### Isomorphism relations on computable structures

Ekaterina B. Fokina, Sy-David Friedman, Valentina Harizanov, Julia F. Knight, Charles McCoy, and Antonio Montalbán
Source: J. Symbolic Logic Volume 77, Issue 1 (2012), 122-132.

#### Abstract

We study the complexity of the isomorphism relation on classes of computable structures. We use the notion of FF-reducibility introduced in [9] to show completeness of the isomorphism relation on many familiar classes in the context of all Σ¹₁ equivalence relations on hyperarithmetical subsets of ω.

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