Presentations of Galois groups of unramified extensions of global fields and its predicted distribution

Fuente: arXiv
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Auteur principal: Willyard, Ken
Format: Preprint
Publié: 2026
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author Willyard, Ken
author_facet Willyard, Ken
contents Motivated by the work of Liu, we study certain canonical quotients of $G_{\emptyset}^T(K)$ -- the Galois group of the maximal unramified extension of a global field $K$ that is split completely at a finite nonempty set of places in $T$ -- for $Γ$-extensions $K/Q$, and prove they have presentations of a particular form. This presentation leads us to the construction of a new random group model as in the work of Liu, Wood, and Zureick-Brown that predicts the distribution of $G_{\emptyset}^T(K)$ as we vary among $Γ$-extensions $K/Q$ with prescribed local conditions at places in $T$, giving a generalization of the non-abelian Cohen-Lenstra-Martinet Heuristics. The key generalization is that $Q$ can be an arbitrary global field, while this comes at a cost of introducing a prime-to-$|\text{Cl}_T(Q)|$ condition in addition to avoiding roots of unity, $|Γ|$, and the characteristic if $Q$ is a function field.
format Preprint
id arxiv_https___arxiv_org_abs_2605_14158
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Presentations of Galois groups of unramified extensions of global fields and its predicted distribution
Willyard, Ken
Number Theory
Motivated by the work of Liu, we study certain canonical quotients of $G_{\emptyset}^T(K)$ -- the Galois group of the maximal unramified extension of a global field $K$ that is split completely at a finite nonempty set of places in $T$ -- for $Γ$-extensions $K/Q$, and prove they have presentations of a particular form. This presentation leads us to the construction of a new random group model as in the work of Liu, Wood, and Zureick-Brown that predicts the distribution of $G_{\emptyset}^T(K)$ as we vary among $Γ$-extensions $K/Q$ with prescribed local conditions at places in $T$, giving a generalization of the non-abelian Cohen-Lenstra-Martinet Heuristics. The key generalization is that $Q$ can be an arbitrary global field, while this comes at a cost of introducing a prime-to-$|\text{Cl}_T(Q)|$ condition in addition to avoiding roots of unity, $|Γ|$, and the characteristic if $Q$ is a function field.
title Presentations of Galois groups of unramified extensions of global fields and its predicted distribution
topic Number Theory
url https://arxiv.org/abs/2605.14158