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

AbstractWe 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