Odd quadratic orders and real $j$-invariants

Fuente: arXiv
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1. Verfasser: Zarhin, Yuri G.
Format: Preprint
Veröffentlicht: 2024
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author Zarhin, Yuri G.
author_facet Zarhin, Yuri G.
contents Let $O$ be an order of odd discriminant $D$ in an imaginary quadratic field $K$. Let $Cl(O)$ be the group of proper $O$-ideals and $Cl(O)[2]$ the kernel of multiplication by $2$ in $Cl(O)$. We describe explicitly the group $Cl(O)[2]$. In particular, we prove that its order is $2^{s_D-1}$ where $s_D$ is the number of prime divisors of $D$.
format Preprint
id arxiv_https___arxiv_org_abs_2407_16703
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Odd quadratic orders and real $j$-invariants
Zarhin, Yuri G.
Number Theory
Algebraic Geometry
11R11, 11R29, 11R65, 11G15, 14H52
Let $O$ be an order of odd discriminant $D$ in an imaginary quadratic field $K$. Let $Cl(O)$ be the group of proper $O$-ideals and $Cl(O)[2]$ the kernel of multiplication by $2$ in $Cl(O)$. We describe explicitly the group $Cl(O)[2]$. In particular, we prove that its order is $2^{s_D-1}$ where $s_D$ is the number of prime divisors of $D$.
title Odd quadratic orders and real $j$-invariants
topic Number Theory
Algebraic Geometry
11R11, 11R29, 11R65, 11G15, 14H52
url https://arxiv.org/abs/2407.16703