Indeterminacy of interpolation problems in the Stieltjes class

The concept of ordered families of interpolation problems in the Stieltjes class is introduced. Ordered families are used for the introduction of the concept of limiting interpolation problem in the same class. The limiting interpolation problem is proved to be soluble. A criterion for the complete indeterminacy of a limiting interpolation problem in the Stieltjes class is obtained. All solutions in the completely indeterminate case are described in terms of linear fractional transformations. General constructions are illustrated by the examples of the Stieltjes moment problem and the Nevanlinna–Pick problem in the Stieltjes class.