3.II .7E. 7 \mathrm{E} \quad

Groups
Part IA, 2008

Show that every Möbius map may be expressed as a composition of maps of the form zz+a,zλzz \mapsto z+a, z \mapsto \lambda z and z1/zz \mapsto 1 / z (where aa and λ\lambda are complex numbers).

Which of the following statements are true and which are false? Justify your answers.

(i) Every Möbius map that fixes \infty may be expressed as a composition of maps of the form zz+az \mapsto z+a and zλzz \mapsto \lambda z (where aa and λ\lambda are complex numbers).

(ii) Every Möbius map that fixes 0 may be expressed as a composition of maps of the form zλzz \mapsto \lambda z and z1/zz \mapsto 1 / z (where λ\lambda is a complex number).

(iii) Every Möbius map may be expressed as a composition of maps of the form zz+az \mapsto z+a and z1/zz \mapsto 1 / z (where aa is a complex number).