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arXiv · 1106.6154

Twisted covers and specializations

Pierre Dèbes·François Legrand
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Abstract

The central topic is this question: is a given $k$-étale algebra $\prod_lE_l/k$ the specialization of a given $k$-cover $f:X\rightarrow B$ at some point $t_0\in B(k)$? Our main tool is a {\it twisting lemma} that reduces the problem to finding $k$-rational points on a certain $k$-variety. Previous forms of this twisting lemma are generalized and unified. New applications are given: a Grunwald form of Hilbert's irreducibility theorem over number fields, a non-Galois variant of the Tchebotarev theorem for function fields over finite fields, some general specialization properties of covers over PAC or ample fields.

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Pierre Dèbes, François Legrand. 2011-06-30. Twisted covers and specializations. https://arxiv.org/abs/1106.6154

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