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arXiv · 1709.03094

On the local behaviour of specializations of function field extensions

Joachim König·François Legrand·Danny Neftin
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Abstract

Given a field $k$ of characteristic zero and an indeterminate $T$ over $k$, we investigate the local behaviour at primes of $k$ of finite Galois extensions of $k$ arising as specializations of finite Galois extensions $E/k(T)$ (with $E/k$ regular) at points $t_0 \in \mathbb{P}^1(k)$. We provide a general result about decomposition groups at primes of $k$ in specializations, extending a fundamental result of Beckmann concerning inertia groups. We then apply our result to study crossed products, the Hilbert--Grunwald property, and finite parametric sets.

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Joachim König, François Legrand, Danny Neftin. 2018-01-05. On the local behaviour of specializations of function field extensions. https://arxiv.org/abs/1709.03094

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