Automorphisms of punctured half upper plane

29 Views Asked by At

We know the form of automorphisms of the upper half plane. But I'm asked to calculate the set of automorphism of the upper half plane without a point (in this case is without i). I have tried to analyze the isolated singularity when z=i and I've come to the conclusion that it can't be an essential singularity, and if it's an removable singularity it's necessarily f(i)=i But I'm not sure how to proceed if i it's a pole. Any idea?