Integral representations of a pair of nonnegative operators and interpolation problems in the Stieltjes class
Yu. M. Dyukarev · Birkhäuser Basel eBooks · 1997
An abstract moment problem (which includes the Stieltjes moment problem and the Nevanlinna-Pick problem as typical representatives) is formulated as an integral representation problem. Potapov’s method is used to show that this problem is solvable if and only if two associated Pick operators are nonnegative, or equivalently if and only if a pair of fundamental matrix inequalities are satisfied. The general solution is described in terms of a linear fractional transformation in the nonsingular case.