Similarity of an operator to an isometric operator (Q920373)

Conditions in terms of the behaviour of the resolvent are given for an operator T to be similar to an isometry. An additional condition on T is imposed: \(\dim Ker(T^*-\lambda)=1\) for \(\lambda\in D\). The conditions use an analytic function B(\(\lambda\)) such that \((T^*- \lambda)B(\lambda)=0\) for \(\lambda\in D\), B(\(\lambda\)) weakly Nevanlinna.