Cupping Δ20 enumeration degrees to 0e′
Mariya I. Soskova, Guohua Wu · Mathematical Structures in Computer Science · 2009
In this paper we prove that every non-zero Δ20e-degree is cuppable to 0e′ by a 1-generic Δ20e-degree (and is thus low and non-total), and that every non-zero ω-c.e. e-degree is cuppable to 0e′ by an incomplete 3-c.e. e-degree.