Linear Operators and Matrices The Peter Lancaster Anniversary Volume

In September 1998, during the 'International Workshop on Analysis and Vibrat­ ing Systems' held in Canmore, Alberta, Canada, it was decided by a group of participants to honour Peter Lancaster on the occasion of his 70th birthday with a volume in the series 'Operator Theory: Advances and Applications'. Friends and colleagues responded enthusiastically to this proposal and within a short time we put together the volume which is now presented to the reader. Regarding accep­ tance of papers we followed the usual rules of the journal 'Integral Equations and Operator Theory'. The papers are dedicated to different problems in matrix and operator theory, especially to the areas in which Peter contributed so richly. At our request, Peter agreed to write an autobiographical paper, which appears at the beginning of the volume. It continues with the list of Peter's publications. We believe that this volume will pay tribute to Peter on his outstanding achievements in different areas of mathematics. 1. Gohberg, H. Langer P ter Lancast r *1929 Operator Theory: Advances and Applications, Vol. 130, 1- 7 © 2001 Birkhiiuser Verlag Basel/Switzerland My Life and Mathematics Peter Lancaster I was born in Appleby, a small county town in the north of England, on November 14th, 1929. I had two older brothers and was to have one younger sister. My family moved around the north of England as my father's work in an insurance company required.

My Life and Mathematics.- List of Publications of Peter Lancaster.- Forty-four Years with Peter Lancaster.- Peter Lancaster, my Friend and Co-author.- The Joint Numerical Range of Bordered and Tridiagonal Matrices.- Iterative Computation of Higher Derivatives of Repeated Eigenvalues and the Corresponding Eigenvectors.- Colligations in Pontryagin Spaces with a Symmetric Characteristic Function.- Logarithmic Residues of Fredholm Operator Valued Functions and Sums of Finite Rank Projections.- Positive Linear Maps and the Lyapunov Equation.- Full-and Partial-Range Completeness.- Spectral Isomorphisms between Generalized Sturm-Liouville Problems.- Existence and Uniqueness Results for Nonlinear Cooperative Systems.- Young’s Inequality in Compact Operators.- Partial Indices of Small Perturbations of a Degenerate Continuous Matrix Function.- Finite Section Method for Difference Equations.- Iterative Solution of a Matrix Riccati Equation Arising in Stochastic Control.- Lyapunov Functions and Solutions of the Lyapunov Matrix Equation for Marginally Stable Systems.- Invariant Subspaces of Infinite Dimensional Hamiltonians and Solutions of the Corresponding Riccati Equations.- Inertia Bounds for Operator Polynomials.- A Note on the Level Sets of a Matrix Polynomial and its Numerical Range.