Seven Papers Translated from the Russian

Abstract

The multiplicative structure of analytic real $J$-expansive matrix-valued functions by I. V. Kovalishina and V. P. Potapov General theorems on the structure and the splitting off of elementary factors of analytic matrix-valued functions by V. P. Potapov An indefinite metric in the Nevanlinna-Pick problem by I. V. Kovalishina and V. P. Potapov Linear fractional transformations of matrices by V. P. Potapov The radii of a Weyl disk in the matrix Nevanlinna-Pick problem by I. V. Kovalishina and V. P. Potapov A theorem on the modulus. I: Main concepts. The modulus by V. P. Potapov A theorem on the modulus. II by V. P. Potapov.