Complexity and classification of countable models

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Borel classification questions

Let T be a completion of PA. It is not hard to see that the isomorphism problem for finitely generated models of T, fgT, is Borel.

Coskey and Kossak proved that fgT, is essentially countable and E0BfgT i.e. fgT is not smooth. Is fgT hyperfinite? In other words, is fgT Borel reducible to E0?


Reference: Coskey, Samuel, Kossak, Roman The complexity of classification problems for models of arithmetic, Bull. Symbolic Logic 16 (2010), no. 3, 345–358