Classes bounded by incomplete sets
By the authors' definition, a class \textbf{K} of computably enumerable (c.e.) degrees is bounded if there exists an incomplete c.e. set \(A\) such that every set in \textbf{K} is m-reducible to \(A\). An example of a bounded class is the class of effectively simple sets. An interesting property is proved: the class of c.e. sets Turing reducible to an incomplete c.e. set \(A\) is bounded iff \(A\) is \(\text{low}_2\).
scientific article; zbMATH DE number 1758492
scientific article