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北美退伍军人节(Veterans Day),12 日无更新
arXiv 1502.01381math.AG
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典范除子在纯不可分基变换下的行为

Behavior of canonical divisors under purely inseparable base changes

Hiromu Tanaka

摘要:

设$k$是一个不完美域。令$X$是$k$上的正则簇,并将$Y$设置为$(X \times_k k^{1/p^{\infty}})_{\rm red}$的归一化。本文证明了对于$Y$上的某个有效因子$C$,$K_Y+C=f^*K_X$.我们得到以下三个应用。首先,我们证明了具有非正规纤维的$K_X$ -平凡纤维空间是非圆化的。其次,证明了Mori纤维空间的一般纤维是有理链连通的.第三,我们得到了一个弱锥定理的曲面和三重定义在一个不完美的领域。

英文摘要:

Let $k$ be an imperfect field. Let $X$ be a regular variety over $k$ and set $Y$ to be the normalization of $(X \times_k k^{1/p^{\infty}})_{\rm red}$. In this paper, we show that $K_Y+C=f^*K_X$ for some effective divisor $C$ on $Y$. We obtain the following three applications. First, we show that a $K_X$-trivial fiber space with non-normal fibers is uniruled. Second, we prove that general fibers of Mori fiber spaces are rationally chain connected. Third, we obtain a weakening of the cone theorem for surfaces and threefolds defined over an imperfect field.

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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