Brendan Creutz ; Jose Felipe Voloch - Etale descent obstruction and anabelian geometry of curves over finite fields

epiga:11483 - Épijournal de Géométrie Algébrique, July 9, 2024, Volume 8 - https://doi.org/10.46298/epiga.2024.11483
Etale descent obstruction and anabelian geometry of curves over finite fieldsArticle

Authors: Brendan Creutz ; Jose Felipe Voloch

    Let $C$ and $D$ be smooth, proper and geometrically integral curves over a finite field $F$. Any morphism from $D$ to $C$ induces a morphism of their étale fundamental groups. The anabelian philosophy proposed by Grothendieck suggests that, when $C$ has genus at least $2$, all open homomorphisms between the étale fundamental groups should arise in this way from a nonconstant morphism of curves. We relate this expectation to the arithmetic of the curve $C_K$ over the global function field $K = F(D)$. Specifically, we show that there is a bijection between the set of conjugacy classes of well-behaved morphism of fundamental groups and locally constant adelic points of $C_K$ that survive étale descent. We use this to provide further evidence for the anabelian conjecture by relating it to another recent conjecture by Sutherland and the second author.


    Volume: Volume 8
    Published on: July 9, 2024
    Accepted on: February 16, 2024
    Submitted on: June 20, 2023
    Keywords: Mathematics - Number Theory,Mathematics - Algebraic Geometry,11G20, 11G30, 14G05, 14G15

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