Abstract
We show that Sacks' and Shoenfield's analogs of jump inversion fail for both tt- and wtt-reducibilities in a strong way. In particular we show that there is a Δ02 set B >tt ∅' such that there is no c.e. set A with A' ≡wtt B. We also show that there is a Σ02 set C >tt ∅' such that there is no Δ02 set D with D' ≡wtt C.
Citation
Barbara F. Csima. Rod Downey. Keng Meng Ng. "Limits on jump inversion for strong reducibilities." J. Symbolic Logic 76 (4) 1287 - 1296, December 2011. https://doi.org/10.2178/jsl/1318338849
Information
