
The authors give a complete list of all genus zero congruence subgroups of \(\text{PSL}_2(\mathbb{Z})\). Up to conjugation, there are 132 of them; they also give the geometric invariants associated to each of these subgroups, as well as independent generators for the subgroups, and generators of the associated function field. The finiteness of the list was a conjecture of Rademacher, which was first resolved in the affirmative by J. Dennin, it can also be deduced from J. Thompson's finiteness theorem. Nonetheless, the complete list given here, (which generalizes the list given by Sebbar for the torsion-free genus zero congruence subgroups), as well as the properties of the groups in the list should prove useful for algebraists and number theorists interested in the congruence subgroups of the modular group.
Unimodular groups, congruence subgroups (group-theoretic aspects), Algebra and Number Theory, Genus, numbers of cusps, Modular group, Subgroup theorems; subgroup growth, modular group, Structure of modular groups and generalizations; arithmetic groups, function fields, 510, genera, Rademacher conjecture, fundamental polygons, congruence subgroups, Hauptmodul, indices, Farey symbols, Congruence subgroups, generators
Unimodular groups, congruence subgroups (group-theoretic aspects), Algebra and Number Theory, Genus, numbers of cusps, Modular group, Subgroup theorems; subgroup growth, modular group, Structure of modular groups and generalizations; arithmetic groups, function fields, 510, genera, Rademacher conjecture, fundamental polygons, congruence subgroups, Hauptmodul, indices, Farey symbols, Congruence subgroups, generators
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 8 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
