Cupping and definability in the local structure of the enumeration degrees
نویسندگان
چکیده
We show that every splitting of 0e in the local structure of the enumeration degrees, Ge, contains at least one low-cuppable member. We apply this new structural property to show that the classes of all K-pairs in Ge, all downwards properly Σ2 enumeration degrees and all upwards properly Σ2 enumeration degrees are first order definable in Ge.
منابع مشابه
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عنوان ژورنال:
- J. Symb. Log.
دوره 77 شماره
صفحات -
تاریخ انتشار 2012