Recent Progress in Operator Theory: International Workshop on Operator Theory and Applications, IWOTA 95, in Regensburg, July 31–August 4,1995 (Operator Theory: Advances and Applications, 103)

This and the previous volume of the OT series contain the proceedings of the Workshop on Operator Theory and its Applications, IWOTA 95, which was held at the University of Regensburg, Germany, July 31 to August 4, 1995. It was the eigth workshop of this kind. Following is a list of the seven previous workshops with reference to their proceedings: 1981 Operator Theory (Santa Monica, California, USA) 1983 Applications of Linear Operator Theory to Systems and Networks (Rehovot, Israel), OT 12 1985 Operator Theory and its Applications (Amsterdam, The Netherlands), OT 19 1987 Operator Theory and Functional Analysis (Mesa, Arizona, USA), OT 35 1989 Matrix and Operator Theory (Rotterdam, The Netherlands), OT 50 1991 Operator Theory and Complex Analysis (Sapporo, Japan), OT 59 1993 Operator Theory and Boundary Eigenvalue Problems (Vienna, Austria), OT 80 IWOTA 95 offered a rich programme on a wide range of latest developments in operator theory and its applications. The programme consisted of 6 invited plenary lectures, 54 invited special topic lectures and more than 100 invited session talks. About 180 participants from 25 countries attended the workshop, more than a third came from Eastern Europe. The conference covered different aspects of linear and nonlinear spectral prob­ lems, starting with problems for abstract operators up to spectral theory of ordi­ nary and partial differential operators, pseudodifferential operators, and integral operators. The workshop was also focussed on operator theory in spaces with indefinite metric, operator functions, interpolation and extension problems. Front Matter....Pages I-XIII Inversion Formulas for Compressions of block-Toeplitz Operators....Pages 1-17 Contractive linear relations in Pontryagin spaces....Pages 19-51 On a new algorithm for almost periodic factorization....Pages 53-74 On the normal solvability of cohomological equations on compact topological spaces....Pages 75-87 On nonnegative realizations of rational matrix functions and nonnegative input-output systems....Pages 89-104 On the geometric structure of regular dilations....Pages 105-120 On generalized interpolation and shift invariant maximal semidefinite subspaces....Pages 121-136 The sum of matrix nevanlinna functions and self-adjoint extensions in exit spaces....Pages 137-154 Properties of “derived” Hankel matrices....Pages 155-170 The Probability that a (partial) matrix is positive semidefinite....Pages 171-182 Factorization of lower triangular unitary operators with finite kronecker index into elementary factors....Pages 183-217 Fredholm theory of interpolation morphisms....Pages 219-231 Resolvents of symmetric sperators and the degenerated Nevanlinna-Pick problem....Pages 233-261 Perturbation of linear semigroups....Pages 263-277 On the approximation of operators and the convergence of the spectra of the approximants....Pages 279-283 Back Matter....Pages 284-285 The Workshop on Operator Theory and Its Applications, IWOTA 95, was held at the University of Regensburg, Germany, July 31 to August 4, 1995. It was the eighth workshop in the series of IWOTA (International Workshops on Operator Theory and Applications). The conference covered different aspects of linear and nonlinear spectral problems, starting with problems for abstract operators up to spectral theory of ordinary and partial operators, pseudodifferential operators, and integral operators. The workshop was also focussed on operator theory in spaces with indefinite metric, operator functions, interpolation and extension problems. The applications concerned applications to mathematical physics, hydrodynamics, magnetohydrodynamics, quantum mechanics, astrophysics as well as the theory of networks and systems. The papers in the two volumes of the proceedings of IWOTA 95 bring the readers up to date on recent achievements in these areas. This volume contains the contributions to different aspects of operator theory and its applications. Its companion volume (OT 102) is focussed especially on differential and integral operators. The set will be of practical use to a wide-range readership in pure and applied mathematics, physics and engineering sciences. This Volume Brings Readers Up To Date On Different Aspects Of Operator Theory And Its Applications, Including Mathematical Physics, Hydrodynamics, Magnetohydrodynamics, Quantum Mechanics, Astrophysics As Well As The Theory Of Networks And Systems. Of Practical Use To A Wide Readership In Pure And Applied Mathematics, Physics And Engineering Sciences.