Low upper bounds in the Turing degrees revisited
نویسندگان
چکیده
We give an alternative proof of a result of Kučera and Slaman (2009, Lower upper bounds of ideals, Journal of Symbolic Logic, 74, 517–534) on low bounds of ideals in the 2 Turing degrees. This is a characterization of the ideals in the 0 2 degrees which have a low upper bound. It follows that there is a low upper bound for the ideal of the K-trivial degrees. Our proof is direct, in the sense that it does not use universal classes of PA degrees.
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عنوان ژورنال:
- J. Log. Comput.
دوره 22 شماره
صفحات -
تاریخ انتشار 2012