Countably determined sets and a conjecture of C. W. Henson
The author uses the Robinson methods of nonstandard analysis to give further insight into the relationship between the inverse standard part operator \(st^{-1}\) and topological concepts associated with constructive set theory. He develops a considerable amount of machinery associated with the inverse standard part operator and countably many objects. Along the way, the author shows that \(st^{-1} (X)\) is Souslin-derived from the internal subsets of \(^*X\) if and only if \(X\) is Souslin-derived from the zero sets of \(\beta X\). The author presents other equivalent characterizations for \(st^{-1} (X)\) being Souslin-derived in theorem 3.2. I noticed two * (star) symbols missing.
scientific article; zbMATH DE number 840187
scientific article