Sparseness of Exceptional Quotient Singularities
Sparseness of Exceptional Quotient Singularities
复制标题
异常商奇点的稀疏性
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Yuri Prokhorov
中科院分区：
文献类型：
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作者：
Yuri Prokhorov
定义1.1(见[3，5.6])。设(X，P)是正规奇点，D=∑Didi是X上的有效q因子，使得(X，D)对仅有对数标准奇点。如果函数域K(X)至多有一个因子E且偏差a(E，D)=−1，则称(X，D)对为例外。如果(X，D)对(X，D)是例外的，则称(X，D)为例外对。
Definition 1.1 (see [3, 5.6]). Let (X P ) be a normal singularity and let D = ∑ diDi be an effective Q -divisor on X such that the pair (X, D) has log-canonical singularities only. A pair (X, D) is said to be exceptional if there is at most one divisor E of the function field K(X) with discrepancy a(E, D) = −1. A log-canonical singularity (X P ) is said to be exceptional if a pair (X, D) is exceptional whenever it is log-canonical.