Counting $Δ_0$ sets

Instytut Matematyczny Polskiej Akademii Nauk / Institute of Mathematics / Publishing house / Journals and Serials / Fundamenta Mathematicae / All issues

J. Paris, A. Wilkie Fundamenta Mathematicae 127 (1987), 67-76 DOI: 10.4064/fm-127-1-67-76