∑5-completeness of index sets arising from the lattice of recursively enumerable sets Original Research Article

We extend the techniques of Jahn (1996) to show the index set of the major subsets to be ∑5-complete. This was a question left open in Lempp (1987) and its solution involves a level-4 construction. We also show how the measuring of e-states arises naturally out of our iterated-trees approach to breaking up requirements.