On Wold-type decomposition. (English) Zbl 1254.47021

A new necessary and sufficient condition for a Hilbert space contraction to have \(C_{.0}\) completely nonunitary (cnu) part (in the sense of Sz.-Nagy and Foiaş) is given. This result is used to show that the cnu part of several generalizations of hyponormal contractions is of class \(C_{.0}\).


47B20 Subnormal operators, hyponormal operators, etc.
47A45 Canonical models for contractions and nonselfadjoint linear operators
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