Andrews U.; Cai M.; Kalimullin I.; Lempp S.; Miller J.; Montalbán A.
(2016)
© 2016, Association for Symbolic Logic.We study Turing degrees a for which there is a countable structure A whose degree spectrum is the collection {x: x ≰ a}. In particular, for degrees a from the interval [0ʹ, 0ʺ ], such ...