The -Enumeration Degrees
Ivan N. Soskov · Journal of Logic and Computation · 2007
In the present article we initiate the study of the partial ordering of the ω-enumeration degrees. This ordering is a semi-lattice which extends the semi-lattice of the enumeration degrees. The main results include a jump inversion theorem, a density theorem for the ω-enumeration degrees below the first jump of the least degree and the lack of minimal ω-enumeration degrees.