On Schur–Nevanlinna–Pick Indefinite Interpolation Problem
The Schur–Nevanlinna–Pick interpolation problem is considered in the class of generalized Schur functions and reduced to the problem of the extension of a certain isometric operator V that acts in the Pontryagin space. The description of the solutions of this problem is based on the theory of the resolvent matrix developed by Krein.
English version (Springer): Ukrainian Mathematical Journal 55 (2003), no. 10, pp 1567-1587.
Citation Example: Derkach V. A. On Schur–Nevanlinna–Pick Indefinite Interpolation Problem // Ukr. Mat. Zh. - 2003. - 55, № 10. - pp. 1299-1315.