论文标题
与中心计算分区收缩
Counting divisorial contractions with centre a $cA_n$-singularity
论文作者
论文摘要
首先，我们简化了与中心的三维分区收缩的kawakita和Yamamoto有关的现有分类。接下来，我们描述与给定的局部分析等效类别的分区收缩类别与中心A点相对应的全球代数分区收缩。最后，我们将差异的分区收缩至少为固定品种，并带有$ ca_n $ singularity。我们表明，如果存在一种这样的分区收缩，那么存在许多这样的分区收缩。
First, we simplify the existing classification due to Kawakita and Yamamoto of 3-dimensional divisorial contractions with centre a $cA_n$-singularity, also called compound $A_n$ singularity. Next, we describe the global algebraic divisorial contractions corresponding to a given local analytic equivalence class of divisorial contractions with centre a point. Finally, we consider divisorial contractions of discrepancy at least 2 to a fixed variety with centre a $cA_n$-singularity. We show that if there exists one such divisorial contraction, then there exist uncountably many such divisorial contractions.
