Extended hecke groups h lambda q and their fundamental regions

Abstract

We consider the extended Hecke groups H( q) generated by T(z) = 1= z, S(z) = 1=(z + q) and R(z) = 1=z with q = 2 cos( =q) for q 3 an integer: In this work, we give abstract group structure and fundamental region of the extended Hecke groups H( q