Parametrization and Schur algorithm for the integral representation of Hankel forms in T-square
Potapov-Ginsburg Transformation and Functional Models of Non-Dissipative Operators
2000 Mathematics Subject Classification: Primary 47A20, 47A45; Secondary 47A48.A relation between an arbitrary bounded operator A and dissipative operator A+, built by A in the following way A+ = A+ij*Q-j, where A-A* = ij*Jj, (J = Q+-Q- is involution), is studied. The characteristic functions of the operators A and A+ are expressed by each other using the known Potapov-Ginsburg linear-fractional transformations. The explicit form of the resolvent (A-lI)-1 is expressed by (A+-lI)-1 and (A+*-lI)-1...
Projections, extendability of operators and the Gâteaux derivative of the norm.
Projectivity and lifting of Hilbert module maps
In a recent paper, Carlson, Foiaş, Williams and the author proved that isometric Hilbert modules are projective in the category of Hilbert modules similar to contractive ones. In this paper, a simple proof, based on a strengthened lifting theorem, is given. The proof also applies to an equivalent theorem of Foiaş and Williams on similarity to a contraction of a certain 2 × 2 operator matrix.
Prolongement d’un opérateur d’un sous-espace de dans
Propriétés analytiques des valeurs et vecteurs propres des opérateurs de l'espace de Hilbert