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18th International Conference on Operator Theory
June 27 - July 1, 2000
University of the West
Timisoara, Romania

Organizers
Dumitru Gaspar, Traian Ceausu, Aurelian Craciunescu, Aurelian Gheondea, Radu-Nicolae Gologan, Ciprian Pop, Dan Popovici, Nicolae Suciu, Alexandru Terescenco, Dan Timotin, Flavius Turcu

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From standard to non-standard perturbations of contractions
by
Chafiq Benhida
Universite de Lille 1
Coauthors: Dan Timotin

Let T be a contraction on a Hilbert space H, with finite defect indices m, m+k and such that T is C., 0 (T*nx --> 0 for every x in H). We study contractive finite dimensional perturbations of T and prove that the completely nonunitary part of such a perturbation is also C., 0, while the unitary part is singular. When the defect indices of T are not equal, we show that T is unitarily equivalent to a finite rank perturbation of dimension m of the k-dimensional shift.

Date received: June 15, 2000

Copyright © 2000 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caeo-68.