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arXiv 1001.4574math.AGmath.ATmath.KT
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双有理不变量与A^1-连通性

Birational invariants and A^1-connectedness

Aravind Asok

摘要:

本文研究了A^1-同伦理论与双有理几何之间关系的某些方面。研究了域k上光滑代数簇的A^1-奇异链复形和第零A^1-同调层。我们展示了一些方式,这些对象是类似于他们的同行在经典拓扑结构和类似的motivic同行(Voevodsky)动机和零Suslin同调层)。我们证明,如果k是无限的第零A^1-同调层是光滑真簇的双有理不变量,我们解释了这些层如何控制各种上同调不变量,例如,非分歧平展上同调。特别地,我们推导出了A^1-连通簇的上同调的一些消失结果。最后,我们给出了这些消没命题的部分逆命题,通过非分歧不变量的消没给出了A^1-连通性的一个刻画。

英文摘要:

We study some aspects of the relationship between A^1-homotopy theory and birational geometry. We study the so-called A^1-singular chain complex and zeroth A^1-homology sheaf of smooth algebraic varieties over a field k. We exhibit some ways in which these objects are similar to their counterparts in classical topology and similar to their motivic counterparts (the (Voevodsky) motive and zeroth Suslin homology sheaf). We show that if k is infinite the zeroth A^1-homology sheaf is a birational invariant of smooth proper varieties, and we explain how these sheaves control various cohomological invariants, e.g., unramified étale cohomology. In particular, we deduce a number of vanishing results for cohomology of A^1-connected varieties. Finally, we give a partial converse to these vanishing statements by giving a characterization of A^1-connectedness by means of vanishing of unramified invariants.

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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