arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1801.04784math.AGmath.RT
收藏

奇异曲线- II上主丛的平凡性

Triviality properties of principal bundles on singular curves-II

Prakash Belkale, Najmuddin Fakhruddin

摘要:

对于$G$是分裂半单群概型,$P$是相对曲线$X\to S$上的主$G$ -丛,我们研究了$P$在相对充足的Cartier因子$D \subset X$的补上平凡性的一个自然障碍.我们表明,通过构建明确的例子,障碍是非平凡的,如果$G$是不是简单连接,但它可以消失,如果$S$是频谱的DVR(和其他一些假设),由一个忠实的平基地的变化。如果$S$是光滑曲线,且$X-D$的奇异轨迹在$S$上是有限的,则此障碍的消失是etale局部平凡性的充分条件.

英文摘要:

For $G$ a split semi-simple group scheme and $P$ a principal $G$-bundle on a relative curve $X\to S$, we study a natural obstruction for the triviality of $P$ on the complement of a relatively ample Cartier divisor $D \subset X$. We show, by constructing explicit examples, that the obstruction is nontrivial if $G$ is not simply connected but it can be made to vanish, if $S$ is the spectrum of a dvr (and some other hypotheses), by a faithfully flat base change. The vanishing of this obstruction is shown to be a sufficient condition for etale local triviality if $S$ is a smooth curve, and the singular locus of $X-D$ is finite over $S$.

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。

↑