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arXiv · 1112.3089

The Brauer group and the Brauer-Manin set of products of varieties

Alexei N. Skorobogatov·Yuri G. Zarhin
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Abstract

Let $X$ and $Y$ be smooth and projective varieties over a field $k$ finitely generated over $\mathbb Q$, and let $\ov X$ and $\ov Y$ be the varieties over an algebraic closure of $k$ obtained from $X$ and $Y$, respectively, by extension of the ground field. We show that the Galois invariant subgroup of $\Br(\ov X)\oplus \Br(\ov Y)$ has finite index in the Galois invariant subgroup of $\Br(\ov X\times\ov Y)$. This implies that the cokernel of the natural map $\Br(X)\oplus\Br(Y)\to\Br(X\times Y)$ is finite when $k$ is a number field. In this case we prove that the Brauer-Manin set of the product of varieties is the product of their Brauer-Manin sets.

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Alexei N. Skorobogatov, Yuri G. Zarhin. 2011-12-14. The Brauer group and the Brauer-Manin set of products of varieties. https://arxiv.org/abs/1112.3089

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