Pseudo-jump inversion and SJT-hard sets
Rodney G. Downey, Noam Greenberg · arXiv (Cornell University) · 2011
There are noncomputable c.e.\ sets, computable from every SJT-hard c.e.\ set. This yields a natural pseudo-jump operator, increasing on all sets, which cannot be inverted back to a minimal pair or even avoiding an upper cone.