The Complexity of Computable Categoricity
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چکیده
We show that the index set complexity of the computably categorical structures is Π1-complete, demonstrating that computable categoricity has no simple syntactic characterization. As a consequence of our proof, we exhibit, for every computable ordinal α, a computable structure that is computably categorical but not relatively ∆α-categorical.
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تاریخ انتشار 2013