Note on M groups

Abstract

A compact Klein surface with boundary of algebraic genus g≥ 2 has at most 12(91) automorphisms. When a surface attains this bound, it has maximal sym-metry, and the group of automorphisms is then called an M-group. In this paper, we consider the extended modular group I and we give some new examples of M*-groups which are finite quotient groups of F.