## 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 $$C_{.0}$$.

### MSC:

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

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