Published online by Cambridge University Press: 20 November 2018
Let S be a subnormal operator and let be the weak-star closed algebra generated by S and 1. An example of an irreducible cyclic subnormal operator S is found such that there is a T in
with S and T quasisimilar but not unitarily equivalent. However, if S is the unilateral shift, T ∈
and S and T are quasisimilar, then S ≅ T.