Categoricity in hyperarithmetical degrees
نویسندگان
چکیده
منابع مشابه
Degrees That Are Not Degrees of Categoricity
A computable structure A is x-computably categorical for some Turing degree x, if for every computable structure B ∼= A there is an isomorphism f : B → A with f ≤T x. A degree x is a degree of categoricity if there is a computable structure A such that A is x-computably categorical, and for all y, if A is y-computably categorical then x ≤T y. We construct a Σ2 set whose degree is not a degree o...
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ژورنال
عنوان ژورنال: Annals of Pure and Applied Logic
سال: 1987
ISSN: 0168-0072
DOI: 10.1016/0168-0072(87)90038-8