Additive combinations of special operators

Wu, Pei

Banach Center Publications, Tome 29 (1994), p. 337-361 / Harvested from The Polish Digital Mathematics Library

Résumé

This is a survey paper on additive combinations of certain special-type operators on a Hilbert space. We consider (finite) linear combinations, sums, convex combinations and/or averages of operators from the classes of diagonal operators, unitary operators, isometries, projections, symmetries, idempotents, square-zero operators, nilpotent operators, quasinilpotent operators, involutions, commutators, self-commutators, norm-attaining operators, numerical-radius-attaining operators, irreducible operators and cyclic operators. In each case, we are mainly concerned with the characterization of such combinations and the minimal number of the special operators required in them. We will omit the proofs of most of the results here but give some indication or brief sketch of the ideas behind and point out the remaining open problems.

Détail

Publié le : 1994-01-01

Zbl 0814.47001

EUDML-ID : urn:eudml:doc:262750

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