Identifying normal and congruence subgroups

TL;DR

This paper introduces a straightforward algorithm to identify whether a finite index subgroup of the Hecke group is normal, aiding in the analysis of subgroup structures within these mathematical groups.

Contribution

The paper presents a novel, simple algorithm specifically designed for determining normality of finite index subgroups in Hecke groups.

Findings

Algorithm effectively determines normal subgroups

Simplifies subgroup analysis in Hecke groups

Potential applications in group theory research

Abstract

We give a simple algorithm that enables us to determine whether a subgroup of finite index of the Hecke group is normal.