Complex function theory operator theory Schur analysis and systems theory : a volume in Honor of V.E. Katsnelson Victor comes to Rehovot My Teacher Viktor Emmanuilovich Katsnelson Some impressions of Viktor Emmanuilovich Katsnelson The good fortune of maintaining a long lasting close friendship and scientic collaboration with V. E. Katsnelson A piece of Victor Katsnelsons mathematical biography Interpolation by contractive multipliers between Fock spaces Regular extensions and defect functions of contractive measurable operator valued functions Free homomorphic relations induced by certain free semicircular families Self adjoint extensions of a symmetric linear relation with nite defect: compressions and Straus subspaces On conditions for complete indeterminacy of the matricial Hamburger moment problem On a Blaschke type condition for subharmonic function with two sets of singularities on the boundary Exponential Taylor domination A closer look at the solution of the truncated matricial moment problem On a class of sectorial relations and the associated closed forms Spectral decompositions of selfadjoint relations in Pontryagin spaces and factorizations of generalized Nevanlinna functions Martin functions of Fuchsian groups and character automorphic subspaces of the Hardy space in the upper half plane. This book is dedicated to Victor Emmanuilovich Katsnelson on the occasion of his 75th birthday and celebrates his broad mathematical interests and contributions.Victor Emmanuilovich’s mathematical career has been based mainly at the Kharkov University and the Weizmann Institute. However it also included a one year guest professorship at Leipzig University in 1991 which led to him establishing close research contacts with the Schur analysis group in Leipzig a collaboration that still continues today. Reflecting these three periods in Victor Emmanuilovichs career present and former colleagues have contributed to this book with research inspired by him and presentations on their joint work. Contributions include papers in function theory (Favorov Golinskii Friedland Goldman Yomdin Kheifets Yuditskii) Schur analysis moment problems and related topics (Boiko Dubovoy Dyukarev Fritzsche Kirstein Mädler) extension of linear operators and linear relations (Dijksma Langer Hassi de Snoo Hassi Wietsma) and non commutative analysis (Ball Bolotnikov Cho Jorgensen).