New posts in Modular Group

Does every subgroup of finite index contain a power of each element of the group?

Subgroups of $SL_2(\mathbb R)$ which contain $SL_2(\mathbb Z)$ as a finite index subgroup

Enumerating cosets of the modular group

Analytic function avoiding elements of the modular group

Congruence Subgroups as Open Subgroups of the Modular Group Under the Right Topology