Intrinsically Hyperarithmetical Sets
Ivan N. Soskov · Mathematical logic quarterly · 1996
Abstract The main result proved in the paper is that on every recursive structure the intrinsically hyperarithmetical sets coincide with the relatively intrinsically hyperarithmetical sets. As a side effect of the proof an effective version of the Kueker's theorem on definability by means of infinitary formulas is obtained. Mathematics Subject Classification: 03D70, 03D75.