Genus theory, governing field, ramification and Frobenius

Fuente: arXiv
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Autori principali: Mfumu, Roslan Ibara Ngiza, Maire, Christian
Natura: Preprint
Pubblicazione: 2024
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author Mfumu, Roslan Ibara Ngiza
Maire, Christian
author_facet Mfumu, Roslan Ibara Ngiza
Maire, Christian
contents In this work we develop, through a governing field, genus theory for a number field $\K$ with tame ramification in $T$ and splitting in $S$, where $T$ and $S$ are finite disjoint sets of primes of $\K$. This approach extends that initiated by the second author in the case of the class group. It allows expressing the $S$-$T$ genus number of a cyclic extension $Ł/\K$ of degree $p$ in terms of the rank of a matrix constructed from the Frobenius elements of the primes ramified in $Ł/\K$, in the Galois group of the underlying governing extension. For quadratic extensions $Ł/\Q$, the matrices in question are constructed from the Legendre symbols between the primes ramified in $Ł/\Q$ and the primes in $S$.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03754
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Genus theory, governing field, ramification and Frobenius
Mfumu, Roslan Ibara Ngiza
Maire, Christian
Number Theory
In this work we develop, through a governing field, genus theory for a number field $\K$ with tame ramification in $T$ and splitting in $S$, where $T$ and $S$ are finite disjoint sets of primes of $\K$. This approach extends that initiated by the second author in the case of the class group. It allows expressing the $S$-$T$ genus number of a cyclic extension $Ł/\K$ of degree $p$ in terms of the rank of a matrix constructed from the Frobenius elements of the primes ramified in $Ł/\K$, in the Galois group of the underlying governing extension. For quadratic extensions $Ł/\Q$, the matrices in question are constructed from the Legendre symbols between the primes ramified in $Ł/\Q$ and the primes in $S$.
title Genus theory, governing field, ramification and Frobenius
topic Number Theory
url https://arxiv.org/abs/2407.03754