Continuity of the spectrum of norm-normal matrices
Hyperinvariant subspace lattice of isometries
Hyperinvariant subspace lattice of weak contractions
Hyperinvariant subspace lattice of some -contractions
On reflexivity and hyperreflexivity of some spaces of intertwining operators
Let be weak contractions (in the sense of Sz.-Nagy and Foiaş), the minimal functions of their parts and let be the greatest common inner divisor of . It is proved that the space of all operators intertwining is reflexive if and only if the model operator is reflexive. Here means the compression of the unilateral shift onto the space . In particular, in finite-dimensional spaces the space is reflexive if and only if all roots of the greatest common divisor of minimal polynomials...
Hyperinvariant subspaces of operators on Hilbert spaces
Hyperreflexive operators on finite dimensional Hilbert spaces
In this paper a complete characterization of hyperreflexive operators on finite dimensional Hilbert spaces is given.
Cryptographic techniques used to provide integrity of digital content in long-term storage
The main objective of the project was to obtain advanced mathematical methods to guarantee the verification that a required level of data integrity is maintained in long-term storage. The secondary objective was to provide methods for the evaluation of data loss and recovery. Additionally, we have provided the following initial constraints for the problem: a limitation of additional storage space, a minimal threshold for desired level of data integrity and a defined probability of a single-bit corruption....
Non-hyperreflexive reflexive spaces of operators
We study operators whose commutant is reflexive but not hyperreflexive. We construct a C₀ contraction and a Jordan block operator associated with a Blaschke product B which have the above mentioned property. A sufficient condition for hyperreflexivity of is given. Some other results related to hyperreflexivity of spaces of operators that could be interesting in themselves are proved.
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