2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/224618We give an example of an operator that satisfies the curvature condition as defined in [2], but is not similar to the backward shift S* on the Hardy class H^2. We conclude therefore that the contraction assumption in the similarity characterization given in [2] is a necessary requirement.Classical Analysis and ODEs47A99text