%0 Journal Article
%T Fundamental domains for congruence subgroups of SL2 in positive characteristic
%A Lisa Carbone
%A Leigh Cobbs
%A Scott H. Murray
%J Mathematics
%D 2009
%I arXiv
%X In this work, we construct fundamental domains for congruence subgroups of $SL_2(F_q[t])$ and $PGL_2(F_q[t])$. Our method uses Gekeler's description of the fundamental domains on the Bruhat- Tits tree $X = X_{q+1}$ in terms of cosets of subgroups. We compute the fundamental domains for a number of congruence subgroups explicitly as graphs of groups using the computer algebra system Magma.
%U http://arxiv.org/abs/0909.0062v2