Refined unramified homology of schemes

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  • Stefan Schreieder

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Original languageEnglish
Publication statusE-pub ahead of print - 12 Oct 2020

Abstract

We introduce refined unramified cohomology groups. This notion allows us to give in arbitrary degree a cohomological interpretation of the failure of integral Hodge- or Tate-type conjectures, of l-adic Griffiths groups, and of the subgroup of the Griffiths group that consists of torsion classes with trivial transcendental Abel--Jacobi invariant. Our approach simplifies and generalizes to cycles of arbitrary codimension previous results of Bloch--Ogus, Colliot-Th\'el\`ene--Voisin, Voisin, and Ma that concerned cycles of low (co-)dimension. As an application, we give for any i>2 the first example of a uniruled smooth complex projective variety for which the integral Hodge conjecture fails for codimension i-cycles in a way that cannot be explained by the failure on any lower-dimensional variety.

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Refined unramified homology of schemes. / Schreieder, Stefan.
2020.

Research output: Working paper/PreprintPreprint

Schreieder, S. (2020). Refined unramified homology of schemes. Advance online publication. https://arxiv.org/abs/2010.05814v4
Schreieder S. Refined unramified homology of schemes. 2020 Oct 12. Epub 2020 Oct 12.
Schreieder, Stefan. / Refined unramified homology of schemes. 2020.
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