal ray of the moving cone is generated by a family of curves, and these curves are contracted after a certain run of the minimal model program. In the log Fano case, this generalizes a theorem by Araujo from the klt to the dlt case. In order to run the minimal model program, we have to switch to a Q-factorialization of X. As Q-factorializations are generally not unique, we use flops to pass from one Q-factorialization to another, proving the existence of a Q-factorialization suitable for our purposes.

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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