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arXiv · 1806.02668

Unramified Brauer groups of conic bundle threefolds in characteristic two

Asher Auel·Alessandro Bigazzi·Christian Böhning·Hans-Christian Graf von Bothmer
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Abstract

We establish a formula for computing the unramified Brauer group of tame conic bundle threefolds in characteristic 2. The formula depends on the arrangement and residue double covers of the discriminant components, the latter being governed by Artin-Schreier theory (instead of Kummer theory in characteristic not 2). We use this to give new examples of threefold conic bundles defined over the integers that are not stably rational over the complex numbers.

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Asher Auel, Alessandro Bigazzi, Christian Böhning, Hans-Christian Graf von Bothmer. 2018-06-07. Unramified Brauer groups of conic bundle threefolds in characteristic two. https://arxiv.org/abs/1806.02668

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