Pro-$\ell$-by-cyclotomic and tamely ramified variants of the Neukirch-Uchida Theorem

Fuente: arXiv
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Main Authors: Karshon, Ido, Shusterman, Mark
Format: Preprint
Published: 2026
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author Karshon, Ido
Shusterman, Mark
author_facet Karshon, Ido
Shusterman, Mark
contents We prove a generalization of the Neukirch-Uchida Theorem. In particular, we show that the isomorphism type of a number field $K$ can be recovered from the maximal pro-$\ell$-by-cyclotomic quotient of its absolute Galois group $G_{\overline{K}/K}$. This should be contrasted with the previous result that the isomorphism type cannot, in general, be recovered from the maximal pronilpotent quotient. We also show that the isomorphism type can be recovered from the maximal tamely ramified quotient.
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id arxiv_https___arxiv_org_abs_2601_01251
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pro-$\ell$-by-cyclotomic and tamely ramified variants of the Neukirch-Uchida Theorem
Karshon, Ido
Shusterman, Mark
Number Theory
12G05, 11S20, 11S25, 11R32, 11R34, 11R37, 11R42, 16K50, 20E18
We prove a generalization of the Neukirch-Uchida Theorem. In particular, we show that the isomorphism type of a number field $K$ can be recovered from the maximal pro-$\ell$-by-cyclotomic quotient of its absolute Galois group $G_{\overline{K}/K}$. This should be contrasted with the previous result that the isomorphism type cannot, in general, be recovered from the maximal pronilpotent quotient. We also show that the isomorphism type can be recovered from the maximal tamely ramified quotient.
title Pro-$\ell$-by-cyclotomic and tamely ramified variants of the Neukirch-Uchida Theorem
topic Number Theory
12G05, 11S20, 11S25, 11R32, 11R34, 11R37, 11R42, 16K50, 20E18
url https://arxiv.org/abs/2601.01251