The image of the generalized Dedekind sum

Fuente: arXiv
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Main Authors: Knight, Evelyne S., Matos, Carlos Alexov, Sefidi, Amira, Young, Matthew P.
Format: Preprint
Published: 2025
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author Knight, Evelyne S.
Matos, Carlos Alexov
Sefidi, Amira
Young, Matthew P.
author_facet Knight, Evelyne S.
Matos, Carlos Alexov
Sefidi, Amira
Young, Matthew P.
contents The newform Dedekind sum $S_{χ_1, χ_2}$ associated to a pair of primitive Dirichlet characters $χ_1$, $χ_2$ of respective conductors $q_1$, $q_2$, is a group homomorphism from $Γ_1(q_1 q_2)$ into the number field $F_{χ_1, χ_2}$ generated by the values of the characters. It is a basic question to identify the image of this map, which is known to be a lattice $L_{χ_1, χ_2}$ in $F_{χ_1, χ_2}$. It has recently been conjectured that when $χ_1$ and $χ_2$ are quadratic, then $ L_{χ_1, χ_2} = 2 \mathbb{Z}$. In this paper, we make some progress towards this conjecture by exhibiting an explicit lattice in which $L_{χ_1, χ_2}$ is contained; in particular, when the characters are quadratic, the $q_i$ are coprime, odd, and sufficiently large, then $L_{χ_1, χ_2} \subseteq \mathbb{Z}$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_09741
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The image of the generalized Dedekind sum
Knight, Evelyne S.
Matos, Carlos Alexov
Sefidi, Amira
Young, Matthew P.
Number Theory
The newform Dedekind sum $S_{χ_1, χ_2}$ associated to a pair of primitive Dirichlet characters $χ_1$, $χ_2$ of respective conductors $q_1$, $q_2$, is a group homomorphism from $Γ_1(q_1 q_2)$ into the number field $F_{χ_1, χ_2}$ generated by the values of the characters. It is a basic question to identify the image of this map, which is known to be a lattice $L_{χ_1, χ_2}$ in $F_{χ_1, χ_2}$. It has recently been conjectured that when $χ_1$ and $χ_2$ are quadratic, then $ L_{χ_1, χ_2} = 2 \mathbb{Z}$. In this paper, we make some progress towards this conjecture by exhibiting an explicit lattice in which $L_{χ_1, χ_2}$ is contained; in particular, when the characters are quadratic, the $q_i$ are coprime, odd, and sufficiently large, then $L_{χ_1, χ_2} \subseteq \mathbb{Z}$.
title The image of the generalized Dedekind sum
topic Number Theory
url https://arxiv.org/abs/2503.09741