Low level nondefinability results: Domination and recursive enumeration
نویسندگان
چکیده
We study low level nondefinability in the Turing degrees. We prove a variety of results, including for example, that being array nonrecursive is not definable by a Σ1 or Π1 formula in the language (≤, REA) where REA stands for the “r.e. in and above” predicate. In contrast, this property is definable by a Π2 formula in this language. We also show that the Σ1-theory of (D,≤, REA) is decidable.
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عنوان ژورنال:
- J. Symb. Log.
دوره 78 شماره
صفحات -
تاریخ انتشار 2013