Contributions to Operator Theory in Spaces with an Indefinite Metric: The Heinz Langer Anniversary Volume

Front Matter....Pages i-vii
Heinz Langer and his work....Pages 1-22
On the spectra of some classes of quadratic operator pencils....Pages 23-36
Special realizations for Schur upper triangular operators....Pages 37-90
On the defect of noncontractive operators in Kreĭn spaces: a new formula and some applications....Pages 91-112
Positive differential operators in the Krein space L 2 (ℝ n )....Pages 113-129
Singular values of positive pencils and applications....Pages 131-146
Perturbations of Krein spaces preserving the nonsingularity of the critical point infinity....Pages 147-155
An analysis of the block structure of j qq -inner functions....Pages 157-185
Selfadjoint extensions of the orthogonal sum of symmetric relations, II....Pages 187-200
Some interpolation problems of Nevanlinna-Pick type. The Kreĭn-Langer method....Pages 201-216
On the spectral representation for singular selfadjoint boundary eigenvalue problems....Pages 217-251
Some characteristics of a linear manifold in a Kreĭn space and their applications....Pages 253-257
Riggings and relatively form bounded perturbations of nonnegative operators in Kreĭn spaces....Pages 259-273
Norm bounds for Volterra integral operators and time-varying linear systems with finite horizon....Pages 275-290
The numerical range of selfadjoint matrix polynomials....Pages 291-304
Spectral properties of a matrix polynomial connected with a component of its numerical range....Pages 305-308
Lyapunov stability of a perturbed multiplication operator....Pages 309-326
Multiplicative perturbations of positive operators in Krein spaces....Pages 327-336
On the number of negative squares of certain functions....Pages 337-353
Factorization of elliptic pencils and the Mandelstam hypothesis....Pages 355-387
An inductive limit procedure within the quantum harmonic oscillator....Pages 389-395
Canonical systems with a semibounded spectrum....Pages 397-417
Back Matter....Pages 419-421