This volume which is dedicated to Heinz Langer includes biographical material and carefully
selected papers. Heinz Langer has made fundamental contributions to operator theory. In
particular he has studied the domains of operator pencils and nonlinear eigenvalue problems
the theory of indefinite inner product spaces operator theory in Pontryagin and Krein spaces
and applications to mathematical physics. His works include studies on and applications of
Schur analysis in the indefinite setting where the factorization theorems put forward by Krein
and Langer for generalized Schur functions and by Dijksma-Langer-Luger-Shondin play a key
role. The contributions in this volume reflect Heinz Langer's chief research interests and will
appeal to a broad readership whose work involves operator theory.
