Definable sets of Berkovich curves
Abstract
In this article, we functorially associate definable sets to -analytic curves, and definable maps to analytic morphisms between them, for a large class of -analytic curves. Given a -analytic curve , our association allows us to have definable versions of several usual notions of Berkovich analytic geometry such as the branch emanating from a point and the residue curve at a point of type 2. We also characterize the definable subsets of the definable counterpart of and show that they satisfy a bijective relation with the radial subsets of . As an application, we recover (and slightly extend) results of Temkin concerning the radiality of the set of points with a given prescribed multiplicity with respect to a morphism of -analytic curves. In the case of the analytification of an algebraic curve, our construction can also be seen as an explicit version of Hrushovski and Loeser's theorem on iso-definability of curves. However, our approach can also be applied to strictly -affinoid curves and arbitrary morphisms between them, which are currently not in the scope of their setting.
Keywords
Cite
@article{arxiv.1809.07156,
title = {Definable sets of Berkovich curves},
author = {Pablo Cubides Kovacsics and Jérôme Poineau},
journal= {arXiv preprint arXiv:1809.07156},
year = {2023}
}
Comments
53 pages, 1 figure. v2: Section 7.2 on weakly stable fields added and other minor changes. Final version. To appear in Journal of the Institute of Mathematics of Jussieu