Indefinite Inner Product Spaces Schur Analysis and Differential Equations : A Volume Dedicated to Heinz Langer 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.