کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4661745 1633461 2014 25 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Avoiding uniformity in the Δ20 enumeration degrees
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات منطق ریاضی
پیش نمایش صفحه اول مقاله
Avoiding uniformity in the Δ20 enumeration degrees
چکیده انگلیسی
Defining a class of sets to be uniform Δ20 if it is derived from a binary {0,1}-valued function f≤TK, we show that, for any C⊆De induced by such a class, there exists a high Δ20 degree c which is incomparable with every degree b∈C∖{0e,0e′}. We show how this result can be applied to quite general subclasses of the Ershov Hierarchy and we also prove, as a direct corollary, that every nonzero low degree caps with both a high and a nonzero low Δ20 degree.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Annals of Pure and Applied Logic - Volume 165, Issue 9, September 2014, Pages 1355-1379
نویسندگان
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