Threefolds whose canonical bundles are not numerically effective.
Threefolds whose canonical bundles are not numerically effective.
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DOI：
10.1073/pnas.77.6.3125
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发表时间：
1980-06
影响因子：
11.1
通讯作者：
S. Mori
中科院分区：
文献类型：
--
作者：
S. Mori
设X是三重非奇异射影，其标准丛在数值上是不有效的。然后我们得到：(I)X包含几种类型的例外因子，我们对它进行了显式分类，(Ii)X具有到其纤维为二次曲线的射影非奇异曲面的态射，(Iii)X具有到其一般纤维为Del Pezzo曲面的射影非奇异曲线的态射，或(Iv)X是Picard数为1的Fano三重曲面。
Let X be an arbitrary nonsingular projective 3-fold whose canonical bundle is not numerically effective. Then we have: (i) X contains an exceptional divisor of several types, which we classify explicitly, (ii) X has a morphism to a projective nonsingular surface whose fibers are conics, (iii) X has a morphism to a projective nonsingular curve whose general fibers are Del Pezzo surfaces, or (iv) X is a Fano 3-fold with Picard number 1.