Groups commensurable with the modular group.
type: Item
instance of: scholarly article
title: Groups commensurable with the modular group.
zbMATH Open document ID: 1068.20050
DOI: 10.1016/S0021-8693(03)00421-6
published in: Journal of Algebra
publication date: 2004-10-01T00:00:00Z
review text: The author studies the groups commensurable with the well known modular group. It is known that the only Hecke groups commensurable with the modular group are those for \(q=3,4\) and 6. Here the author takes two maximal subgroups \(A\) and \(B\) of the group of isomorphisms of the upper half plane which are commensurable with the modular group, and then determines the index and also the level of the intersection of \(A\) and \(B\) in \(A\). If the index is finite, then the group is classified as commensurable with the modular group.
Mathematics Subject Classification ID: 20H05
Mathematics Subject Classification ID: 20E07
Mathematics Subject Classification ID: 20E28
zbMATH DE Number: 2105375
zbMATH Keywords: modular group
zbMATH Keywords: commensurability
zbMATH Keywords: Hecke groups
zbMATH Keywords: maximal subgroups
zbMATH Keywords: subgroups of finite index
author: Mong Lung Lang
reviewed by: Ismail Naci Cangül
MaRDI profile type: Publication
cites work: Hecke operators on \(\Gamma_0(m)\)
cites work: The normalizer of Γ0(N) in PSL(2, ℝ)
cites work: Q3927897
cites work: Q4878693
cites work: Bestimmung der Kommensurabilitätsklasse der Hilbertschen Modulgruppe
cites work: Normalisers of subgroups of the modular group
cites work: Arithmétique des algèbres de quaternions
description: scientific article; zbMATH DE number 2105375