Increasing η ‐representable degrees
A. N. Frolov, M. V. Zubkov · Mathematical logic quarterly · 2009
Abstract In this paper we prove that any Δ30 degree has an increasing η ‐representation. Therefore, there is an increasing η ‐representable set without a strong η ‐representation (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)